Unit Four
Define antigen-present cells (APCs) and explain the functions of APCs.
In general, APCs engulf a foreign antigen (pathogen) in tissues, process it and present the antigen to T cells in lymph nodes or lymphoid tissues.
Incidence
Indicates how common a disease is during a time period
Which of the following would you use to detect antibodies against HIV in a patient?
Indirect ELISA
Nosocomial infections
Infections acquired in a hospital, nursing home and health care facilities. A localized or systemic condition results from adverse reactions to the presence of infectious agents or its toxin. Was not present or incubating at the time of admission Compromised host: a host whose resistance to infection is impaired Control of nosocomial infections: hand washing is the most important means.
Classic Pathway
Initiated when antibodies bind to antigens.
Prostaglandins
Intensify the effects of histamine and kinins. In addition, prostaglandins help phagocytes move through capillary walls. Prostaglandins are associated with pain related to inflammation and pain killers, such as aspirin, work by inhibiting the production of prostaglandins.
Adhesins
Interaction/binding between the adhesins (surface molecules) on pathogens with the surface receptors on the host cells.
Incubation period
Interval betweeen initial infection and first appearance of signs or symptoms
Why is vasodilation important to tissue repair?
It allows for an increased delivery of oxygen, nutrients, and phagocytes to the site of damage.
Infection Phase 2
# of CD4+ T cells decline; HIV replication continues; a few cells release HIV but much latent infection and provirus; symptoms included persistent yeast infection; fever diarrhea; oral leukoplakia; shingles
Normal flora
(Normal microbiota) The microorganisms reside permanently in or on the body, but do not cause disease under normal conditions.
Epitope
(antigenic determinant) A specific region on the surface of an antigen against which antibodies are formed. Antibodies recognize and interact with.
Type I Reactions - Anaphylactic Reactions
- Binding of antigen to the IgE on mast cells or basophils triggers degranulation and release of mediators such as histamine - Immediate hypersensitivity; within 30 minutes - Localized anaphylaxis - allergies to pollen, hay fever, asthma, foods; often resulted from inhaled or ingested antigens. - Systemic anaphylaxis - called anaphylactic shock, the released mediators cause enlargement of blood vessels and a sudden extreme drop of blood pressure (shock), usually from drug injections or insect stings.
What is a plasma cell?
A cell that produces antibodies.
What results in comparatively long-lasting immunity?
A person survives an infectious disease
Immunoglobulin (Ig)
A protein (antibody) formed in response to an antigen and can react with that antigen.
Antibody
A protein produced by the body in response to an antigen, and capable of combining specifically with that antigen.
Symbiosis
A relationship between two organism where one organism is dependent on the other
Symbiosis
A relationship between two organisms in which at least one organism is dependent on the other, such as in the normal microbiota and the host.
Microbial antagonism
A relationship that allows the normal flora to protect the host from the growth of harmful microorganisms
Inflammation
A second line of defense. A local defensive response triggered by damage to the body's tissues resulting from microbial infection, physical or chemical agents.
Syndrome
A specific group of symptoms or signs accompany a particular disease.
Botulinum toxin
A-B toxin by Clostridium botulinum. A neurotoxin that interferes nerve impulse transmission. Leads to flaccid paralysis.
Tetanus toxin
A-B toxin by Clostridium tetani, also called tetanospasmin. A neurotoxin that blocks the relaxation pathway and results in uncontrollable muscle contractions.
Diphtheria toxin
A-B toxin by Corynebacterium diphtheria. Diphtheria toxin inhibits protein synthesis.
Which pair of molecules do NOT directly interact with one another? A. BCR and TCR B. BCR and epitope C. CD4 and MHC-II D. CD8 and MHC-I
A. BCR and TCR Both of these molecules interact with epitopes. BCRs interact with epitopes on the whole pathogen. TRCs interact with processed epitopes when presented on MHC-II.
Explain how pathogens evade phagocytosis
A. Block adherence by producing capsules or M protein Examples: Streptococcus pneumoniae, Streptococcus pyogenes B. Kill phagocyte by producing leukocidins or streptolysins Examples: Staphylococcus, Streptococcus C. Secrete pore-forming toxins that lyse phagocyte membrane Example: Trypanosome cruzi D. Forms biofilms, which are much more resistant to phagocytosis Example: Pseudomonas aeruginosa
Which of the following features of Salmonella prevent it from being phagocytosed? A. Flagella B. Fimbriae C. Invasins
A. Flagella
Consider the structure of a plasma membrane. Select the mechanisms through which a toxin is likely to disrupt the plasma membrane of a host cell. Select all that apply. A. insertion of a protein channel in the host cell plasma membrane B. disruption of phospholipid bilayer C. binding of the toxin to the lipopolysaccharide layer D. binding of the toxin to the peptidoglycan layer E. blocking synthesis of transport proteins
A. insertion of a protein channel in the host cell plasma membrane B. disruption of phospholipid bilayer
Primary infection
Acute infection that causes the initial illness
To test a patient's serum for evidence of a salmonella infection, you are looking for antibodies. You mix the serum sample with bacteria. What would a positive test show?
Agglutination
Herd immunity
Aka community immunity. When the majority of a population have immunity against an infectious disease, the chance of the non-immunized individuals to contract the disease is little.
Pandemic disease
An epidemic disease that occurs worldwide.
Pandemic
An epidemic that occurs worldwide
Which of the following best describes vaccination?
An individual is exposed to a killed pathogen, an inactivated pathogen, or a component of a pathogen. The individual is protected from subsequent exposures to the pathogen because the adaptive immune system is stimulated to produce memory B cells and memory T cells, which protect from subsequent exposures.
How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic?
Antibiotics can be used in aerosols, thereby entering the environment.
Location of IgD
B cell surface, blood, lymph
Which of the following phagocytic processes occurs last in the sequence? A. Chemotaxis of the phagocyte to the site of infection B. Exocytosis C. Adherence D. Formation of the phagolysosome
B. Exocytosis
Capsules
Bacteria secrete glycocalyx to its cell surface that forms capsules Resist the phagocytosis of host Increases the virulence
Autoimmune Disease
Because of a loss of self-tolerance, the immune system reacts to self-antigens and causes damage to one's own organs.
Mutualism
Both organisms benefit. E.g. e. coli in large intestine.
Mutualism
Both organisms benefit. For example, E. coli in the large intestine.
Location of IgE
Bound to mast and basophil cells through their Fc (stem) regions, throughout body, blood
Cytotoxic Autoimmune Reactions
By antibody reactions to cell-surface antigens Graves' disease Myasthenia
Based on the animation, which of the following is cleaved by C1?
C2 and C4
Based on the animation, which of the following is responsible for cleaving C3?
C2aC4b
Based on the animation, which of the complement proteins can directly bind to the surface of a bacterial cell?
C3b
Which event happens first during cytotoxic T-cell activation?
CD8 binds to MHC molecules of infected cells
This viscous outer covering found in certain microorganisms helps pathogens evade the host 19s defenses by impairing phagocytosis.
Capsules
How can capsules enable bacteria to evade the immune system?
Capsules block the complement biding sites on the surface of the pathogen.
Human reservoirs
Carriers
Etiology
Cause of disease
Secondary infection
Caused by an opportunistic pathogen after the primary infection has weakened the body's defenses
Secondary infection
Caused by an opportunistic pathogen after the primary infection has weakened the body's defenses.
Secondary infection
Caused by opportunistic pathogen after the primary infection has weakened the body's defenses
immunological response that kills infected host cells
Cellular immunity
CDC
Central source of epidemiological info in the U.S. 1) morbidity and mortality weekly report 2) notifiable infectious diseases (which diseases must be reported by physicians)
Symptoms
Change in body function, not apparent to observer
Phagocyte migration and phagocytosis
Chemotactic factors, including complements, leukotrienes, microbial components, and toxins, attract phagocytes to the site of infection. When the phagocytes (monocytes and neutrophils) arrive at the site of infection, the stick to the lining (endothelium) of blood vessels. This process is called margination. Then, the phagocytes squeeze between endothelial cells (this ameboid-like movement is called diapedesis) to reach the site of infection. Neutrophils often arrive first, monocytes follow. Once the monocytes leave the blood into tissue, they change to be free macrophages (wandering macrophages) Neutrophils are involved in the early stages of infection. Macrophages are larger and more phagocytic than neutrophils. Macrophages are usually involved in the later stage of the infection, Both neutrophils and macrophages destroy microbes by phagocytosis; they themselves eventually die and become part of the pus. Note: Fixed macrophages reside in certain tissues and organs of the body, such as Kupffer's cells in the liver, alveolar macrophages in the lungs, and microglial cells in the nervous system. Wandering macrophages are motile and gather at the site of infection or inflammation.
Steps in Phagocytosis
Chemotaxis: The chemical attraction of phagocytes to microorganisms. Adherence: the attachment of the phagocytes (via receptors, such as Toll-like receptors) to the microorganism (through pathogen-associated molecular patterns, PAMPs), or other materials. Microbes are more readily phagocytized when coated with certain antimicrobial proteins called opsonins, such as complements or antibodies. The coating process is called opsonization. Ingestion: The plasma membrane of the phagocyte engulfs the microbe through pseudopods; enclose the microbe in phagosome, which is acidic. Digestion: Phagosome fuses with lysosome to form a phagolysosome, in which the contents are digested.
Which of the following would you likely see on the surface of a human dendritic cell following phagocytosis of a bacterium?
Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
Open Hint for Question 7 in a new window Which of these organisms does NOT produce an enterotoxin? Staphylococcus aureus Shigella spp. Clostridium botulinum Vibrio cholerae
Clostridium botulinum
Endemic disease
Constantly present in a population. E.g. Common cold
Normal microbiota
Contributes in preventing the overgrowth of pathogens.
Differential White Blood Cell Count
Count the percentage of leukocytes (the percentage of each white cell in the total WBC); serves as an indicator of disease.
Which microorganism requires the low pH inside a phagolysosome in order to reproduce?
Coxiella burnetii
What type of molecule activates cytotoxic T lymphocytes?
Cytokines released from T helper cells
Which cells directly attack abnormal cells in the body?
Cytotoxic T cells
Which of the following statements concerning cellular immunity is FALSE? A. The thymus is necessary for development of cells involved in cellular immunity. B. The lymphocytes involved with cellular immunity are found primarily in lymphoid organs and blood. C. T cells respond to antigens when the antigens bind to receptors on their surface. D. Cellular immunity involves cells that recognize antigens and make specific antibodies against them.
D. Cellular immunity involves cells that recognize antigens and make specific antibodies against them.
Which of the following enzymes breaks down the "glue" that holds cells together? A. Collagenase B. Streptokinase C. Fibrinolysin D. Hyaluronidase
D. Hyaluronidase
If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers? A. monocytes B. basophils C. lymphocytes D. eosinophils
D. eosinophils
DNA Vaccines
Deliver DNA into skin cell nuclei with gene gun. Protein antigens encoded in the DNA are produced. Stimulate both humoral and cellular immunity.
Koch's postulates purpose
Demonstrate a specific pathogenic microorganism is the cause of a specific disease. By Robert Koch in 1800s.
Phagocytes that engulf anything foreign. Eventually display etitope to helper T cells using MHC I or II
Dendritic cells
Acute disease
Develops rapidly but does not last
Chronic disease
Develops slowly and may last or recur for a long time
Structure of IgA
Dimer (with secretory component)
This occurs as a result of nutrient depletion, accumulation of waste products, pathogen entry and exit, and ruptured host cells.
Direct Damage
Pathogen
Disease causing microorganism
Subclinical (inapparent) infection
Does not cause noticeable illness
What makes agglutination by antibodies possible?
Each antibody has at least two antigen-binding sites.
To perform a direct ELISA test for rotavirus, you would mix the following ingredients. Which do you add last?
Enzyme substrate
Florence Nightingale
Epidemic typhus in England (1858)
Do erythrocytes play a role in cell-mediated immunity?
Erythrocytes do NOT have a role in cell-mediated immunity.
Antibodies directly interact with which innate defenses? A. The complement system B. Phagocytosis, inflammation, and the complement system C. Inflammation D. First-line defenses E. Phagocytosis F. Phagocytosis and the complement system
F. Phagocytosis and the complement system
Which type of bacterial enzyme helps spread Streptococcus pyogenes by digesting blood clots?
Fibrinolysin
First Line of Defense
First-line defenses keep pathogens on the outside to neutralize them before infection begins. The skin, mucous membranes and certain antimicrobial substance are the physical factors involved in theses defenses. Chemical factors (pH, lysozyme, sebum) and normal microbiota are also part of the first line of defense.
What does the plasma membrane of a phagocyte attach to on a microorganism?
Glycoproteins
Xenograft
Grafts from animals
Which molecule triggers apoptosis?
Granzyme
latent virions
HIV produced by a host cell but not released from the cell; remain as latent virions in vacuoles tihint the cell.
