CCBC Microbiology 230 Unit 4 Exam (crossword, questions, clicker questions)

chronic viral infection EXAMPLE

hepatitis B virus (HBV), hepatitis C virus (HCV)

latent viral infection

herbes simplex type 1 virus (HSV-1), herpes simplex type 2 virus (HSV-2), Varicella-zoster virus (VZV)

slow viral infection

human immunodeficiency virus type 1 (HIV-1), human immunodeficiency virus type 2 (HIV-2)

_____ amantadine, rimantidine, zanamivar, and oseltamivir

influenza A

humoral immunity

involves the production of antibody molecules in response to an antigen and is mediated by B-lymphocytes when antibodies remove or neutralize microorganisms and their toxins after binding to their epitopes

cell-mediated immunity.

involves the production of cytotoxic T-lymphocytes, activated macrophages, activated NK cells, and cytokines in response to an antigens. These defense cells help to remove infected cells and cancer cells displaying foreign epitopes.

_____ Viral infections where the virus remains in equilibrium with the host for long periods of time before symptoms again appear, but the actual viruses cannot be detected until reactivation of the disease occurs.

latent viral infection

The host bacterium for a bacteriophage is called a ________________.

lysogen

State what type of cell monocytes differentiate into when they enter tissue.

macrophages

___________ the cells in the tissue whose primary function is to present antigen to effector T-lymphocytes

macrophages

_____________ the cells whose primary function is to release vasodilators such as histamine, leukotriens, and prostaglandins to promote inflammation.

mast cells (in defense)

pathogen-associated molecular patterns or PAMPs (PAMP)

molecules shared by groups of related microbes that are essential for the survival of those organisms and are not found associated with mammalian cells.

_____ Important in phagocytosis and aid in the adaptive immune responses; produce cytokines; 4%-8% of the leukocytes; differentiate into macrophages and dendritic cells when they leave the blood and enter the tissue.

monocytes

_____ Important phagocytes; 54%-75% of the leukocytes; granules stain poorly; produce enzymes for the synthesis of bradykinins and prostaglandins that promote inflammation.

neutrophils

_____ These drugs chemically resemble normal DNA nucleotides, the building block molecules for DNA synthesis. They bind to the active site of the reverse transcriptase which, in turn, inserts it into the growing DNA strand in place of a normal nucleotide. Once inserted, however, new DNA nucleotides are unable to attach to the drug and DNA synthesis is stopped. This results in an incomplete provirus.

nucleoside reverse transcriptase inhibitors

When a bacteriophage inserts its DNA into the DNA of the host bacterium, this form of the virus is called a ________________.

prophage

_____ These are drugs that bind to the active site of an HIV-encoded protease and prevent it from cleaving the long gag-pol polyprotein and the gag polyprotein into essential proteins essential to the structure of HIV and to RNA packaging within its nucleocapsid. As a result, viral maturation does not occur and noninfectious viral particles are produced.

protease inhibitors

PRRs (pattern recognition receptors)

receptors that recognize PAMPs

_____ foscarnet, gancyclovir, cidofovir, valganciclovir, and fomivirsen

severe CMV infections such as retinitis

_____ Viral infections in which the infectious agents gradually increase in number over a very long period of time during which no significant symptoms are seen.

slow viral infections

A virus capable of the lysogenic life cycle is called a __________________.

temperate phage

eclipse period

the period during viral multiplication when complete, infective virions are not yet present.

Name 3 herpes viruses that may have a latent cycle, state in what cell types they become latent, and name the diseases each cause.

- Herpes viruses, for example, are often latent in some cell types but productive in others. - Herpes viruses include: 1. herpes simplex type 1 (HSV-1) --> which usually causes fever blisters or oral herpes. 2. herpes simplex type 2 (HSV-2) --> which usually causes genital herpes. 3. Epstein-Barr virus (EBV) --> which causes infectious mononucleosis and plays a role in certain cancers. 4. varicella-zoster virus (VZV) --> which causes chickenpox and shingles. 5. cytomegalovirus (CMV) --> which causes a variety of infections in immunosuppressed persons and is also a leading cause of birth defects.

State why some bacteriophages are more complex than typical polyhedral or helical viruses.

- Some bacteriophages are structurally much more complex than typical nucleocapsid or enveloped viruses and may possess a unique tail structure composed of a base plate, tail fibers, and a contractile sheath. - Other bacteriophages, however, are simple icosahedrals or helical

Define viroid and name an infection caused by a viroid.

- They are small, circular, single-stranded molecules of infectious RNA lacking even a protein coat. - They are the cause of a few plant diseases such as: potato spindle-tuber disease, cucumber pale fruit, citrus exocortis disease, and cadang-cadang (coconuts).