Most important means of control of nosocomial infections
Hand washing
Tears, saliva, urine, mucus and vaginal secretions
Help flush microbes away and prevent colonization of microbes.
What is the role of helper T cells in the adaptive immune response?
Helper T cells activate B cells and cytotoxic T lymphocytes to kill infected host cells. Helper T cells activate B cells that are displaying antigen, causing clonal expansion. Helper T cells also activate cytotoxic T cells, which will search for and destroy infected host cells.
Foodborne Transmission
Hepatitis A Parasitic worms
Humoral immunity
Humoral immunity is immunity brought about by protective molecules called antibodies. Antibodies combat foreign molecules that we refer to as antigens. Humoral immunity involves B lymphocytes, more commonly known as B cells, which remove viruses, bacteria and toxins from body tissue fluids and blood by recognizing antigens and making antibodies against them.
Hyaluronidase
Hydrolyzes hyaluronic acid, an extracellular substance outside of host cells, so the connection among cells is distributed. Involved in the tissue blackening and the spread of the infecting pathogen By streptococci and clostridia (gas gangrene)
Which immunoglobulin class, found in blood, lymph, and the intestine, can cross the placenta and help to protect a fetus?
IgG
Morbidity
Illness
An example of descriptive epidemiology is __________.
John Snow's study of the London cholera outbreak from 1848 to 1849
Which type of vaccine is most likely to be contaminated with endotoxin?
Killed whole-cell vaccine
Which kind of vaccine may confer lifelong immunity against a pathogen?
Live attenuated vaccines
This results in a change in microbe characteristics due to the presence of prophage genes that confer new properties.
Lysogenic conversion
Where is the site of Shigella attachment in the host?
M cells
Which cells are involved in a secondary response?
Memory B cells and plasma cells
What are leukocidins?
Molecules that are capable of destroying phagocytes
Emerging Infectious Diseases (EIDs)
New or changing, showing an increase in incidence recently or potentially in the near future. About 75% of EIDs are zoonotic, viral and vector borne.
Signs
Objective changes observable and measurable
Commensalism
One of the organisms benefits and the other is unaffected. For example, Staphylococcus epidermidis on the surface of the skin.
Parasitism
One organism benefits at expense of the other.
Parasitism
One organism benefits at the expense of the other.
Autograft
One's own tissue is grafted to another part of the body.
__________ pathogens are those that do NOT cause disease in their normal habitat but may do so in a different environment.
Opportunistic
Skin
Physical barrier that blocks the entrance of microbes. It is composed of the outer epidermis (made up of stratified squamous epithelium) and the underlying dermis (dense connective tissue). The dryness and shedding of skin, the thickness of stratum corneum, and the abundance of keratin are protective barriers to the microbes. Subcutaneous infection often develops when broken.
produce and secrete antibodies
Plasma cells
What is the role of plasma cells in humoral immunity?
Plasma cells produce antibodies.
Cytokines
Produced by activated macrophages.
Ignas Semmelweis
Puerperal sepsis in Vienna (1846 - 1848)
Signs and symptoms of inflammation
Redness, pain, heat and swelling, and sometimes loss of function.
Prodromal period
Short period following the incubation period in some diseases. Not all diseases have it. Early, mild symptoms of disease such as aches and malaise.
Which of the following microorganisms use M protein to avoid destruction of a phagocyte?
Streptococcus pyogenes
Can T cells function as antigen-presenting cells?
T cells CANNOT function as an antigen-presenting cell.
lymphocytes that activate B cells and CTLs
Th cells
Where are the complement proteins found in the body?
The blood serum
How does a capsule help certain bacteria evade detection by the immune system?
The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.
Which organelle assists directly with the presentation of MHC-I antigens?
The endoplasmic reticulum
Prodromal period
The first appearance of signs or symptoms
Artificially Acquired Passive Immunity
The injection of antibodies into the body. Immediate yet short-lived protections, last only a few weeks.
Incubation period
The interval between the initial infection and the first appearance of signs or symptoms
Transient microbiota
The microorganisms that are present in or on the body for a period of time and then disappear.
Period of illness
The most severe stage
Colonization
The presence and growth of microorganisms without signs or symptoms.
How is the secondary response different from the primary response in terms of antibody concentration in the blood?
The secondary response is faster and produces more antibodies than the primary response.
Period of decline
The signs and symptoms subside
Naturally Acquired Passive Immunity
The transfer of antibodies from a mother to her infant through placenta or breast milk; may last for weeks or months.
Pathogenesis
The way a disease develops
Pathogenesis
The way a disease develops.
Consider a helminthic infection in which an individual is colonized by a parasitic worm. The worm is too big to be engulfed by a phagocytic cell. How does the immune system respond?
The worm gets coated with antibodies, which activate other cells in the immune system to secrete chemicals that kill it.
How is Streptococcus pneumoniae able to avoid destruction by a phagocyte?
Their capsules make them "slippery" to phagocytes.
Why are invasive procedures likely to increase the risk of nosocomial infections?
These procedures allow microbes from the skin to enter the bloodstream of the patient.
What is the hallmark of a conjugated vaccine?
These vaccines contain weakly antigenic elements plus a more potent antigenic protein.
Tissue repair
Tissue repair replaces the dead or damaged cells. Tissues with stem cells can be restored. Tissues where cells do not replicate cannot be repaired, such as cardiac muscles and brain.
Period of convalescence
Tissues are repaired; patient regains strength and recovers
Period of Convalescence
Tissues repaired. Patients regains strength and recovers. A patient can be infectious during every stage; infections can be spread even during incubation and convalescence.
Vasodilation and increased permeability
Vasodilation and increased permeability of blood vessels caused by chemicals released by damaged cells. Vasodilation is responsible for redness (erythema) and heat. Increased permeability is responsible for the edema (accumulation of fluid). Vasodilation and increased permeability help deliver clotting factors to the injured or infected area and wall off the injurious microbes or agents. Pus
provirus
Viral DNA is integrated into cellular DNA as a provirus that can later be activated to produce infective viruses. This phase is a latent infection.
Lectin Pathway
When macrophages ingest bacteria, viruses and other foreign matter by phagocytosis, they release cytokines that stimulate the liver to produce lectins, proteins that bind to carbohydrates.
When would endotoxins be released from a bacterial cell?
When the cell dies
Herd immunity
When the majority of a population have immunity against an infectious disease, the change of the non-immunized individuals to contract the disease is little; "community immunity."
Activation of the complement system
With the arms (antigen-binding sites) bound to the antigens, antibodies bind to the complement molecules via the stem region (Fc), activate a cascade of reactions by the complement system.
Animal reservoirs
Zoonoses
retrovirus
composed not of DNA but RNA; has reverse transcriptase to produce DNA from RNA template
chemokines
coreceptor required for attachment of HIV spike to CD4
Kill(s) infected host cells
cytotoxic T cells
An exotoxin that has the ability to kill or damage host cells is referred to as a(n)
cytotoxin.
Pus is comprised of
dead phagocytes.
Contact transmission
direct contact transmission, indirect contact transmission and droplet transmission
Some organisms are capable of orchestrating alterations that are collectively termed antigenic variation. This allows an organism to
evade the host's immune system
Koch's postulates
experimental requirements for identifying the agent of an infectious disease.
The influenza vaccine is an example of a(n)
inactivated killed vaccine.
Plasma
involved in blood clotting, inflammation, and transport iron.
pathogenicity of HIV
progresses as it destroys the CD4+ T cells essential for the body's defenses against infectious disease and cancer. AIDS is the final stage
The occurrence of streptococcal bronchopneumonia in an individual recovering from influenza is an example of a __________.
secondary infection
Reservoir of infection
sites, living or nonliving, where pathogens are maintained as a continual source of infection
cell-cell fusion
the virus moves from an infected cell to an adjacent uninfected cell, thereby evading the immune system
Germ theory of disease
this theory states that microorganisms cause infectious diseases.
A vaccine consisting of an inactivated diphtheria toxin is called a
toxoid
Epidemiology is defined as the study of
where and when a disease occurs, and how it is transmitted.
What is the correct sequence of events for activation of a B cell by a T-dependent antigen?
(1) Immunoglobulin receptors on the B cell recognize and bind the antigen. (2) An antigen fragment in complex with MHC class 2 is displayed on the B cell's surface. (3) The MHC-antigen complex binds a receptor on a TH cell. (4) The TH cell secretes cytokines that activate the B cell.
Normal microbiota
(Normal flora) The microorganisms reside permanently in or on the body, but do not cause disease under normal conditions.
Natural killer (NK) cell
- Agranulocyte (lymphocyte) - Kills cancer cells and virus-infected cells
Plasma cell, B cell
- Agranulocyte (lymphocyte) - Recognizes antigens and produces antibodies
T cells (T helper cell, cytotoxic T lymphocyte, T regulatory cell)
- Agranulocyte (lymphocyte) - T helper cells secrete cytokines. They are CD4+ cells that bind MHC class II molecules on antigen-presenting cells (APCs). CTLs recognize and kill specific "non-self" cells. They are CD8+ cells that bind to MHC class I molecules. T regulatory cells are CD4+ cells that destroy cells that do not correctly recognize "self" cells.
Dendritic cells
- Agranulocytes - Derived from the same precursor cells of monocytes - Abundant in the epidermis of the skin, mucous membranes, the thymus and lymph nodes. - Function to destroy microbes by phagocytosis (nonspecific) and to initiate adaptive immunity (specific). Dendritic cells sense the signals from innate immunity and trigger T cell activation, sort of bridging innate immunity and adaptive immunity.
Monocytes
- Agranulocytes - Have kidney-shaped nucleus - Mature to macrophages and become actively phagocytic in the tissues - Number increases during chronic infections, such as tuberculosis
Monocyte
- Both innate and adaptive - Agranulocyte - Precursor to macrophages. Some macrophages are fixed in certain organs while others wander tissues, causing inflammation. All perform phagocytosis.
Neutrophil
- Both innate and adaptive - Granulocyte - Phagocytizes bacteria and fungi
Dendritic cell
- Both innate and adaptive - Many surface projections - In skin and respiratory and intestinal mucosa, phagocytizes bacteria and presents antigens to T cells.
Basophils
- Granulocytes - Granules stain blue-purple - Have a U- or S- shaped nucleus - Release histamine, involved in inflammation and allergic responses
Eosinophils
- Granulocytes - Granules stain red or orange - Have a bi-lobed nucleus - Phagocytic; able to leave the blood - Number increases during parasitic worm (helminths) infections - Involved in inflammation and allergic reactions
Neutrophils
- Granulocytes - The most numerous white blood cell - Granules stain pink - Have multi-lobed nucleus - They have phagocytes; able to leave the blood - Number increases during acute infection
Lymphocytes
- Have a spherical nucleus - T lymphocytes: cellular immunity - B lymphocytes: humoral immunity, produce antibodies - Natural killer cells: function in innate immunity. Kill infected host cells and tumor cells. Natural killer cells release perforin, which pokes a hole in the plasma membrane and causes cytolysis, and granzymes, which induce apoptosis.
Type III Reactions - Immune Complex Reactions
- IgG interacts with soluble, circulating antigens. Normally, IgG-antigen complexes are removed by phagocytosis in liver and spleen. If not, inflammatory damage may occur when the IgG-antigen complexes are deposited in organs, tissues, or joints. - In 3 - 8 hours - Glomerulonephritis, an immune complex reaction because of inflammatory damage to the kidney glomeruli.
Type II Reactions - Cytotoxic Reactions
- IgG or IgM interact with cell surface antigen, activate complement to lyse the cell - In 5 - 12 hours - Transfusion reactions; Rh incompatibility (hemolytic disease of the newborn)
Mast Cells
- Innate - Agranulocyte - Antigen-presenting cells. Produce antibacterial peptides.
Eosinophil
- Innate - Granulocyte - Kill parasites with oxidative burst
Basophil
- Innate - Granulocyte - Release histamines that cause inflammation
Function of IgA
- Localized protection on mucosal surfaces - The most abundant in the body. - Secretory IgA is a dimer, serum IgA is a monomer. - Prevents the attachment of pathogens to mucosal surfaces
Type IV Reactions - Delayed Cell-Mediated Reactions
- Mediated by T cells - Take 24 - 48 hours to develop - Poison ivy, transplant rejection, tuberculin hypersensitivity (skin test for tuberculosis), contact dermatitis
Gamma Interferons
- Produced by lymphocytes - Induces neutrophils and macrophages to kill bacteria - Causes macrophages to produce nitric oxide that inhibits ATP production; thus, kill bacteria and tumor cells - Increases the expression of class I and class II molecules and increases antigen presentation
Alpha Interferons and Beta Interferons
- Produced by virus-infected host cells only in very small quantities that diffuse to infected neighboring cells. - Both are host-cell specific but not virus-specific. - They react with plasma or nuclear membrane receptors, inducing the uninfected cells to express antiviral proteins
Nosocomial infection (table 14.4 & 14.5)
-Infection acquired in a hospital, nursing homes, and healthcare facilities. -Localized or systemic condition results from adverse reaction to presence of an infectious agent of toxin. -was not present or incubating at time of admission
Contact transmission
1) Direct contact transmission -physical. E.g. Viral respiratory tract (cold, flu), staphylococcal, hepA, measles, STD 2) Indirect contact transmission -mediated thru a no living object (a fomite) -e.g. Contaminated syringes are fomites of HIV and hepB 3) Droplet transmission -microbes in mucus droplets discharged. Travel LESS than one meter. -e.g. Cold, flu, pneumonia, pertussis (whooping cough)
Prevalence
1) TOTAL number of cases of a disease in a population at specified time period (either point or period) 2) represents proportion of a population with the disease 3) useful in assessing the impact of a disease in a population and a person's probability of having a disease
Period of illness
1) most severe stage 2) apparent signs and symptoms 3) usually when patient goes to physician 4) immune system has not yet fully responded to the pathogens 5) white blood cells may increase or decrease 6) the treatments and the patient's defense end the period of illness, or the patient dies during this period.