We just learned that most viruses are much smaller than bacteria. 1. Compare the sizes of viruses and bacteria. 2. Why are viruses able to be so much smaller than bacteria?

- Viruses are usually much smaller than bacteria with the vast majority being submicroscopic - less genetic material

Compare the size of most viruses to that of bacteria.

- Viruses are usually much smaller than bacteria with the vast majority being submicroscopic. - While most viruses range in size from 5 to 300 nanometers (nm), in recent years a number of giant viruses, including Mimiviruses and Pandoraviruses with a diameter of 0.4 micrometers (µm), have been identified.

Define prion and name 3 protein misfolding diseases that appear to be initiated by prions.

- infectious protein particles responsible for a group of transmissible and/or inherited neurodegenerative diseases; referred to as transmissible spongiform encephalopathies. In humans: 1. Creutzfeldt-Jakob disease (mad cow) 2. kuru 3. Gerstmann-Straussler- syndrome In Animals: 1. Scrapie in sheep and goats 2. bovine spongiform encephalopathy (mad cow disease) in cattle

What is the difference between 1. CBC 2. leukocyte differential count?

1. A CBC or complete blood count determines the total number of leukocytes and erythrocytes per milliliter of blood. 2. A leokocyte differential count determines the number of each type of leukocyte calculated as a percentage of the total number of leukocytes.

Describe the 5 steps involved in the lytic life cycle of bacteriophages.

1. Adsorption. Attachment sites on the phage adsorb to receptor sites on cell wall, flagella, or pili of the host bacterium. 2. Penetration. In the case of phages that adsorb to the bacterial cell wall, a phage enzyme drills a hole in the bacterial wall and the phage injects its genome into the bacterial cytoplasm. This begins the eclipse period. The genome of phages which adsorb to flagella or pili enter through these hollow organelles. 3. Replication. The phage replicates its genome and uses the metabolic machinery of the bacterium to synthesize phage enzymes and phage structural components. 4. Maturation. The bacteriophage parts assemble around the phage genome. 5. Release. Usually, a phage-coded lysozyme breaks down the bacterial peptidoglycan causing osmotic lysis and release of the intact bacteriophages.

List 4 shapes of viruses.

1. Helical viruses consist of nucleic acid surrounded by a hollow protein cylinder or capsid and possessing a helical structure 2. Polyhedral viruses consist of nucleic acid surrounded by a polyhedral (many-sided) shell or capsid, usually in the form of an icosahedron; 3. Enveloped viruses consist of nucleic acid surrounded by either a helical or polyhedral core and covered by an envelope 4. Binal (complex) viruses have neither helical nor polyhedral forms, are pleomorphic or irregular shaped, or have complex structures

State 3 different functions of macrophages in body defense.

1. Killing of microbes, infected cells, and tumor cells by phagocytosis. 2. Processing antigens so they can be recognized by T-lymphocytes during the adaptive immune responses. 3. Secreting cytokines such as TNF-alpha, Il-1, Il-6, and Il-8 that play regulatory roles in body defense.

Name the 2 types of bacteriophage life cycles and state what the bacteriophage capable of each is called.

1. The lytic life cycle, carried out by lytic bacteriophages. 2. The lysogenic life cycle, carried out by temperate bacteriophages.

List 3 criteria used to define a virus.

1. The vast majority of viruses contain only one type of nucleic acid: DNA or RNA, but not both. 2. Viruses are totally dependent on a host cell for replication. (They are strict intracellular parasites.) 3. Viral components must assemble into complete viruses (virions) to go from one host cell to another.

2 nonliving characteristics of viruses

1. They are acellular, that is, they contain no cytoplasm or cellular organelles. 2. They carry out no metabolism on their own and must replicate using the host cell's metabolic machinery. In other words, viruses don't grow and divide. Instead, new viral components are synthesized and assembled within the infected host cell. 3. The vast majority of viruses possess either DNA or RNA but not both.

2 living characteristics of viruses

1. They reproduce at a fantastic rate, but only in living host cells. 2. They can mutate.

envelope

A phospholipid bilayer derived from host cell membranes, this structure typically surrounds a polyhedral or helical nucleocapsid.

Immunogen

A substance capable of inducing an immune response

bacteriophage

A viruse that infects only bacteria.

Describe how the retrovirus HIV-1 accomplishes each of the following steps during its life cycle. (Include the following key words in your description: gp120, CD4, chemokine receptors, gp41, capsid, RNA genome, reverse transcriptase, double-stranded DNA intermediate, provirus, polyproteins, proteases, and budding.) A. viral attachment or adsorption to the host cell B. viral entry into the host cell C. viral movement to the site of replication within the host cell and production of a provirus. D. viral replication within the host cell E. viral assembly or maturation within the host cell and release from the host cell

A. An envelope glycoprotein on the surface of HIV called gp120 adsorbs to first a CD4 molecule and then a chemokine receptor found on the surface of certain human cells such as T4-lymphocytes and macrophages. B. Once the gp120 interacts with both the CD4 molecule and the chemokine receptor on the surface of the host cell, the viral envelope is able to fuse with the host cell cytoplasmic membrane. After fusion of the viral envelope with the host cell cytoplasmic membrane, the genome-containing protein core of the virus enters the cytoplasm of the host cell. C. The ssRNA genomes are released from the capsid into the cytoplasm of the host cell. HIV now uses the enzyme reverse transcriptase to make a DNA copy of the RNA genome. As the DNA is being synthesized off of the RNA template, the enzyme degrades the viral RNA genome. Reverse transcriptase then makes a complementary DNA strand to form a double-stranded viral DNA intermediate. The double-stranded viral DNA intermediate now inserts into the chromosomes of the host cell to become a provirus. This is accomplished via a viral enzyme called integrase.. D. The Env polyproteins (gp160) are cleaved by proteases and are processed in the ER and the Golgi complex to produce molecules of the envelope glycoproteins gp41 and gp120. The gp41 anchors the gp120 in the plasma membrane of the host cell. Maturation either occurs in the forming bud or in the immature virion after it buds from the host cell. During maturation, HIV proteases will cleave the Gag and the Gag-Pol polyproteins into individual functional HIV structural proteins, enzymes, and regulatory proteins. The various structural components will then assemble around the ssRNA genomes to produce a mature HIV virion. The virus is released by budding from the host cell plasma membrane.

2. Zidovudine (AZT; Retrovir);lamivudine (3TC;Epivir); saquinavir (Inverase); idinavir (Crixivan); nelfinavir (Viracept); amprenavir (Agenerase) are used to treat: A. HIV. B. herpes viruses. C. influenza viruses. D. cytomegaloviruses.

A. HIV.

3. A virus adsorbs to receptors on a bacterium, injects its genome, uses the bacterium's metabolic machinery to produce viral parts and enzymes, assembles, and is released by host cell lysis. This best describes: A. The lytic life cycle of bacteriophages. B. The lysogenic life cycle of bacteriophages. C. The productive life cycle of proviruses.

A. The lytic life cycle of bacteriophages.

2. An antigen-specific defense mechanisms that take several days to become protective and are designed to react with and remove a specific antigen. This best describes: A. adaptive immunity. B. innate immunity. C. humoral immunity. D. cell-mediated immunity.

A. adaptive immunity.

4. The immunity one develops throughout life that allows us to recognize any antigen the body encounters. This best describes: A. adaptive immunity. B. innate immunity. C. humoral immunity. D. cell-mediated immunity.

A. adaptive immunity.

2. Viral infection where the virus remains in equilibrium with the host for long periods before symptoms again appear, viruses can be demonstrated in the body at all times, and the the disease may be present or absent for an extended period of time. This best describes: A. chronic infections. B. latent infections. C. slow infections. D. acute infections.

A. chronic infections.

2. HIV primarily infects memory T4-lymphocytes and dendritic cells, both expressing the chemokine receptor CCR5. The dendritic cells then carry HIV to regional lymph nodes. This best describes: A. early or acute HIV infection. B. chronic HIV infection. C. AIDS.

A. early or acute HIV infection.

7. HIV Env polyprotein is cleaved by protease into: A. gp120 and gp41. B. p17 and p24. C. integrase and reverse transcriptase.

A. gp120 and gp41.

2. HBV and HCV are associated with: A. liver cancer B. cervical cancer C. lung cancer D. lymphoma.

A. liver cancer

1. Bacteriophages that replicate through the lytic life cycle are called: A. lytic bacteriophages. B. temperate bacteriophages. C. prophages. D. lysogenic bacteriophage

A. lytic bacteriophages.

1. Leukocytes normally accounting for 54-75% of the WBCs and are primarily phagocytes; produce enzymes that promote inflammation. This best describes: A. neutrophils. B. eosinophils. C. basophils. D. monocytes. E. lymphocytes.

A. neutrophils.

6. To control the vast majority of viral infections we must rely on: A. the body's immune defenses. B. antibiotics. C. anti-viral drugs.