Incidence
1) number of NEW cases of a disease in a population during a particular period 2) indicates how common a disease occurs during a time period 3) an indicator of a person's probability of developing the disease during a time period
Koch's postulates 14.1
1) pathogen must be present in every case of disease 2) pathogen must be isolated from diseased host and grown in culture 3) cultured pathogen must cause disease when inoculated in healthy, susceptible host 4) same pathogen must be isolated from inoculated host
Case reporting
1) procedure that requires health care workers to report specified diseases to health officials 2) provides and approximation of the incidence and prevalence of a disease
Prodromal period
1) short period following incubation in some diseases 2) not all diseases have it 3) early, mild symptoms of disease, such as aches or malaise
Period of decline
1) signs and symptoms subside 2) immune response and products of immune response peak in this stage
Sequence of events leading to a fever
1. Phagocytes ingest gram-negative bacteria 2. Endotoxin (the lipopolysaccharides of the cell wall) is released 3. Causing the phagocyte to release IL-1 and TNF-alpha 4. Causing the hypothalamus to release prostaglandins 5. Causing reset of the hypothalamic thermostat at a higher temperature 6. Causing fever: - Constricting blood vessels - Increasing the rate of metabolism - Shivering
List Koch's postulates.
1. The pathogen must be present in every case of the disease 2. The pathogen must be isolated from the diseased host and grown in pure culture 3. The cultured pathogen must cause the disease when inoculated into a healthy, susceptible host 4. The same pathogen must be isolated from the inoculated hose
Place the following steps of phagocytosis in the order that they occur: 1. Endosome fuses with lysozome 2. Dendritic cell engulfs Rhinovirus 3. Epitopes are attached to MHC-II 4. Digestion of the Rhinovirus 5. MHC-II plus the attached epitope move to the outside of the dendritic cell
2,1,4,3,5
Correctly order the steps involved cellular immunity: 1. The Tc recognizes the infected host cell 2. The Tc interacts with epitope presented by MHC-I on the dendritic cell 3. The Tc secretes perforin and granzyme, causing apoptosis 4. The helper T cell activates the Tc cell
2,4,1,3
According to the animation, surgical infections account for what percentage of nosocomial infections?
20%
Type IV (Delayed, Cell-Mediated, or Delayed Hypersensitivity) Time Before Clinical Signs
24 - 48 hours
Type III (Immune Complex) Time Before Clinical Signs
3 - 8 hours
Type II (Cytotoxic) Time Before Clinical Signs
5 - 12 hours
Type I (Anaphylactic) Time Before Clinical Signs
<30 minutes
Structure of an antibody
A basic antibody has two identical heavy chains and two identical light chains, linked by disulfide bridges, form a Y-shaped molecule. Constant regions: The lower parts of the two arms and the stem of the Y; they are the same for all antibodies of the same class. Variable regions: The top portion of the two arms of the Y, which has the antigen-binding sites (formed by the heavy chains and the light chains) that bind to epitopes. The variable regions vary from antibody to antibody. Each Y-shaped molecules has two antigen-binding sites. (Light and heavy refer to the relative molecular weights)
Agglutination
A basic monomer antibody, such as IgG, has two antigen-binding sites. It can bind to two antigens, causes the antigens to clump together, becomes insoluble and precipitate. IgM is a pentamer; is has 10 antigen-binding sites. IgM is a more effective agglutinating molecule than IgG.
Leukopenia
A decrease in the leukocyte count may be caused by salmonellosis, brucellosis, and some viral and rickettsial infections.
Noncommunicable disease
A disease that does not spread from one host to another
Noncommunicable disease
A disease that does not spread from one host to another 1) caused by one's own microbiota (e.g. pneumonias) Or 2) when external microorganisms are introduced into the body (e.g. clostridium tetani)
Noncommunicable disease
A disease that does not spread from one host to another. Caused by one's own microbiota (for example, pneumonias) or when external microorganisms are introduced into the body (for example, Clostridium tetani)
Contagious disease
A disease that easily spreads from one person to another
Contagious disease
A disease that is easily spread from one person to another.
Emerging infectious disease
A disease that is new or changing, showing an increase in incidence
Communicable disease
A disease that spreads from one host to another, directly or indirectly.
Latent disease
A disease that the pathogen remains inactive for a period of time before becoming active
Latent disease
A disease that the pathogen remains inactive for a period of time before becoming active.
Latent disease
A disease where the pathogen remains inactive for a period of time before becoming active
Compromised host
A host whose resistance to infection is impaired
Thymus
A mammalian organ responsible for maturation of the immune system.
Pus
A mixture of dead tissue cells, leukocytes, pathogens and body fluids in a walled-off area.
Fomite
A nonliving object that can spread infection
Case Reporting
A procedure that requires health care workers to report specified diseases to health officials. Provides an approximation of the incidence and prevalence of a disease.
Phagocytosis
A second line of defense. Phagocytosis is the ingestion of a microorganism or other substance by a cell. Phagocytes are cells that perform phagocytosis. All phagocytes are white blood cells or derived from white blood cells.
Microbial antagonism
A situation where microbes inhibit colonization and growth of others by competing for the resources and/or producing bacteriocins
Biofilms
A slimy community of microbes growing on a surface; formed by the masses of microbes and their extracellular products attach to living or nonliving surfaces. Method of adherence Resistant to disinfectants and antibiotics Involved in 65% of all human bacterial infections.
Staphylococcal enterotoxin
A superantigen by Staphylococcus aureus. This toxin causes loss of large amounts of water and electrolytes that results in diarrhea.
Vaccine
A suspension of organisms or fractions of organisms that is used to induce immunity.
Septicemia
A systemic infection arising from the multiplication of pathogens in the blood
Sepsis
A toxic inflammatory condition arising from the spread of microbes
Sepsis
A toxic inflammatory condition arising from the spread of microbes.
T Cells
A type of lymphocyte, which develops from a stem cell processed in the thymus gland, that is responsible for cell-mediated immunity.
B Cells
A type of lymphocyte; differentiates into antibody-secreting plasma cells and memory cells. B cells remove viruses, bacteria and toxins from body tissue fluids and blood by recognizing antigens and making antibodies against them. The recognition of different antigens depends on B cell receptors for antigens that coat the surface of the B cell.
Vibrio enterotoxin
A-B toxin by Vibrio cholera, called cholera toxin. The subunit B binds to epithelial cells; the subunit A causes loss of large amounts of water and electrolytes from cells that results in diarrhea.
Which of the following statements is true? A. Adaptive defenses include both humoral and cellular immunity. B. Innate defenses are enough to keep a person healthly. C. Adaptive defenses include humoral immunity only. D. Memory B cells are typically established when the B cell binds to an antigen.
A. Adaptive defenses include both humoral and cellular immunity.
Which of the following is an example of the symbiotic relationship known as mutualism? A. E. coli within the large intestine B. Corynebacterium on the surface of the eye C. a tapeworm in the gastrointestinal tract of a human D. saprophytic Mycobacterium of the ear
A. E. coli within the large intestine E. coli is a bacterium that lives in the large intestine synthesizing of vitamin K and some B vitamins.
Which of the following statements about innate immunity is true? A. Innate immunity is present at birth. B. It involves the activity of B and T cells. C. The innate immune response does not have a mechanism for detecting invading microorganisms. It is activated only in response to tissue damage or a signal from an infected cell. D. Innate immunity involves specific recognition of microorganisms via a memory response.
A. Innate immunity is present at birth.
A rabbit was found to have floppy ear disease, which causes long-ear infections. Its etiology (cause) is unknown. Unknown Microorganism X from the infected rabbit's right ear is successfully isolated and cultured on laboratory growth media. The ear of a healthy laboratory mouse is then inoculated with isolated microorganism, and after a period of time, no disease is observed. Which of the following statements accurately describe(s) the conclusion(s) that can be drawn from this experiment? Select all that apply. A. Microorganism X might not be linked to floppy ear disease, because the inoculated mouse remained healthy. B. Microorganism X is the etiologic agent for floppy ear disease because it caused infection in the diseased rabbit. C. A laboratory mouse might not be an appropriate, susceptible host; an experiment with a laboratory rabbit may be needed. D. It is not possible to isolate and culture microorganism X in the laboratory, because this microbe is found in nature. E. Healthy laboratory organisms rarely show signs and symptoms of infection and disease. F. Microorganism X modified its cell wall structure while being cultured, and is no longer infectious to rabbits.BCD
A. Microorganism X might not be linked to floppy ear disease, because the inoculated mouse remained healthy. C. A laboratory mouse might not be an appropriate, susceptible host; an experiment with a laboratory rabbit may be needed.
Which of the following statements concerning pathology, infection, and disease is true? A. Pathology refers to the study of structural and functional changes that occur in the body as a result of a disease. B. Microorganisms that make up the normal microbiota of an individual never cause disease. C. The term infection is synonymous with the term disease. D. The majority of microorganisms are pathogenic.
A. Pathology refers to the study of structural and functional changes that occur in the body as a result of a disease.
Examples of adhesins:
A. Streptococcus mutans (dental caries) - glycocalyx B. Escherichia coli (diarrhea) - adhesins on fimbriae C. Shigella (dysentery) - fimbriae D. Neisseria gonorrhoeae (gonorrhea) - adhesins on fimbriae E. Treponema pallidum (syphilis) - attaches via its tapered end
Which of the following statements concerning immunological memory is true? A. The memory response is due to production of long-lived cells that can respond very rapidly upon second exposure. B. The memory response is usually faster but not as strong. C. Antibodies produced in response to a secondary infection are mostly IgM. D. The memory response involves only B cells.
A. The memory response is due to production of long-lived cells that can respond very rapidly upon second exposure.
Koch's postulates established criteria for proving that a specific organism causes a specific disease. Which of the following is NOT one of the criteria given by Koch's postulates? A. The pathogen must be isolated from inoculated animals and must be different from the original organism. B. The same pathogen must be present in every case of the disease. C. The pathogen isolated from a pure culture must cause the disease in a healthy lab animal. D. The pathogen must be isolated from the diseased host and grown in pure culture.
A. The pathogen must be isolated from inoculated animals and must be different from the original organism.
Which statements accurately describe Koch's postulates? Select all that apply. A. The same pathogen must be present in every case of the disease. B. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism. C. The microscopic properties of pathogens isolated from the original (diseased) and inoculated (also diseased) animals should differ significantly. D. The pathogen must be isolated from the diseased host and grown in pure culture. E. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.
A. The same pathogen must be present in every case of the disease. B. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism. D. The pathogen must be isolated from the diseased host and grown in pure culture. E. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.
Which of the following microorganisms actually grows inside the macrophage? A. Tuberculosis bacterium B. Leishmania C. Legionella D. Streptococcus pneumoniae E. Shigella
A. Tuberculosis bacterium
Which of the following strategies might be used to block the activity of an A-B toxin? Select all of the strategies below that might inhibit or block the action of an A-B toxin. A. blocking host cell receptors to which A-B toxins bind B. interfering with lipopolysaccharide synthesis in gram-negative bacteria C. inhibiting cytokine release stimulated by endotoxin D. inhibiting the secretion of proteins from a bacterial cell E. blocking separation of the A and B components of the toxin F. blocking receptor-mediated endocytosis in cells targeted by the A-B toxin G. blocking the binding sites on the B portion of an A-B toxin
A. blocking host cell receptors to which A-B toxins bind D. inhibiting the secretion of proteins from a bacterial cell E. blocking separation of the A and B components of the toxin F. blocking receptor-mediated endocytosis in cells targeted by the A-B toxin G. blocking the binding sites on the B portion of an A-B toxin
The following choices list several types of diseases, along with factors that may contribute to their emergence. Which disease and associated factor do NOT match? A. emergence of avian influenza A (H5N1); use of antibiotics B. spread of cholera to new regions; modern travel C. increased incidence of Lyme disease; D. increases in deer populations E. increased incidence of malaria; global warming
A. emergence of avian influenza A (H5N1); use of antibiotics Emergence of avian influenza A is not associated with the use of antibiotics. Avian influenza is cause by a virus, which cannot be controlled with antibiotics.