A. the body's immune defenses.

9. The HIV genome consists of : A. two molecules of single-stranded RNA. B. one molecule of double stranded DNA. C. one molecule of single stranded DNA. D. one molecule of double-stranded RNA

A. two molecules of single-stranded RNA.

2. HIV primarily infects: A.T4-lymphocytes, macrophages, and dendritic cells. B.T4-lymphocytes, endothelial cells, and epithelial cells. C. T4-lymphocytes, red blood cells, and neurons.

A.T4-lymphocytes, macrophages, and dendritic cells.

herpes

Acyclovir (Zovirax), famciclovir (Famvir), valacyclovir (Valtrex), and penciclovir (Denavir) are used to treat various ____________ viral infections

influenza

Amantadine (Symmetrel), rimantidine (Flumadine), zanamivir (Relenza), and oseltamivir (Tamiflu) are used to treat ______________ viruses.

provirus

An animal virus that has inserted its DNA into the Chromosomes of its host cell. During its life cycle, HIV becomes a Provirus.

antigen

An antigen is a substance that reacts with antibody molecules and antigen receptors on lymphocytes.

epitope

An epitope is the actual portion or fragment of an antigen that reacts with antibodies and lymphocyte receptors.

_____ Mediate humoral immunity (antibody production); have B-cell receptors (BCR) on their surface for antigen recognition; differentiate into antibody-secreting plasma cells.

B-lymphocytes

1. How does HIV adsorb to host cells? A. Gp120 on HIV adsorbs to a CD4 molecule on the host cell, then gp41 adsorbs to a chemokine receptor. B. Gp120 on HIV first adsorbs to a CD4 molecule on the host cell, then to a chemokine receptor.

B. Gp120 on HIV first adsorbs to a CD4 molecule on the host cell, then to a chemokine receptor.

1. The three viruses most commonly associated with human cancer are: A. HBV, HTLV-1, and EBV. B. HBV, HCV, and HPV. C. HPV, EBV, and HCV. D. HTLV-1, HCV, and VZV.

B. HBV, HCV, and HPV.

6. Most HIV genes are transcribed into mRNA molecules coding for: A. Individual HIV structural proteins. B. HIV polyproteins. C. HIV tRNA molecules. D. HIV toxins.

B. HIV polyproteins.

5. Have CD8 molecules and T-cell receptors on their surface for protein antigen recognition; differentiate into cytotoxic T-lymphocytes (CTLs). This best describes: A. NK cells. B. T8-lymphocytes. C. T4-lymphocytes. D. B-lymphocytes.

B. T8-lymphocytes.

3. A virus adsorbs to receptors on a bacterium, injects its genome, and either inserts into the host cell's chromosome or replicates within the host cell. This best describes: A. The lytic life cycle of bacteriophages. B. The lysogenic life cycle of bacteriophages. C. The productive life cycle of proviruses.

B. The lysogenic life cycle of bacteriophages.

4. A virus adsorbs to receptors on a bacterium, injects its genome, and either inserts into the host cell's chromosome or replicates within the host cell. This best describes: A. The lytic life cycle of bacteriophages. B. The lysogenic life cycle of bacteriophages. C. The productive life cycle of proviruses.

B. The lysogenic life cycle of bacteriophages.

4. HIV reverse transcriptase makes: A. an RNA copy of the HIV genome. B. a DNA copy of the HIV RNA genome. C. a double-stranded RNA copy of the single-stranded HIV RNA genome.

B. a DNA copy of the HIV RNA genome.

3. Certain strains of HPV are associated with: A. liver cancer B. cervical cancer C. lung cancer D. lymphoma

B. cervical cancer

3. Characterized by viral dissemination, viremia, and induction of adaptive immune responses. A steady state-infection generally persists where T4-lymphocyte death and T4-lymphocyte replacement by the body are in equilibrium. This best describes: A. early or acute HIV infection. B. chronic HIV infection. C. AIDS

B. chronic HIV infection.

2. During the lytic life cycle, bacteriophages are released from the host bacterium by: A. exocytosis. B. degrading peptidoglycan. C. budding.

B. degrading peptidoglycan

3. Acyclovir (Zovirax); famciclovir (Famvir); valacyclovir (Valtrex); penciclovir (Denavir) are drugs used to treat: A. HIV. B. herpes viruses. C. influenza viruses. D. cytomegaloviruses.

B. herpes viruses.

1. An antigen-nonspecific defense mechanisms that a host uses immediately or within several hours after exposure to almost any microbe. This best describes: A. adaptive immunity. B. innate immunity. C. humoral immunity. D. cell-mediated immunity

B. innate immunity.

3. The immunity one is born with and is the initial response by the body to eliminate microbes and prevent infection. This best describes: A. adaptive immunity. B. innate immunity. C. humoral immunity. D. cell-mediated immunity.

B. innate immunity.

5. Anti-HIV drugs that insert into the growing viral DNA strand in place of a normal nucleotide and block provirus formation are called: A. entry inhibitors. B. nucleoside-analog reverse transcriptase inhibitors. C. protease inhibitors.

B. nucleoside-analog reverse transcriptase inhibitors.

1. Bacteriophages capable of a lysogenic life cycle are termed: A. lytic bacteriophages. B. temperate bacteriophages. C. prophages. D. lysogenic bacteriophages.

B. temperate bacteriophages.

temperate bacteriophages

Bacteriophages capable of a lysogenic life cycle are termed ____________________.

1. The median incubation period for AIDS is approximately: A. 2 years. B. 5 years. C. 10 years. D. 20 years.

C. 10 years.

4. Marked by a viral load that progressively increases in number while the immune system weakens as a result of the destruction of increasing numbers of T4- lymphocytes and the inability of the body to continually replace these cells. A. early or acute HIV infection. B. chronic HIV infection. C. AIDS.

C. AIDS.

5. The HIV enzyme integrase inserting the double-stranded DNA intermediate of HIV into a host cell chromosome describes: A. How HIV replicates. B. How HIV kills T4-lymphocytes C. How HIV forms a provirus.

C. How HIV forms a provirus.

2. The DNA from a bacteriophage incorporated into the chromosome of a host bacterium is termed: A. a temperate bacteriophage. B. a lytic bacteriophage. C. a prophage. D. a lysogen.

C. a prophage.

2. Leukocytes that normally normally make up 0-1% of the WBCs . Primarily release histamine, leukotrienes, and prostaglandins - chemicals that promotes inflammation. This best describes: A. neutrophils. B. eosinophils. C. basophils. D. monocytes. E. lymphocytes.

C. basophils.

8. HIV proteases function to: A. degrade host cell proteins. B. insert HIV DNA into host cell chromosomes. C. cleave HIV polyproteins into individual, functional proteins.

C. cleave HIV polyproteins into individual, functional proteins.

1. Derived from monocytes, located throughout the epithelium of the skin, the respiratory tract, and the gastrointestinal tract, capture and present protein antigens to naive T-lymphocytes. This best describes: A. eosinophils. B. neutrophils. C. dendritic cells. D. macrophages. E. mast cells.

C. dendritic cells.

10. Most maturation of HIV occurs: A. in the host cell's nucleus. B. in the host cell's cytoplasm. C. during or after budding from the host cell. D. in the ER of the host cell.

C. during or after budding from the host cell.

1. Rimantidine (Flumadine); zanamivir (Relenza); oseltamivir (Tamiflu) are drugs used to treat: A. HIV. B. herpes viruses. C. influenza viruses. D. cytomegaloviruses.

C. influenza viruses.

4. Anti-HIV drugs that prevent HIV from making functional proteins from polyproteins are called: A. entry inhibitors. B. nucleoside-analog reverse transcriptase inhibitors. C. protease inhibitors.

C. protease inhibitors.

6. Mediate humoral immunity (the production of antibody molecules), have BCRs on their surface, differentiate into plasma cells. This best describes: A. NK cells. B. T8-lymphocytes. C. T4-lymphocytes. D. B-lymphocytes.

D. B-lymphocytes.

1. Viral infections that are of relatively short duration with rapid recovery are called: A. chronic infections. B. latent infections. C. slow infections. D. acute infections

D. acute infections

3. HIV enters T4-lymphocytes by gp41-mediated: A. endocytosis. B. exocytosis. C. budding. D. fusion of the viral envelope with the host cell's cytoplasmic membrane

D. fusion of the viral envelope with the host cell's cytoplasmic membrane

2. Killing of microbes, infected cells, and tumor cells by phagocytosis, processing antigens so they can be recognized by T-lymphocytes, and secrete cytokines. This best describes: A. eosinophils. B. neutrophils. C. dendritic cells. D. macrophages. E. mast cells.

D. macrophages.

3. Leukocytes that normally make up 2-8% of the WBCs, are phagocytes, and differentiate into macrophages and dendritic cells when they enter the tissue describes: A. neutrophils. B. eosinophils. C. basophils. D. monocytes. E. lymphocytes

D. monocytes.

early or acute HIV infection

During early or acute HIV infection the virus primarily infects and destroys memory T4-lymphocytes which express the chemokine receptor CCR5 and are very abundant in mucosal lymphoid tissues. Here HIV also encounters and infects the dendritic cells located throughout the epithelium of the skin and the mucous membranes.

lysogenic

During the __________________ life cycle, bacteriophage can either replicate by means of the lytic life cycle and cause lysis of the host bacterium, or, it can incorporate their DNA into the bacterium's DNA and become a noninfectious prophage.

chronic

During this phase of HIV infection, the lymph nodes and the spleen become sites for continuous viral replication and host cell destruction. During most of this phase, the immune system remains active and competent and there are few clinical symptoms. A steady state-infection generally persists where T4-lymphocyte death and T4-lymphocyte replacement by the body are in equilibrium.

acute

During this phase of HIV infection, the virus primarily infects and destroys memory T4-lymphocytes which express the chemokine receptor CCR5 and are very abundant in mucosal lymphoid tissues.