In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used? A. to ensure that a sterilized medical device is free of endotoxin B. to detect the presence of the botulinum toxin C. to confirm the diagnosis of gas gangrene D. to check for enterotoxins
A. to ensure that a sterilized medical device is free of endotoxin
Assuming Rh compatibility is present, individuals with which of the following blood types would be able to receive donor blood from any of the four blood types (A, B, AB, and O)?
AB
Infection Phase 3
AIDS; CD4+ cells decline to less than 200 cells per milliliter. yeast on bronchi, tracheo, lungs; cytomegalovirus of eyes, tuberculosis; pheumonia, toxoplasmosis of brain; Kaposi's sarcoma.
Disease
Abnormal state in which body is not preforming it's normal functions
Emerging Infectious Disease
About 75% of EIDs are zoonotic, viral and vector-borne
Clonal Expansion
Activated B cells proliferate into a large clone of cells, which differentiate into plasma cells and memory cells
What statement about T-dependent antigens is true?
Activation of a B cell by a T-dependent antigen requires cytokines secreted by a T helper cell.
Competitive exclusion
Aka microbial antagonism. Involves competition among microbes- once established, normal microbiota can benefit the host by preventing overgrowth of harmful microorganisms.
Normal flora
Aka normal microbiota. Microorganisms that reside permanently in or on body but do not cause disease under normal conditions
Functions of IgE
Allergic reactions; possibly lysis of parasitic worms - Involved in allergic reactions - IgE increases during allergic reactions and parasitic infections
Microbial antagonism
Also called competitive exclusion. By competing for resources and/or producing bacteriocins, the normal microbiota protect the host by preventing the colonization and overgrowth of harmful microorganism (See examples of Candida albicans, Salmonella, Shigella, and Clostridium difficile).
Competitive exclusion
Also called microbial antagonism. By competing for resources and/or producing bacteriocins, the normal microbiota protect the host by preventing the colonization and overgrowth of harmful microorganism (See examples of Candida albicans, Salmonella, Shigella, and Clostridium difficile).
Antigenic Variation
Alter surface antigens so not to be recognized by the antibodies from the host. Multiple copies of the Opa-encoding gene in Neisseria gonorrhoeae result in antigenic changes. Influenza virus (explains the need of an annual flu shot)
Hypersensitivity (allergy)
An abnormal antigenic response results from a prior exposure to a foreign substance called an allergen, an antigen that evokes a hypersensitivity response.
Disease
An abnormal state in which the body is not performing its normal functions.
What is meant by the clonal expansion of a B cell?
An activated B cell divides into cells that give rise to memory B cells and plasma cells. The activated B cell divides until there are many clones. Some differentiate into memory cells, other become plasma cells that produce and secrete antibodies.
Primary infection
An acute infection that causes the initial illness
Primary infection
An acute infection that causes the initial illness.
What is the primary benefit of vaccination?
An immune response will occur quicker upon future exposure to the pathogen.
Incidence
An indicator of a person's probability of developing a disease during a time period
Focal infection
An infection originated from a local infection, later the pathogen or its products spread from the local infection area to other parts of the body
Focal infection
An infection originated from a local infection, later the pathogen or its products spread from the local infection area to the other parts of the body.
Abscess
An isolated site of infection. For example, pimples, boils and postules.
Analytical epidemology
Analyze a particular disease to determine its probable cause, mode of transmission, and possible means of transmission.
Analytical Epidemiology
Analyze a particular disease to determine its probably cause, mode of transmission and possible means of prevention.
Type I (Anaphylactic) Examples
Anaphylactic shock from drug injections and insect venom; common allergic conditions such as hay fever and asthma.
A response that is uniquely directed against pathogenic Bordetella pertussis would involve what component?
Antibodies
Type III (Immune Complex) Characteristics
Antibodies and antigens form complexes that cause damaging inflammation.
Neutralization
Antibodies block the activities of antigens, such as microbes and toxins by binding to them, preventing their attachment to the host cells.
Antibody-Dependent Cell-Mediated Cytotoxicity
Antibodies coat the target cell (a parasitic worm, for example), and then macrophages, eosinophils and that natural killer (NK) cells bind to the stem region (Fc) of antibodies. These cells of immune system the secrete substance to lyse the target cell.
Opsonization
Antibodies stimulate phagocytosis by binding to the antigen, such as the surface of a bacterial cell.
Agglutination Reactions
Antibodies with two or more antigen-binding sites, such as 2 in IgG and 10 in IgM, are able to cross-link antigens causing agglutination (clumping). Agglutination is routinely used in ABO and Rh blood type testing, which is called hemagglutination.
Plasma cells
Antibody-producing cells. In general, short-lived.
Monoclonal Antibody (MAbs)
Antibody-producing plasma cells (normal cells) are fused with myeloma cells (cancerous cells that are able to divide continuously but cannot produce antibody) The resulted hybridomas have the properties of both; they are able to divide continuously as well as to produce antibody. A clone of cells derived from one hybridoma can be isolated and grown in culture indefinitely. The antibody molecules produced by the cells of the same clone are identical; they are called monoclonal antibodies. Monoclonal antibodies are very useful - they are identical; they are highly specific and they can be produced in large quantities.
To perform an indirect ELISA test to identify the strain of influenza in a patient, you would mix the following ingredients. Which do you add first?
Antigen
Type II (Cytotoxic) Characteristics
Antigen caused formation of IgM and IgG antibodies that bind to target cell; when combined with action of complement, destroy target cell.
This process allows pathogens to alter their surface antigens to avoid attack by antibodies produced by the immune system.
Antigenic Variation
Type IV (Delayed, Cell-Mediated, or Delayed Hypersensitivity) Characteristics
Antigens activate TC that kills target cell.
T-Independent Antigen
Antigens that directly stimulate B cells to produce antibodies without the help of T helper cells. Characterized by repeating subunits, such as polysaccharides. Provoke a weaker immune response that the T-dependent antigens fo. No memory cells are generated.
T-Dependent Antigens
Antigens that require the help of T helper cell for antibody production. For instance, proteins and haptens with their carriers.
While on safari in Serengeti National Park, Tanzania, your friend ventures away from camp and is bitten by a black widow spider. Fortunately, you are prepared and administer artificially acquired passive immunity. With what did you inject your friend?
Antivenin
Immunogen
Any substance that causes antibody formation.
Antigen
Any substance that causes antibody formation; also called an immunogen
Type III (Immune Complex) Examples
Arthus reactions, serum sickness
You are about to start a multiyear experiment in a laboratory that works with poliovirus. Although the chance of exposure is low, you are still required to get immunized. What type of immunity now protects you?
Artificially acquired active immunity
Which type of vaccine could possibly cause a person to develop the disease?
Attenuated live vaccine
TH2 cells produce cytokines that activate
B cells
Which domain of the A-B toxin binds to cell surface receptors on the host cell?
B domain
Which of the following is considered a major category of transmission of disease? A. Contact transmission B. Contact, vehicle, and vector transmission C. Vector transmission D. Vehicle transmission
B. Contact, vehicle, and vector transmission
Characteristics of Endotoxin Select the statements that correctly describe endotoxins. A. Endotoxins can be used to vaccinate individuals. B. Endotoxins can cause fever, chills, weakness, and fatigue. C. Endotoxins may cause a life-threatening drop in blood pressure known as endotoxic shock. D. Symptoms caused by endotoxins may actually worsen after treatment of an infection caused by gram-negative bacteria. E. Endotoxins cause a strong immune response and abundant antibody production in the host. F. Drugs that neutralize endotoxins will kill gram-negative bacteria. G. Sterilized items may contain endotoxins and cause a reaction in a patient.
B. Endotoxins can cause fever, chills, weakness, and fatigue. C. Endotoxins may cause a life-threatening drop in blood pressure known as endotoxic shock. D. Symptoms caused by endotoxins may actually worsen after treatment of an infection caused by gram-negative bacteria. G. Sterilized items may contain endotoxins and cause a reaction in a patient.
Why is a release of endotoxin into the bloodstream potentially deadly? A. It causes necrosis of the liver. B. It can lower blood pressure and cause the patient to go into shock. C. Endotoxin can quickly enter the brain from the bloodstream, causing brain damage. D. It results in dehydration of the patient.
B. It can lower blood pressure and cause the patient to go into shock.
Bacillus anthracis can cause infection via three different portals of entry. The ID50 of cutaneous anthrax is 10 to 50 endospores, whereas inhalation anthrax requires 10,000 to 20,000 endospores, and gastrointestinal anthrax requires 250,000 to 1,000,000 endospores. Which statement best describes a conclusion that can be drawn based on this information? A. The portal of exit impacts the infectious dose needed to cause infection at the portal of entry. B. It is significantly easier to be infected with cutaneous anthrax as compared to other forms of anthrax. C. Exposure to a small number of endospores (fewer than 1000) is most likely to result in gastrointestinal anthrax. D. Cutaneous anthrax is rarely observed when cases across the population are monitored E. Equal numbers of cutaneous, inhalation, and gastrointestinal anthrax infections are observed in human hosts.
B. It is significantly easier to be infected with cutaneous anthrax as compared to other forms of anthrax.
An inflammatory response would result from which of the following? A. Vomiting B. Jellyfish sting C. A headache
B. Jellyfish sting
Which of the following statements about adherence is true? A. The host cell receptors for bacterial adhesins are usually proteins. B. Most bacterial adhesins are glycoproteins or lipoproteins. C. Adhesins are always located on the bacterium's cell membrane. D. Most bacteria can adhere to any cell in the host.
B. Most bacterial adhesins are glycoproteins or lipoproteins.
Which statement regarding endotoxins is true? A. The effects of endotoxins vary greatly, depending on the specific bacterium the produces them. B. One consequence of endotoxins is the activation of blood-clotting proteins. C. Endotoxins are part of the outer portion of the cell wall of gram-positive bacteria. D. Endotoxins induce host cells to produce effective antitoxins that help to protect them against the toxin's effects.
B. One consequence of endotoxins is the activation of blood-clotting proteins.
Which of the following is NOT a step used by cytotoxic T cells to kill infected host cells? A. Secretion of perforin B. Recognition of infected host cell using its CD4 glycoprotein C. Recognition of infected host cell using its TCR D. Secretion of granzyme
B. Recognition of infected host cell using its CD4 glycoprotein
Which of the following most accurately describes how a pathogenic bacterium might be affected by antibodies? A. The antibodies may stick to multiple bacteria, causing agglutination. B. The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria. C. The antibodies may block proteins necessary for binding the pathogen to the host. D. The antibodies may coat the surface of the bacteria (opsonization), allowing for it to be tagged for phagocytosis.
B. The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria.
Which is an example of vehicle disease transmission? A. Touching a telephone with cold viruses on its surface B. The presence of Listeria on undercooked chicken served for dinner C. The transmission of MRSA from skin to skin contact D. The bite of a mosquito containing malaria
B. The presence of Listeria on undercooked chicken served for dinner
Which of the following best characterizes clonal selection? A. The production of different antigens by the same B cell B. The production of identical B cells producing the same antibody C. The production of identical B cells producing different antibodies D. The production of identical T cells producing the same antibody
B. The production of identical B cells producing the same antibody
Which of the following statements concerning antigen-presenting cells is true? A. They are a type of T cell. B. They are involved in activating T cells. C. They transport antigens to the liver, where they can be degraded. D. They are found only in lymphoid tissues.
B. They are involved in activating T cells.
Which of the following is a xenotransplantation product? A. transplantation of a kidney from a woman to her older brother B. the replacement of a human's heart valve with a pig's heart valve C. transplantation of tissue from one area on a person's body to another D. transplantation of a kidney from a woman to her twin sister
B. the replacement of a human's heart valve with a pig's heart valve
What type of nosocomial infection is likely to arise from intravenous catheterizations?
Bacteremia
What is the function of the CD8 receptor?
Bind to MHC molecules
Mucous membranes
Block the entrance of microbes. Consist of an epithelial layer and an underlying connective tissue layer. Mucous membranes line the entire gastrointestinal, respiratory and genitourinary tracts.
Septicemia
Blood poisoning, a systemic infection arising from the multiplication of pathogens in the blood. Common example of sepsis
Septicemia
Blood poisoning, a systemic infection arising from the multiplication of pathogens in the blood; a common example of sepsis.
Location of IgM
Blood, lymph, B cell surface (as monomer)
Location of IgG
Blood, lymph, intestine
What is the function of boosters?
Boosters are injections that are given periodically to maintain immunity.
Bone Marrow
Both B and T cells originate from stem cells in adult red bone marrow or in the fetal liver. Some cells pass through the thymus and emerge as mature T cells. Other cells remain in the red bone marrow and become B cells. Both types of cells then migrate to lymphoid tissues, such as the lymph nodes or spleen.
Which of the following is NOT a step that ultimately leads to antibody production? A. Differentiation of plasma cells B. Immature B cells conducting surveillance for foreign epitopes C. Activation of cytotoxic T cells by helper T cells D. Activation of helper T cells by dendritic cells
C. Activation of cytotoxic T cells by helper T cells The activation of cytotoxic T cells leads down the path of cell-mediated immunity.
Which of the following would be considered a fomite? A. A tick B. A fly C. An infected toy D. Contaminated water
C. An infected toy
Which of the following statements concerning phagocytosis is true? A. Adherence always requires opsonization. B. Phagocytes ingest microorganisms by using protein transporters that are specific to the bacteria. C. Bacteria are digested when the phagosome fuses with a lysosome. D. Phagocytes cannot ingest microorganisms unless they are coated with antibodies.
C. Bacteria are digested when the phagosome fuses with a lysosome.
Which of the following are likely to be found on an MHC-I protein? A. Membranes from a neighboring dead host cell B. Bacterial DNA C. Damaged mitochondrial fragment D. Bacterial cell wall fragment E. Bacterial flagella
C. Damaged mitochondrial fragment
Which of the following would be the first sign of an infection that resulted in the release of endotoxin? A. Weakness B. Nausea C. Fever D. Pain
C. Fever
What is produced by the process of clonal expansion? A. Plasma cells, T cells, and memory B cells B. Memory B cells C. Plasma cells and memory B cells D. Plasma cells
C. Plasma cells and memory B cells
Which of the following defense systems would be involved in eliminating virally-infected cells? A. Humoral immunity B. Phagocytosis C. T lymphocytes D. Complement system
C. T lymphocytes
Which of the following toxins and descriptions do NOT match? A. tetanus toxin: an A-B neurotoxin that causes uncontrollable muscle contractions B. streptococcal erythrogenic toxin: a superantigen that damages capillaries and results in a characteristic rash C. Vibrio enterotoxin: a superantigen that destroys epithelial cells D. hemolysins: membrane-disrupting toxins that destroy erythrocytes
C. Vibrio enterotoxin: a superantigen that destroys epithelial cells
These structures contain substances that contribute to a pathogen 19s virulence; for example, M protein mediates microbial attachment to epithelial cells.`
Cell wall components
Symptom
Changes in body function, not apparent to an observer.
Waterborne Transmission
Cholera
John Snow
Cholera in London (1848 - 1849)
What would a virally infected skin epithelial cell have on its cell surface?
Class I MHC with skin cell antigens
A person who has AIDS contracts rare and often life-threatening infections because their helper T cell count is so low. Which of the following components of the immune response still respond to antigen despite the low helper T cell count?
Clonal selection of B cells B cells can still bind to antigen, which is the process of clonal selection. However, without a helper T cell, clonal expansion and antibody production will not occur.
Collagenase
Collagenase produced by Clostridium breaks down collagen, thus, facilitates the spread of gas gangrene.
Descriptive Epidemiology
Collect all data and describe the occurrence of the disease.
Descriptive epidemiology
Collect all data that describe the occurrence of the disease
Endemic disease
Constantly present in a population; common cold.
Cytolysis:
Cytolysis of microbial cells involves the membrane attack complex (MAC), which is formed by C5b through C8 and the multiple fragments of C9. The MAC creates a hole on a pathogen's cell membrane and makes transmembrane channels, allowing for flow of extracellular fluid into the pathogen. The fluid inflow bursts the microbial cell. Plasma membranes of the host cell contain proteins that protect against lysis by preventing the MAC proteins from attaching to their surfaces. Also, the MAC forms the basis for the complement fixation test used to diagnose some diseases. Gram-negative bacteria are more susceptible to cytolysis because they have only one or very few layers of peptidoglycan to protect the plasma membrane from the effects of complement. Gram-positive bacteria have many layers of peptidoglycan, which limit complement's access to the plasma membrane and thus interfere with cytolysis.
These describe the visible effects of viral infections that results in host cell damage.
Cytopathic effects
Which type of cell directly attacks infected cells?
Cytotoxic T-cells
HIV directly infects T-cells. Why is this problematic for cell-mediated immunity?
Cytotoxic T-cells begin to attack the virally infected T-cells, reducing the number of T-cells in the body.
Which of the following would be considered a vector? A. Saliva that is transmitted between individuals during kissing B. Water containing bacteria from fecal matter C. Water droplets that come from a sneeze from an infected individual D. A fly carrying disease from fecal matter to food
D. A fly carrying disease from fecal matter to food
Which of the following is NOT a cytopathic effect (CPE) of viruses? A. the formation of a syncytium B. formation of inclusion bodies C. chromosomal changes in the host cell D. All of the listed choices are possible cytopathic effects of viruses.
D. All of the listed choices are possible cytopathic effects of viruses.
Which of the following would be an example of an infection initiated via the parenteral route? A. An individual contracts a gastrointestinal infection by consuming contaminated water. B. An individual contracts gonorrhea as a result of unprotected sex. C. An individual contracts a hookworm infection as a result of walking around outside barefoot. D. An individual contracts hepatitis B from an accidental stick with a contaminated needle.
D. An individual contracts hepatitis B from an accidental stick with a contaminated needle.
Which of the following statements about lysogenic conversion is true? A. Endotoxin production by bacteria is frequently the result of a lysogenic infection. B. Lysogenic bacteria are always less virulent than non-lysogenic bacteria because the viral infection weakens them. C. Lysogenic conversion is a result of the transfer of plasmids from one bacterium to another. D. Exotoxin production by bacteria is frequently the result of a lysogenic infection.
D. Exotoxin production by bacteria is frequently the result of a lysogenic infection.
Which of the following statements about beta interferons is true? A. It is produced only in response to infection with the hepatitis B virus. B. It is a protein that specifically degrades viral RNA. C. It induces neutrophils and macrophages to kill bacteria. D. It acts as a signal that induces uninfected cells to produce antiviral proteins.
D. It acts as a signal that induces uninfected cells to produce antiviral proteins.
Which statement regarding the lymphatic system is true? A. The pancreas contains lymphocytes and macrophages that monitor the blood for microbes. B. The thymus serves as the site for activation of B cells. C. Lymph nodes are sites of activation of neutrophils, which destroy microbes. D. Lymphatic capillaries possess one-way valves. These valves permit the uptake of fluid from the body but do not allow the fluid to flow back out of the capillaries into the intracellular spaces.
D. Lymphatic capillaries possess one-way valves. These valves permit the uptake of fluid from the body but do not allow the fluid to flow back out of the capillaries into the intracellular spaces.
Which of the cells listed below can present antigens on Class II MHC proteins? A. Virus infected epithelial cells B. Healthy epithelial cells C. Tumor cells D. Macrophages
D. Macrophages
In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true? A. More organisms of Staphylococcal bacteria must be ingested to cause infection, as compared to Shigella bacteria. B. The parenteral route is the preferred portal entry for Shigella bacteria. C. Staphylococcal enterotoxin is the more lethal of the two toxins. D. Shiga toxin is more lethal than staphylococcal enterotoxin.
D. Shiga toxin is more lethal than staphylococcal enterotoxin.
Which of the following virulence factors would be found in Staphylococcus aureus? A. Collagenase B. Hyaluronidase C. Streptokinase D. Staphylokinase
D. Staphylokinase
Which of the following statements about the development of infectious diseases is correct? A. During the incubation period, the infected individual exhibits obvious signs of sickness. B. The period of decline is the time when the infected individual's health rapidly deteriorates. C. The prodromal period is characterized by very severe symptoms. D. The period of convalescence is the time during which the person regains health and fully recovers (back to the pre-disease state).
D. The period of convalescence is the time during which the person regains health and fully recovers (back to the pre-disease state).
Which of the following is NOT an advantage of using live attenuated vaccines? A. They are usually highly effective. B. They often do not require boosters. C. They often produce a more complete type of immunity that includes both humoral and cell-mediated components. D. They are usually safer than other types of vaccines.
D. They are usually safer than other types of vaccines.
Which of the following are best described as short chains of amino acids that are very stable and can have a variety of different antimicrobial activities, such as forming pores in bacterial plasma membranes and inhibiting cell wall synthesis? A. antiviral proteins B. siderophores C. mannose-binding lectin D. antimicrobial peptides
D. antimicrobial peptides
Which of the following is classified as a latent disease? A. influenza B. infectious mononucleosis C. tuberculosis D. shingles
D. shingles
According to the animation, on what day does IgM first appear?
Day five
According to the animation, on which day does the production of IgG occur in the secondary response?
Day five
Mortality
Death
Communicable disease
Disease that spreads from one host to another, directly or indirectly
Pathogen
Disease-causing microorganisms.
Notifiable Infectious Disease
Diseases for which physicians are required by law to report cases to the U.S. Public Health Service.
Membrane-Disrupting Toxins
Disrupt cell membrane and cause lysis of host cells by: (1) Forming protein channels: Staphylococcus aureus Leukocidins - membrane-disrupting toxins that kill phagocytic leukocytes Hemolysins - membrane-disrupting toxins that kill erythrocytes (2) Disrupts the phospholipid of cell membrane; for example, Clostridium perfringens (1
Opportunistic pathogens
Do not cause disease in normal habitat in a healthy person. May cause disease if: 1) gains access to other sites of the body 2) host is weakened 3) is present in large numbers
When does MHC-II loading occur?
During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens
Which of the following can release histamines? A. Wood from a splinter B. Invading bacterial cells C. Cells from damaged tissues D. The complement system E. Cells from damaged tissues and the complement pathway
E. Cells from damaged tissues and the complement pathway
How can a sufficient humoral immune response occur if a plasma cell only lives for a few days
Each plasma cell can produce up to 2000 antibodies every second.
You conduct a Limulus amebocyte lysate (LAL) assay on a sample of fluid that should be sterile. The result is positive. What does this indicate?
Endotoxin is present.
Functions of IgG
Enhances phagocytosis, neutralizes toxins and viruses; protects fetus and newborn - 80%, the most abundant in serum - Can cross the placenta and protect the fetus and newborn
These proteins contribute to a pathogen 19s virulence by, for example, forming and breaking down fibrin clots, breaking down connective proteins, and countering certain types of antibodies.
Enzymes
Functions of IgM
Especially effective against microorganisms and agglutinating antigens; first antibodies produced in response to initial infection - Effective in causing agglutination (for example, blood type test) - Mostly in blood - First class of antibodies produced in the primary response (Note that other classes, such as IgG and so on, are
Factors contributing to the ability of bacteria to penetrate host defenses.
Factors contributing to the ability of bacteria to penetrate host defenses include capsules, certain cell wall components, enzymes, antigenic variation, and penetration into the host cell cytoskeleton.
True or False: Haptens can bind to antibody molecules only if the haptens are attached to a carrier molecule.
False
True or False: Macrophages and dendritic cells are the only cells that can present antigen to T cells.
False
True or False: The process of eliminating potentially self-reactive T cells in the thymus is called clonal selection.
False
True or False: Transmission of Plasmodium spp. (malaria) through a mosquito bite is an example of vehicle transmission.
False
True or False: Water can serve as a human reservoir of Vibrio cholerae.
False
Commensalism
Form of symbiosis. One organism benefits, other unaffected. Eg staphylococcus epidermidis on the skin.
Inactivated killed vaccines
Generally considered safe Required boosters Induce mostly humoral immunity (antibody production)
Immune cells that secrete cytokines and activate other immune cells are:
Helper T-cells
How do helper T-cells and cytotoxic T-cells work together?
Helper T-cells produce cytokines to activate other cells of the immune system.
Community immunity
Herd immunity
Antibodies are a part of which type of immunity?
Humoral
Which part of the adaptive immune response involves B cells?
Humoral
Differentiate cellular immunity and humoral immunity.
Humoral immunity is immunity brought about by protective molecules called antibodies. Antibodies combat foreign molecules that we refer to as antigens. Humoral immunity involves B lymphocytes, more commonly known as B cells, which remove viruses, bacteria and toxins from body tissue fluids and blood by recognizing antigens and making antibodies against them. T lymphocytes, or T cells, are the basis of cellular immunity. This form of immunity is also called cell-mediated immunity. T cells do not bind to antigens directly, but recognize antigenic peptides after they have been processed by phagocytic cells such as macrophages. Both T cells and B cells are found primarily in blood and lymphoid organs. The responses of cellular immunity center on attacking antigens that make their way inside cells, whereas humoral immunity responses are directed at antigens that are extracellular (such as in blood or other body fluids). This means that cellular immunity is generally best at fighting virus that have infected a cell, as well as some fungal and parasitic infections, which generally involve pathogens much larger than bacteria and viruses. Because humoral immunity fights invaders outside cells, its efforts tend to focus on bacteria and their toxins, as well as viruses before they penetrate the target cells. T cells (like B cells) respond to antigens by means of receptors on their surface - T cell receptors (TCRs). Contact with an antigen complementary to a TCR can cause certain types of T cells to proliferate and secrete cytokines rather than antibodies.