4. Leukocytes that normally represent 25-40% of the WBCs, circulate between the blood and lymphatics, and mediate adaptive immunity. This best describes: A. neutrophils. B. eosinophils. C. basophils. D. monocytes. E. lymphocytes.

E. lymphocytes.

3. Located in the connective tissue and throughout the mucous membranes. Contain inflammatory mediators like histamine, eosinophil and neutrophil chemotactic factor, and platelet activating factor. This best describes: A. eosinophils. B. neutrophils. C. dendritic cells. D. macrophages. E. mast cells.

E. mast cells.

_____ AZT (ZDV), didanosine, zalcitabine, stavudine, nevirapine, delavirdine, saquinavir, and ritonavir

HIV infection and AIDS

Name 3 types of cells HIV primarily infects and briefly explain why

HIV primarily infects T4-lymphocytes, monocytes, macrophages, and dendritic cells. These cells possess both the CD4 molecules and the chemokine receptors needed for adsorption of HIV.

_____ acyclovir, famciclovir, penciclovir, and valacyclovir

HSV and VZV infections

Name the 3 most common viruses that have been implicated in human cancers.

Hepatitis B virus (HBV) Hepatitis C virus (HCV) Human Papilloma viruses (HPV)

persistent

In _____________ infections, the viruses are continually present in the body

latent

In a___________ viral infection the virus remains in equilibrium with the host for long periods of time before symptoms again appear, but the actual viruses cannot be detected until reactivation of the disease occurs. Examples include infections caused by HSV-1 (fever blisters), HSV-2 (genital herpes), and VZV (chickenpox-shingles).

Prions

Infectious protein particles thought to be responsible for a group of transmissible and/or inherited neurodegenerative diseases.

Describe the process of lysogenic conversion and give 2 examples of exotoxins that result from lysogenic conversion.

LYSOGENIC CONVERSION: The added DNA of a prophage may occasionally give a bacterium a new genetic trait such as the ability to produce an exotoxin. Examples of exotoxins produced by bacteria as a result of lysogenic conversion include the diphtheria exotoxin, streptococcal pyrogenic exotoxin (Spe), the exfoliatin toxin of scalded skin syndrome, the botulism exotoxin, and the choleragen toxin of cholera.

State why antibiotics are of no use against viruses and what we must rely on to control viruses.

Many antibacterial antibiotics inhibit peptidoglycan synthesis in bacteria, BUT viruses do not contain peptidoglycan. Some antibacterial antibiotics alter cytoplasmic membranes, BUT viruses are not cells and lack cytoplasmic membranes. Some antibacterial antibiotics alter prokaryotic ribosomal subunits BUT viruses have no ribosomes. THEREFOR: Viruses lack the structures and functions that antibiotics affect.

naked

Most ___________ viruses are released by host cell lysis.

Describe what an animal virus consists of structurally.

Most animal viruses also have an envelope surrounding a polyhedral or helical nucleocapsid, in which case they are called enveloped viruses. The envelope is composed of phospholipids and glycoprotein.

ergosterol

Most antifungal drugs work by either binding to or inhibiting the synthesis of this molecule in its cytoplasmic membrane.

_____ Lymphocytes that lack B-cell receptors and T-cell receptors; kill cells to which the antibody IgG has attached as well as human cells lacking MHC-I molecules on their surface.

NK cells

Briefly describe how opsonizing antibodies can promote phagocytosis of viruses and how antibodies made against viral surface antigens can block adsorption of viruses to host cell receptors.

One of the major defenses against free viruses is the immune defenses' production of antibody molecules against the virus. The "tips" (Fab portion) of the antibody have shapes that have a complementary shape to portions of viral attachment proteins and glycoproteins called epitopes found on the viral surface. When antibodies react with these attachment proteins, they block viral adsorption to host cell receptors and, therefore, block viral replication.

State the major difference between the productive life cycle of animal viruses and the latent life cycle

Productive life cycle is an active animal virus, which can cause harm to the host. Latent is an inactive form.