Which of the following is FALSE concerning type II (cytotoxic) hypersensitivity reactions? A. IgM and IgG antibodies bind to antigens on foreign cells. B. Macrophage activity may lead to additional cellular damage. C. They are responsible for transfusion reactions. D. IgE binds to mast cells or basophils.
IgE binds to mast cells or basophils.
Type I (Anaphylactic) Characteristics
IgE binds to mast cells or basophils; causes degranulation of mast cell or basophil and release of reactive substances such as histamine.
If a patient has been exposed to an antigen for the first time, which class of immunoglobulin appears first?
IgM
Which of these antibodies provides evidence of an active infection when present?
IgM
use(s) BCRs to recognize etitope. First step in clonal selection
Immature B cells
T cells
Immune cells that mature in the thymus; have certain receptors on surface; actively involved in immune response.
Which of the following is a characteristic of rheumatoid arthritis?
Immune complexes of IgM, IgG, and complement are involved.
Naturally Acquired Active Immunity
Immunity conferred when a person is infected with pathogens and recovered; may last a very long time, even a life time such as measles.
Vaccination
Immunization; the process of administering a vaccine to stimulate immunity for future protection.
Subclinical (inapparent) disease
Inapparent infection; does not cause any noticeable illness.
Development of infectious disease. Know fig 14.5
Incubation, prodromal period, period of illness, period of decline, period of convalescence N.b. A patient can be infectious during every stage; infection can be spread even during incubation and convalescence
Superantigens
Induce T cell proliferation and excessive release of cytokines by T cells that lead to fever, diarrhea, shock, etc. Example: staphylococcal toxins
Nosocomial infection
Infection acquired in health care facilities
What does inflammation stimulate?
Inflammation stimulates macrophages to produce cytokines, such as tumor necrosis factor-alpha (TNF-alpha), which leads to the synthesis of acute-phase proteins in the liver and activation of the inactive form of acute-phase proteins in the blood.
Which of the following is true concerning systemic anaphylaxis?
Injected antigens combine with IgE antibodies on the surface of certain cells, causing them to release histamines and other inflammatory mediators.
Includes cilia, mucous membranes, dendritic cells
Innate Immunity
Where do Salmonella pathogens grow and replicate in the infected host?
Inside phagocytes
Subacute disease
Intermediate between acute and chronic
Subacute disease
Intermediate between acute and chronic diseases.
These microbial surface proteins rearrange the host cell 19s actin filaments, allowing pathogens to enter and move in and between cells.
Invasins
Infection
Invasion and growth of pathogens in the body causing signs of illness, inflammation or tissue damage
Cell Wall Components
Involved in attachment to host cells and resistance to phagocytosis by the host.
How does the protozoan Trypanosoma evade detection by the immune system?
It can change the surface antigens frequently, preventing the immune system from tracking it.
LD50
Lethal dose for 50% of a sample population; indicates the potency of a toxin.
Endotoxins are also known as
Lipid A.
Chronic inflammation
Long lasting, less intense and more destructive. For example, tuberculosis in a chronic infection of Mycobacterium tuberculosis.
pH
Low pH either destroys microbes or inhibits the growth of microbes.
Lysozyme
Lysozyme, found in perspiration, tears, saliva, nasal secretions, tissue fluids and urine, can break the chemical bonds on peptidoglycan. Lysozyme is more effective against gram positive than gram-negative.
Based on the animation, T cells recognized the antigen displayed by what protein of the B cell?
MHC
Which proteins on the antigen-presenting cell are recognized by the helper T-cell?
MHC proteins
Epidemic disease
Many people in a given area get it in a relatively short period of time; influenza.
Epidemic disease
Many people in an area get it in a relatively short period of time. E.g. Influenza
Indirect Contact Transmission
Mediated through a nonliving object (termed a fomite) Contaminated syringes are fomites of HIV and hepatitis B
The student who caught the cold caused by this specific Rhinovirus was exposed to the exact same Rhinovirus 18 months later. What component of the immune system will protect her from getting the same cold again?
Memory B cells
differentiated B cells that are stored in lymph nodes to provide protection against future infections by the same pathogen
Memory cells
When a person has previously been vaccinated against a viral pathogen, which cells are activated if that same pathogen re-enters the host's cells months or years later?
Memory cytotoxic T cells
Droplet Transmission
Microbes in droplet nuclei (mucus droplets) discharged through coughing, sneezing, talking etc. and travel less than 1 meter Examples include cold, influenza, pneumonia and pertussis (whooping cough)
Systemic infection
Microorganisms or their products are spread throughout the body
Systemic (generalized) infection
Microorganisms or their products are spread throughout the body by blood or lymph
Systemic (generalized) infection
Microorganisms or their products are spread throughout the body by blood or lymph.
Transient microbiota
Microorganisms that are present in or on the body and then disappear
Structure of IgD
Monomer
Structure of IgE
Monomer
Structure of IgG
Monomer
A-B Toxins
Most exotoxins are A-B toxins Consist of polypeptide A (Active) and B (Binding) B components bind to cell receptors, and then A-B toxins enter the cell by receptor-mediated endocytosis. Once inside, A component disrupts cellular functions, such as inhibits protein synthesis of the host cell.
GI Tract
Most microbes are destroyed by the hydrochloric acid and enzymes in the stomach or by bile and enzymes in the small intestine; pathogens enter through this route are adapted to survive Poliomyelitis, hepatitis A, typhoid fever, amebic dysentery, giardiasis, shigellosis, and cholera
Cell-Mediated Autoimmune Reactions
Multiple Sclerosis Insulin-Dependent Diabetes Mellitus Psoriasis
Describe the characteristics and role of natural killer (NK) cells.
Natural killer cells are a component of the innate immune system. - No specificity - Do not need to be stimulated by an antigen - Destroy virus-infected cells, cancer cells, and parasites - Kill the target cell that does not express MHC Class I self-antigens
IgA Proteases
Neisseria gonorrhoeae and Neisseria meningitidis produce IgA proteases to destroy IgA antibodies by the host defense against adherence of pathogens to mucosal surfaces.
Meningitis and gonorrhea are caused by
Neisseria species.
Why would a body cell that is not a phagocyte need to present antigens?
Non-phagocytic body cells can become infected with a virus.
Sign
Objective changes the physician can observe and measure.
Sporadic disease
Occurs occasionally. E.g. typhoid fever in U.S.
Sporadic disease
Occurs occasionally; typhoid fever in the United States.
Interferons
One way an infected host cell counters viral infections is with a family of cytokines called interferons (IFNs). These are a class of proteins produced by certain animal cells, such as lymphocytes and macrophages. Interferons produced by people protect human cells, but they produce little antiviral activity for cells of other species, such as mice or chicken. However, the interferons of a species are active against a number of different viruses. They typically play a major role in infections that are acutes, such as colds and influenza. There are three main types of human interferons: gamma interferon (INF-y), alpha interferon (IFN-a), and beta interferon (IFN-b)
Opsonization
Opsonization, or immune adherence, promotes attachment of a phagocyte to a microbe. This enhances phagocytosis.
Opportunistic pathogens
Organisms that do not cause diseases in their normal habitat; however, may cause disease when they gain access to the other sites of the body
Focal infection
Originate from a local infection, later the pathogen or its products spread to the other parts of the body
Structure of IgM
Pentamer
Direct Contact Transmission
Person-to-person physical contact Examples include viral respiratory tract (cold, flu), staphylococcal infections, hepatitis A, measles, STD
Which structure do antigen presenting cells utilize to directly help them present bacterial antigens?
Phagolysosome
How can health care workers reduce the occurrence of nosocomial infections?
Practice more stringent aseptic techniques
Colonization
Presence & growth of microorganisms without signs or symptoms
Bacteremia
Presence of bacteria in the blood
Toxemia
Presence of toxins in the blood
Viremia
Presence of viruses in the blood
Kinins
Present in blood plasma. They attract neutrophils to the injured area.
Histamine
Present in mast cells in connective tissue, circulating basophils, and blood platelets.
Leukotrienes
Produced by mast cells and basophils. Help attach phagocytes to pathogens in addition to increase the permeability of blood vessels.
What cellular macromolecules make up the complement pathway?
Proteins
How is phagocytosis in the immune system different from protozoan phagocytosis?
Protozoan phagocytosis is used for feeding; phagocytosis by immune cells is used to fight infection.
Acute inflammation
Quick and intense. May result in the elimination of the cause and tissue repair, so acute inflammation is beneficial. For example, the response to a boil by Staphylococcus aureus.
Roles of plasmids in bacterial pathogenicity with examples
R (resistance factors): One group of plasmids, called R (resistance) factors, is responsible for the resistance of some microorganisms to antibiotics. In addition, a plasmid may carry the information that determines a microbe's pathogenicity. Examples of virulence factors that are encoded by plasmid genes are tetanus neurotoxin, heat-labile enterotoxin and staphylococcal enterotoxin D. Other examples include: dextransucrase, an enzyme produced by Streptococcus mutans that is involved in tooth decay Adhesins and coagulase produced by Staphylococcus aureus A type of fimbria specific to enteropathogenic strains of E. coli
Type IV (Delayed, Cell-Mediated, or Delayed Hypersensitivity) Examples
Rejection of transplanted tissues; contact dermatitis, such as poison ivy; certain chronic diseases such as tuberculosis
Symbiosis
Relationship between two organisms in which at least one is dependent on the other. (Communalism, mutualism, parasitism)
Prevalence
Represents the proportion of a population with the disease
Spread of infection
Reservoir of infection, transmission of disease ( contact, vehicle, vector)
Memory cells
Responsible for the faster and stronger secondary response, long lived. Each clone of B cells has the same specificity and only recognizes one specific antigen. The initial antibodies produced are IgM
mutation
Retroviruses, with reverse transcriptase step, have high mutation rate compared to DNA viruses. Lack proofreading. mutations are introduced at every position in HIV genome many times each day in infected person. creates problems of drug resistance and obstacles to development of vaccines and diagnostic tests.
What is the etiologic agent of typhoid?
Salmonella
Penetration into the Host cell Cytoskeleton
Salmonella typhimurium produces invasins that rearrange the host actin filaments, leads to the membrane ruffling, the bacterium sinks into the ruffle and is engulfed by the host cell. Shigella and Listeria use actin to propel through the host cytoplasm. Bacteria can also move from cell to cell via the cadherin of cell junctions.
Pathology
Scientific study of disease. Including etiology, pathogenesis, and the structural and functional changes and their effects on the body
Second Line of Defense
Second-line defenses slow or contain infections when first-line defenses fail. The include proteins that produce inflammation, fever that enhances cytokine activity, and phagocytes and NK cells, which attack and destroy cancer cells and virus-infected cells.
Location of IgA
Secretions (tears, saliva, mucus, intestine, milk), blood, lymph
Function of IgD
Serum function not known; presence on B cells functions in initiation of immune response.
Genitourinary Tract
Sexually transmitted infections
These proteins bind up iron obtained from the host cell 19s iron-transport proteins and transport this iron to bacteria through interactions with cell surface receptors.
Siderophores
Which of the following characteristics of a catheter should be considered, to help minimize the spread of nosocomial infections?
Single-use
Reservoir of infection
Sites, living or non living, where pathogens are maintained as a continual source of infection A) human carriers- people with signs or symptoms, or carriers w/no sign of illness B) animal reservoir- zoonoses are diseases transmitted from animals to humans C) nonliving reservoir - soil, water, foods
Hapten
Small, simple molecules that are not immunogenic (do not stimulate immune responses) unless combined with other molecules. They can be recognized and bound by specific antibodies. A substance of low molecular weight that does not cause the formation of antibodies by itself but does so when combined with a carrier molecule.
Describe the roles of phage DNA in bacterial pathogenicity with examples.
Some bacteriophages (viruses that infect bacteria) can incorporate their DNA into the bacterial chromosome, becoming a prophage, and thus remain latent and do not cause lysis of the bacterium. Such a state is called lysogeny, and cells containing a prophage are said to be lysogenic. One outcome of lysogeny is that the host bacterial cell and its progeny may exhibit new properties encoded by the bacteriophage DNA. Such a change in the characteristic of a microbe due to a prophage is called lysogenic conversion. As a result of lysogenic conversion, the bacterial cell is immune to infection by the same type of phage. Among the bacteriophage genes that contribute to pathogenicity are genes for: Diphtheria toxin Botulinum neurotoxin Capsule of Streptococcus pneumoniae Shiga toxin on E. coli 0157 Cholera toxin of Vibrio cholerae
resistance
Some people are exposed but never infected; they lack coreceptor CCR5. Some people never progress despite infection: these people have CD8+ T cells with unusual power to destroy fast-mutating viruses.
Adjuvant
Sometimes, a chemical is added to the vaccine to increase the immune response stimulated by the vaccine. The chemical is called adjuvant; adjuvant does not stimulate immune response.
Syndrome
Specific group of symptoms or signs that accompany a particular disease
Coagulases
Staphylococcus produces bacterial coagulase that convert fibrinogen to fibrin clot, which protects bacterium from phagocytosis and other host defense.
Examples of Biofilms
Streptococcus mutans attaches to teeth by glycocalyx and the fimbriae of Actinomyces adhere to the glycocalyx of Streptococcus mutans; these two form biofilm and contribute to dental plaque and dental caries (tooth decay).
Examples of bacteria producing capsules to increase virulence
Streptococcus pneumoniae Klebsiella pneumoniae Haemophilus influenzae Bacillus anthracis Yersinia pestis
Cell Wall Components Examples
Streptococcus pyogenes - M protein Neisseria gonorrhoeae - fimbriae and opa (an outer membrane protein) Mycobacterium tuberculosis - mycolic acid of cell wall
Kinases
Streptococcus pyogenes produces fibrinolysis (streptokinase) that breaks down fibrin clots formed by the host to confine the infection. Staphylococcus aureus produces staphylokinase
Epidemiology
Study of when and where diseases occur and how they are transmitted in populations Famous cases: 1) john snow- 1848/49, cholera in London 2) Ignacio Semmelweis- 1846/48, puerperal sepsis in Vienna 3) Florence nightingale- 1858, epidemic typhus in England
The Hepatitis B vaccine is which type of vaccine?
Subunit vaccine
What is the name for a vaccine that is made from an antigenic fragment of a pathogen?
Subunit vaccine
Erythrogenic toxin
Superantigens by Streptococcus pyogenes. They cause damages to the capillaries that lead to skin rash (scarlet fever)
How are superantigens different from other types of exotoxins?
Superantigens cause an overstimulation of the host immune system.
Immune Complex Autoimmune Reactions
Systemic Lupus Erythematosus Rheumatoid Arthritis
Generalized infection
Systemic infection
Which T cell is a component of both the cellular and humoral immune response?
T Helper cells
T cells
T cell defend against intracellular pathogens that are inside of the infected cell and not exposed to circulating antibodies. T cells also provide defense against cells with abnormal cell-surface markers such as cancer cells. T cells recognize antigens presented (bound) by the body's MHC via the antigen-binding sites on TCRs (T cell receptors). T cells originate from the stem cells in red bone marrow and mature in the thymus where the T cells that do not recognize the body's own MHC die. The majority of the T cells that recognizes that self-antigen presented by MHC also die. This is to ensure that the T cells can recognize the foreign antigens presented by the body's MHC.
Conjugated Vaccines
T-independent antigens, such as the capsular polysaccharides are poorly antigenic. Conjugate (combine) the polysaccharides with proteins, which results in enhanced immune response and better protection.
An antigen that is potent enough to activate a B cell on its own is known as
T-independent antigens.
T cytotoxic cells
TC cells; CD8+ cells; recognize foreign antigens presented by MHC Class i on APCs; activated T cytotoxic cells produce perforin (a pore-forming protein) and granzyme (protease, digests protein) that lead to apoptosis (cell death) of the targeted cells.
Which receptor on the helper T-cell recognizes the specific antigen from an antigen-presenting cell?
TCR
T helper cells
TH cells; CD4+ T cells. Recognize foreign antigen presented by MHC Class II on APCs (antigen presenting cells: macrophages, dendritic cells, and B cells); activated T helper cells produce cytokines that play roles in B cell activation, allergic reaction, inflammation and so on.
Which type of T cell is involved in activating macrophages and stimulating development of cytotoxic T cells?
TH1 cells
Natural killer cells are activated by
TH1 cells.
T regulatory cells
TR cells; formerly called T suppressor cells; CD4+ cells that also carry CD25; T regulatory cells keep adaptive immunity in check; thus prevent autoimmune disease, control inflammatory response and avoid targeting normal flora.
According to the animation, for approximately how many days is IgG present in the serum?
Ten days
Experimental epidemiology
Test a hypothesis concerning the cause of a disease
Experimental Epidemiology
Test a hypothesis concerning the cause of a diseases.
B cell activation
The B cell receptors (mostly IgM and IgD) recognize and bind to one particular epitope on antigen. There are numerous B cells that can recognize infinite numbers of antigens. Only one of the B cells with the receptors that recognize the particular epitope is activates; this is called clonal selection. The antigen is engulfed and processed, fragmented. MHC Class II (major histocompatibility complex) in the B cell bind to a fragment of the antigen and display it on B cell surface. The T helper cell receptor recognizes and interacts with the antigen-MHC Class II complex and is activated to produce cytokines, which activate B cells. Note: T cell receptor recognizes both the antigen portion and the MHC portion of the complex. Here, the antigen fragments are displayed on the B cell surface by the MHC Class II; therefore the B cell is an antigen-presenting cell.
If a person turns their ankle, how would one determine if damage to the tissue in the ankle has occurred?
The ankle is red, swollen, and warm to the touch.
Etiology
The cause of disease.
Complement System
The complement system consists of over 30 proteins produced by the liver that circulate in blood serum and within tissues throughout the body. The system is so named because it "completes" or assists cells of the immune system in destroying microbes. The complement system is not adaptable, never changing over a person's lifetime. Therefore, it is considered part of the innate immune system. However, it can be recruited into action by the adaptive immune system. Together, proteins of the complement system destroy microbes by cytolysis, opsonization and inflammation, and they also prevent excessive damage to the host tissues. Complement proteins are inactive until split into fragments (products), which activates them. Activated fragments carry out the destructive actions. Complement proteins are usually designated by an uppercase letter C, and are numbered C1 through C9, named in the order in which they were discovered. Complement proteins act in a cascade, where one reaction triggers another. More product is formed with each succeeding reaction in the cascade, amplifying the effects. The cascade of complement proteins that occurs during an infection is called complement activation. It may occur in three pathways that end in the activation of C3.
In the sixth segment of the animation, why is the disease epidemic in North America?
The disease occurs at a higher rate than what would normally be expected in this region.
Respiratory Tract
The easiest and most frequent Common cold, pneumonia, tuberculosis, influenza and measles
Period of decline
The immune response and the products of immune response peak in this stage
Incubation
The interval between the initial infection and the first appearance of signs or symptoms.
Local infection
The invading microorganisms are limited to a small area of the body
Local infection
The invading microorganisms are limited to a small area of the body.
Infection
The invasion and growth of pathogens in the body causing signs of illness, inflammation or tissue damage.
Period of illness
The most severe stage. Apparent signs and symptoms of the disease and usually when a patient goes to a physician. The immune system has not yet fully responded to the pathogens and the white blood cells may increase or decrease. The treatments and the patient's defense end the period of illness, or the patient dies during this period.
Mortality Rate
The number of deaths resulting from a disease in a given period of time in a population.
Incidence
The number of new cases of a disease in a population during a particular time period
Incidence
The number of new cases of a disease in a population during a particular time period. Indicates how common a disease occurs during the time period and is also an indicator of a person's probability of developing the disease during the time period.
Morbidity Rate
The number of people affected by a disease in a given period of time in a population.
Sebum
The oily substance produced by sebaceous (oil) glands functions as a protectant.
Knowing that rubella virus causes hemagglutination, you mix red blood cells, rubella virus, and a patient's serum in a tube. Hemagglutination does NOT occur. What do you conclude?
The patient has antibodies against rubella virus.
Bacteremia
The presence of bacteria in the blood.
Toxemia
The presence of toxins in the blood.
Viremia
The presence of viruses in the blood.
What is apoptosis?
The process of programmed cell death.
Artificially Acquired Active Immunity
The result of vaccination, which is the introduction of antigens into the body. For example, killed or live weakened pathogens or inactivated bacterial toxins. Provoke the body's immune response and provide long lasting protection.
Pathology
The scientific study of disease
Pathology
The scientific study of disease, including etiology (the cause of disease), pathogenesis (the way a disease develops) and the structural and functional changes and their effects on the body caused by the disease.
Period of Decline
The signs and symptoms subside. The immune response and the products of the immune system peak in this stage.
Airborne Transmission
The spread of pathogens by aerosol of small droplet nuclei that travel more than 1 meter Examples include measles and tuberculosis
What is a phagolysosome?
The structure that results from the fusion of a phagosome and a lysosome.
Epidemiology:
The study of when and where diseases occur and how they are transmitted in populations.
How do NK cells recognize the target cells that they will destroy?
The target cells lack MHC - I self antigen.
How do NK cells recognize the target cells that they will destroy?
The target cells lack MHC I self-antigen
What do the three pathways lead to?
The three pathways lead to the activation of C3, which in turn, can lead to cytolysis, opsonization and inflammation.
Leukocytosis
The total number of WBC (white blood cells) increases during infections, such as meningitis, infectious mononucleosis, appendicitis, pneumococcal pneumonia, gonorrhea.
Prevalence
The total number of cases of a disease in a population at a specified time
Prevalence
The total number of cases of a disease in a population at a specified time (either time point or time period. Represent the proportion of a population with the disease and is useful for assessing the impact of a disease in a population and a person's probability of having a disease.
ELISA (Enzyme-Linked Immunosorbent Assay)
The wells of a multi-well plate are coated with antibody Antigen is recognized by the antibody is then bound to the antibodies; thus, stay on the surface of the wells. Enzyme-linked antibody specific for the antigen is added and binds to the antigen; therefore, the enzyme-linked antibody stays in the well too. Next, substrate of the enzyme is added to the well. Enzyme converts substrate into a product that involves a color change; which can be monitored by a plate reader.
What direct effect do histamines and leukotrienes have on capillaries?
They allow capillary walls to open and become leaky.
How are immune cells able to detect foreign pathogens?
They are able to detect structures on the surfaces of foreign cells that are not found in the host.
First line defenses have what aspect in common with each other?
They are physical barriers against invading pathogens.
What is a feature of the small fragments presented by MHC-I proteins?
They are small peptides, roughly 8-10 amino acids long.
How do fibrinolysins enhance a pathogen's virulence?
They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.
How do Shigella cells move between host cells?
They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another.
How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system?
They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.
What is the role of opsonins?
They create "handles" that make it easier for the pseudopods of phagocytes to attach to the microbe invader.
What is the function of T cytotoxic cells?
They induce apoptosis of target cells. T cytotoxic cells can be activated to become cytotoxic lymphocytes (CTLs), which secrete perforin.
How do phagocytes communicate to other cells what they have captured?
They present antigens from engulfed foreign cells.
What is the fate of activated cytotoxic T-cells?
They proliferate into a clone of cells specific to the same antigen; some of these cells then differentiate into long-lived memory T-cells, while others mature to attack infected cells.
How can surgeons help to limit nosocomial infections?
They should perform surgeries and invasive procedures only when absolutely necessary.
Third Line of Defense
Third-line defenses include lymphocytes that target specific pathogens for destruction when the second-line defenses don't contain infections. It includes a memory component that allows the body to more effectively respond to the same pathogen in the future.
Period of convalescence
Tissues repaired; patient regains strength & recovers
Functions of inflammation
To destroy or remove the triggering agent(s), to confine the injurious agent(s) and to repair or replace the damaged tissue.
A direct agglutination test could be used for which of the following?
To detect antibodies against a bacterium
What is the role of epidemiology?
To learn how to treat and prevent various diseases.
What is the function of inflammation in response to a burn from a hot iron?
To repair the damaged tissue
Tom has a genetic disorder in which he does not synthesize class I MHC proteins or functional NK cells. Which of the following statements would be true for Tom?
Tom would not be able to destroy virally-infected cells.
Sepsis
Toxic inflammatory condition arising from the spread of microbes
These poisonous substances cause most of the damage to host cells; they can be transported by the blood or lymph and may produce far-reaching effects.
Toxins
Type II (Cytotoxic) Examples
Transfusion reactions, Rh incompatibility
Vehicle transmission
Transmitted by a medium such as water, food, air. 1) waterborne- cholera 2) foodbourne- hepA, parasitic worms 3) airborne- spread of pathogens by aerosol of small droplet nuclei, travel MORE than one meter. -e.g. Measles, TB
Isograft
Transplantation between identical twins
Allograft
Transplantation between people that are not identical twins
True or False: Helper T cells are involved in both the humoral and the cellular immune responses.
True
True or False: In biological transmission, pathogens reproduce in the vector.
True
True or False: T cells react to antigens on the surface of APCs only when those antigens are associated with proteins of the major histocompatibility complex.
True
True or False: Tetanus, which humans acquire from wounds that become infected with the soil microbe Clostridium tetani, is considered noncommunicable.
True
Alternative Pathway
Unlike the classical pathway, it does not involve antibodies. The alternative pathway is activated by contact between certain complement proteins and a pathogen.