In terms of viral load, exhaustion of the lymphopoietic system, and immune responses, briefly describe what marks the progression to AIDS

Progression to AIDS is marked by a viral load that progressively increases in both number and, through the high mutation rate of HIV, immunoresistance while the immune system weakens as a result of the destruction of increasing numbers of T4-helper lymphocytes, interleukin-4 induced suppression of the adaptive immune responses needed to remove HIV and kill HIV-infected cells, and the inability of the body to continually replace these destroyed cells. As the HIV level increases and the number of T4-lymphocytes decreases, the person progresses to full blown AIDS.

A viral enzyme that synthesizes a complementary RNA copy of an RNA would be called what?

RNA-Dependant RNA-ppolymerase

Regarding the naming of enzymes involved in the replication of viral nucleic acid, state what the "dependent" part of the name refers to and what the "polymerase" part of the name refers to.

Regarding the enzymes involved in nucleic acid replication: - the "dependent" part of the name refers what type of nucleic acid is being copied. - The "polymerase" part of the name refers what type of nucleic acid is being synthesized, e.g., DNA-dependent RNA-polymerase would synthesize a strand of RNA complementary to a strand of DNA.

Discuss why bacteria can be cultivated on synthetic media such as nutrient broth whereas viruses cannot.

Since viruses lack metabolic machinery of their own and are totally dependent on their host cell for replication, they cannot be grown in synthetic culture media. Animal viruses are normally grown in animals, embryonated eggs, or in cell cultures where in animal host cells are grown in a synthetic medium and the viruses are then grown in these cells.

Viroids

Small, circular, single-stranded molecules of infectious RNA lacking even a protein coat. They are the cause of a few plant diseases.

M-tropic

Strains of HIV that usually transmits the infection from person-to-person and infects monocytes, macrophages, dendritic cells, and T4-memory cells. (2 words)

_____ Regulate the adaptive immune responses through cytokine production; have CD4 molecules and TCRs on their surface for antigen recognition.

T4-lymphocytes

_____ Carry out cell-mediated immunity; have CD8 molecules and TCRs on their surface for antigen recognition; differentiate into cytotoxic T-lymphocytes (CTLs).

T8-lymphocytes

epitope

The actual portions or fragments of an antigen that react with antibodies and with receptors on B-lymphocytes and T-lymphocytes

Adsorption

The binding of attachment sites on the viral surface with receptor sites on the host cell cytoplasmic membrane.

chronic HIV infection

The chronic phase of HIV infection is characterized by viral dissemination, viremia, and induction of adaptive immune responses. The viremia allows the viruses to spread and infect T4-helper lymphocytes, macrophages, and dendritic cells found in peripheral lymphoid tissues.The lymph nodes and the spleen become sites for continuous viral replication and host cell destruction. During most of this phase, the immune system remains active and competent and there are few clinical symptoms. A steady state-infection generally persists where T4-lymphocyte death and T4-lymphocyte replacement by the body are in equilibrium.

protease

The enzyme HIV uses during maturation to split its 3 major polyproteins into functional proteins.

integrase

The enzyme that enables the double-stranded viral DNA intermediate of HIV to enter the host cell's nucleus and insert into one of the host cell's chromosomes to become a provirus.

Phagocytosis

The ingestion of solid particles by endocytosis.

State the median incubation period for AIDS

The median incubation period for AIDS is around 10 years.

maturation

The process where the viral capsid is assembled around the viral genome.

uncoating

The process where the viral genome is released from the remainder of the virus.

capsid

The protein shell surrounding the viral genome that is usually composed of protein subunits called capsomeres. This structure serves to protect and introduce the genome into host cells.

Capsomere

The protein subunits composing a viral capsid

toxoplasmosis

This protozoan disease is contracted by inhaling or ingesting cysts from the feces of infected domestic cats, or by ingesting raw meat of an infected animal. It is usually mild in people with normal immune responses but can infect the brain, heart, or lungs of people who are immunosuppressed. It can also be transmitted congenitallyand infect the nervous system of the infected child.

malaria

This protozoan disease is transmitted by the bite of an infected female Anopheles mosquito. The protozoa reproduce asexually by schizogonyin human liver cells and red blood cells but also reproduce sexually by gametes in the mosquito.

What are the criteria used in viral classification [need help --]

Viruses can store their genetic information in six different types of nucleic acid which are named based on how that nucleic acid eventually becomes transcribed to the viral mRNA.

viremia

Viruses in the blood.

Describe how certain viruses may contribute to the development of tumors by altering proto-oncogenes or tumor-suppressor genes

Viruses may cause long term damage to tissues resulting in large scale cell regeneration which increases the chances of natural mutation in proto-oncogenes and tumor suppressor genes, as in the case of HBV and HCV. Directly, by integrating into the chromosomes of the host cell, some viruses may alter the normal function of the proto-oncogenes and tumor suppressor genes, as is seen with HPV and HBV.