Subunit vaccines
Use the antigenic fragments of a microbes to stimulate the immune response Can use recombinant DNA technology to produce large quantity of the antigenic fragments Safer as it is unlikely to be infected with a pathogen this way For example, the vaccine against Streptococcus pneumonia targets its capsule, the virulent factor that enables the bacteria resistant to phagocytosis. Toxoids vs. antitoxins Toxoids (inactivated toxins) of tetanus and diphtheria are included in the standard childhood immunization series followed by a booster every 10 years to stimulate immune response and maintain a sufficient level of protection. Antitoxin (antibodies against toxin) is used to treat patients suspected in danger of tetanus to provide immediate protection.
Prevalence
Useful for assessing the impact of a disease in a population
Period of illness
Usually a patient goes to a physician during this stage
Explain the principles and effects of vaccination
Vaccination stimulates a primary immune response against a pathogen, which results in the production of antibodies and long-term memory cells. A vaccinated individual is protected by the faster and stronger secondary immune response stimulated upon encounter with the pathogen later in life. Vaccination is especially useful in viral diseases since viral diseases usually cannot be effectively treated. When most of the population is immune to a disease, there are not many susceptible individuals to support the spread of the disease. This immunity in the population is called herd immunity.
Vector Transmission
Vectors are animals that transmit diseases from one host to another. Mechanical transmission: the vector passively carries the pathogens; however, it does not serve as hosts for the multiplication of pathogens. Biological transmission: the vector transmits pathogens and serves as host for the multiplication of pathogens.
Vector transmission
Vectors are animals that transmit diseases from one host to another. 1) Mechanical transmission- vector passively carries pathogens; however, it DOES NOT serve as hosts for the multiplication of the pathogens 2) Biological transmission- the vector transmits pathogens AND serves as host for the multiplication of the pathogens.
Live attenuated vaccines
Weakened live culture introduced and replicate in the body Introduce both humoral and cellular immunity since the pathogen reproduces in the host cells Lifelong immunity achieved without booster
Precipitation Reactions
When antibody and antigen are mixed in proper proportion, they form insoluble complexes called precipitates. For example, in immunodiffusion tests, antibody and antigen are set up on the opposite ends of the agar gel plate. The molecules diffuse; a band of antibody-antigen precipitates formed where antibody and antigen molecules meet.
When do helper T-cells develop into TH1 or TH2 cells?
When do helper T-cells develop into TH1 or TH2 cells? After proliferation into a clonal population
If a new bacterial pathogen entered a human body through an accidental needle stick, the first cell that would try to kill the pathogen would likely be
a phagocyte.
Fever
a second line of defense. Fever is an abnormally high body temperature and is a systemic response. The most frequent cause of fever is infection from bacteria or viruses.
The primary immune response involves
a slow rise in the concentration of antibodies, followed by a gradual decline.
Adherence
adhesion, the attachment of pathogens to their host tissue at their portal of entry.
An anamnestic response is
another name for secondary response.
Programmed cell death is referred to as
apoptosis
A vaccine consisting of a live avirulent strain of mumps virus is called an
attenuated vaccine.
Siderophores
bacterial iron-binding proteins. To obtain iron, some pathogens secrete proteins called siderophores. Siderophores are released into the medium, where they take the iron away from iron-transport proteins by binding the iron even more tightly. Once the iron-siderophore complex is formed, it is taken up by siderophore receptors on the bacterial surface. Then the iron is brought into the bacterium. In some cases, the iron is released from the complex to enter the bacterium, in other cases, the iron enters as part of the complex.
Infection Phase 1
billions of CD4+ T cells infected within a couple of weeks; viral numbers decline as fewer uninfected cells to target. Infection may be asymptomatic or causelymphadema
Which one of these diseases is noncommunicable?
botulism
In some cases, viral infections may __________.
cause cells to lose contact inhibition
CCR5
chemokine coreceptor necessary for HIV attachment
A new chemical messenger has been discovered that enhances the chemotaxis of macrophages and neutrophils toward sites of infection. It would be specifically classified as an ______________.
chemokine.
Cytokines that induce migration of leukocytes into areas of infection or tissue damage are known as
chemokines
coreceptors
chemokines named CCRS and CXCR4 that are found on T cell;, required along with CD4, in order for the HIV spikes to bind to T cells, the main target of HIV infection
The process by which a phagocyte moves toward a chemical signal at the site of an infection is called
chemotaxis.
Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage?
cholera
proviral DNA
chromosomal DNA of the host that also contains viral DNA
Antigenic stimulation of a particular B cell that results in the production of a large number of plasma and memory cells, all capable of responding to that antigen, is referred to as
clonal selection
Women who have a healthy population of Lactobacillus spp. as part of the normal vaginal microbiota are less likely to get yeast infections. Which of the following terms is used to explain this observation?
competitive exclusion
Second-line of defense
composed of cells (phagocytes), antimicrobial chemicals (the complement system, interferons, iron-binding proteins, and antimicrobial peptides), and process (inflammation and fever): many of these involved the components of blood
For the Hib vaccine, Haemophilus influenzae type b capsular polysaccharide is attached to a protein such as diphtheria toxoid. This attachment to the protein causes a better immune response against H. influenzae type b in infants. This Hib vaccine is a(n)
conjugated vaccine
When aerosols containing pathogens spread disease from a distance of less than one meter, it is considered
contact transmission.
You note that the body temperature of one of your patients is starting to increase. As a result, you can infer that all of the following may be occurring in this patient EXCEPT __________.
dilation of blood vessels
Infectious disease
disease directly caused by microorganisms and not by other means, for example, genetic or degenerative diseases
budding
enables viruses like HIV to exit the host cell; used by enveloped viruses which must acquire a host-derived membrane enriched in viral proteins to form their external envelope
Malaria is an infectious disease caused by infection with a protozoan. In certain tropical regions, malaria is constantly present. We would say that malaria is a(n) __________ disease in these regions.
endemic
In order to understand the full scope of a disease, we take its occurrence into account. The __________ of a disease is the number of people in a population who develop a disease at a specified time.
endemic infection prevalence
If a disease occurs at a fairly stable rate, it is said to be
endemic.
reverse transcriptase
enzyme that transcribe viral RNA into DNA
A rapid test for Bordetella pertussis uses fluorescent dye-labeled antibodies to stain a smear made from a nasopharyngeal swab. What would a positive test show?
fluorescent cells
Structure of HIV
genus Lentivirus is retrovirus; 2 identical strands RNA, enzyme reverse transcriptase, envelope of phospholipid; glycoprotein spikes termed gp120
spikes
glycoprotein on HIV envelope that must attach to T cell CD4 receptors
B cells interact directly with
helper T cells.
obstacles to HIV treatment
high mutation rate leading to resistant strains; persistence of latent viral reservoirs
immunological response brought about by antibody production
humoral immunity
Which of the following virulence factors is specifically involved in helping an organism to physically spread throughout the body?
hyaluronidase
Monoclonal antibodies are produced by
hybrid cells
Which of these disease stages is most likely to be altered in length if the number of infecting organisms at the start of the infection is very high?
incubation period
An infection transmitted by a hypodermic needle is transmitted by __________.
indirect contact
ID50
infectious dose for 50% of a sample population; indicates the virulence of a microbe.
Mucous membranes are a part of
innate defense.
Cell-mediated immunity in part protects against
intracellular bacteria and viruses.
Antigen processing and presentation
is a way for a cell to give information about its activities.
First-line defenses
keep pathogens on the outside to neutralize them before infection begins. The skin, mucous membranes and certain antimicrobial substance are the physical factors involved in theses defenses. Chemical factors (pH, lysozyme, sebum) and normal microbiota are also part of the first line of defense.
macrophages
macrophages and dendritic cells also carry CD4 receptors and are therefore another target of HIV infection
The symptoms of protozoan diseases are usually due to __________.
metabolic waste products
Parenteral route
microbes are deposited directly into the tissues when the skin or mucous membranes are penetrated or injured
Mucous Membranes
most pathogens enter through the mucous membrane of the gastrointestinal and respiratory tracts - Respiratory tract - GI tract - Genitourinary tract - Conjuctiva
An individual may be exposed to a pathogen and become infected without actually getting sick. This is known as a subclinical infection. Even in subclinical infections, the individual's adaptive immune system can generate memory for the pathogen. What type of adaptive immunity is this?
naturally acquired active immunity
The resistance to reinfection with measles virus following recovery from measles infection is called
naturally acquired active immunity.
Immunity acquired by transplacental transfer is called
naturally acquired passive immunity.
A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a(n)
neurotoxin.
Human reservoirs
people with signs and symptoms or carriers (show no signs of illness)
During the __________, a person recovers from a disease and the body returns to its pre-disease state. (three words)
period of convalescence
Live cultures of bacteria that can be ingested and are intended to produce a beneficial effect in humans are known as __________.
probiotic
Ingesting lactic acid bacteria to prevent colonization by intestinal pathogens such as Salmonella enterica during antibiotic therapy is an example of __________.
probiotics
CD4
receptor on T cell where HIV spikes attach
Plasmids
small, circular DNA molecules that are not connected to the main bacterial chromosome and are capable of independent replication.
Nonliving reservoir
soil, water, food
general infection notes
spread by dendritic cells, carried to lymphoid organs. contacts cells of immune system esp T cells and stimulates strong immune response. attachment via glycoprotein spike to CD4 receptor.
memory T cells
subset of HIV-infected cells, instead of veing killed, become long-lived memory T cells in which the reservoir of latent HIV can persist for decades. Shelters HIV from immune system
A person who attended a picnic early in the day develops a very high fever and is unresponsive by the evening. This person most likely has been exposed to a(n)
superantigen.
Measles viruses are capable of inactivating host defenses by
suppressing the immune system.
Which of these diseases does not have a human reservoir?
tetanus
Pathogenicity
the ability of microbes to cause disease.
Virulence
the capacity of a pathogen to invade and cause damage to the host; it's a measure of pathogenicity.
Antimicrobial chemicals
the complement system, interferons, iron-binding proteins, antimicrobial peptides.
Portals of entry
the entrance sites of pathogens. They include mucous membranes (respiratory tract, GI tract, genitourinary tract and conjunctiva), skin and parenteral route.
Expected prevalence of a disease is
the expected occurrence of a disease based on past observations.
Phagocytosis is defined as
the ingestion of solid material by a eukaryotic cell.
Skin
the larvae of hookworm enter the host by penetrating intact skin
Diapedesis is
the migration of phagocytes through blood vessels to the site of tissue damage.
Both the innate and adaptive defenses of the immune system work to prevent
the penetration and colonization by pathogens, and the diseases they cause.
HIV selectively destroys CD4 cells and as a result, a person with AIDS is susceptible to life-threatening infections with other types of viruses. Knowing this, you can conclude that
these other viruses have T-dependent antigens.
If a patient notices a healthcare worker not following suggested precautions,
they should immediately bring it to the attention of the healthcare worker.
transmission of HIV
transfer of or direct contact with infected bodily fluids. Blood, semen. No known transmission via saliva (kissing). Routes of transmission: sexual intercourse esp. analreceptive, breast milk, transplacental infection of fetus; needles, organ transplants, artificial insemination, blood transfusion. Oral-genital transmission rare but known.
Vehicle transmission
transmitted by a medium such as water, food or air (waterborne transmission, foodborne transmission and airborne transmission)
Which type of hypersensitivity is allergic contact dermatitis?
type IV reaction
Vector transmission
vectors are animals that transmit diseases from one host to another (mechanical transmission and biological transmission)
infectivity of HIV
viral DNA integrated into cellular DNA as provirus that later can be activated to produce infective viruses; once activated, final assembly takes place at cell membrane; macrophages can be latently infected with HIV persisting as a provirus or as a complete virion in a vacuole.
Certain traits that allow pathogens to create infection and cause disease are termed
virulence factors.
Cytopathic Effects of Viruses
visible effects of viral infection. Cytocidal effects are the cytopathic effects that result in death and non-cytocidal effects are the cytocidal effects that results in cell damage but not death. Potential cytopathic effects vary with disease but include: Stop host synthesis machinery, stop mitosis Destruction of intracellular contents and cell death Formation of inclusion bodies Formation of syncytium (cells fused to form a gigantic multinucleate cell) Reduce the production of cytokine, such as CD46 Induce the production of interferons Induce antigenic changes on the surface of infected cells Induces chromosomal changes Loss of contact inhibition (for mammalian cells, cell division stops when cell growth reaches a point where the culture forms a monolayer of cells with neighboring cells touching each other. Without contact inhibition, cells keep dividing out of control, which leads to cancer)
Leukocytes
white blood cells, two groups based on granules: granulocytes (have granules in cytoplasm) and Agranulocytes (no granules visible)
Blood flukes (schistosomes)
would most likely be attacked by antibody-dependent cell-mediated cytotoxicity. This is because antibody-dependent cell-mediated cytotoxicity operates against large pathogens.
Animal reservoir
zoonoses are diseases transmitted from animals to humans