Nucleocapsid

Viruses that consist of no more than a genome surrounded by a capsid

Define bacteriophage.

Viruses that infect only bacteria

Describe the lysogenic life cycle of temperate phages (including spontaneous induction).

When a temperate phage infects a bacterium, it can either replicate by means of the lytic life cycle and cause lysis of the host bacterium, or, it can incorporate its DNA into the DNA of the host bacterium and become a noninfectious prophage. In about one out of every million to one out of every billion bacteria containing a prophage, spontaneous induction occurs. During spontaneous induction, the phage genes are activated and new phages are produced by the lytic life cycle. [Lysogenic --> DNA/Non-Infectious Phage --> spontaneous induction/activation --> lytic]

proviral

When the viral DNA is incorporated into the host cell's DNA.

lytic bacteriophages

________ bacteriophages, routinely lyse the host bacterium as a normal part of their life cycle.

Slow infections

__________ viral infections are ones in which the infectious agents gradually increase in number over a very long period of time during which no significant symptoms are seen. Examples include AIDS (caused by HIV-1 and HIV-2) and certain lentiviruses that cause tumors in animals.

innate immunity

___________ _____________ refers to antigen-nonspecific defense mechanisms that a host uses immediately or within several hours after exposure to an antigen. This is the immunity one is born with and is the initial response by the body to eliminate microbes and prevent infection.

adaptive (acquired) immunity

___________ _____________, refers to antigen-specific defense mechanisms that take several days to become protective and are designed to remove a specific antigen. This is the immunity one develops throughout life.

enveloped

_______________ viruses obtain their envelopes from host cell membranes by budding.

antigen

a molecular shape that reacts with antigen receptors on lymphocytes to initiate an adaptive immune response.

Capsid

a protein shell surrounding the genome and is usually composed of protein subunits called capsomeres.

When given information about a virus in terms of how it penetrates the host cell, whether it has a DNA or RNA genome, and how it is released, describe how an enveloped virus accomplishes each of the steps of the productive life cycle listed below. (Tailor the life cycle to that virus.) A. viral attachment or adsorption to the host cell B. viral entry into the host cell C. viral movement to the site of replication within the host cell D. viral replication within the host cell E. viral assembly or maturation within the host cell F. viral release from the host cell

a. Glycoproteins on the viral envelope adsorb to the receptors on the host cell membrane. b. In the case of some viruses, the viral envelope may fuse with the host cell cytoplasmic membrane and the nucleocapsid is released into the cytoplasm. Many enveloped viruses enter by endocytosis, whereby the host cell cytoplasmic membrane invaginates and pinches off, placing the virus in an endocytic vesicle. c. Fusion of the viral envelope with the membrane of the endocytic vesicle enabling the viral nucleocapsid to enter the cytoplasm of the host cell. Lysis of the endocytic vesicle releasing the viral nucleocapsid into the cytoplasm of the host cell. d. The viral genome directs the host cell's metabolic machinery (ribosomes, tRNA, nutrients, energy, enzymes, etc.) to synthesize viral enzymes and viral parts. The viral genome is transcribed into viral mRNA that goes to the host cell's ribosomes where it is translated into viral structural proteins and viral enzymes. During the early phase of replication, the viral genome replicates thousands of times. During the late phase of replication, viral structural proteins (capsid and matrix proteins, envelope glycoproteins, etc.) and the enzymes involved in maturation are produced. Also during this time, envelope glycoproteins coded by the viral genome of enveloped viruses are incorporated into the host cell's membranes. e. During maturation, envelope glycoproteins are transported to the cytoplasmic membrane of the host cell and the capsid assembles around the viral genome. Through budding and exocytosis. f. Viruses obtaining their envelope from the cytoplasmic membrane are released during the budding process. Viruses obtaining their envelopes from the membranes of the nucleus, the endoplasmic reticulum, or the Golgi apparatus are then released by exocytosis via transport vesicles.

When given information about a virus in terms of how it penetrates the host cell, whether it has a DNA or RNA genome, and how it is released, describe how a naked virus accomplishes each of the steps of the productive life cycle listed below. (Tailor the life cycle to that virus.) A. viral attachment or adsorption to the host cell B. viral entry into the host cell C. viral movement to the site of replication within the host cell D. viral replication within the host cell E. viral assembly or maturation within the host cell F. viral release from the host cell

a. Proteins in the viral capsid bind to the complementary receptors on the host cell membrane. b. In the case of naked viruses entering by capsid reconfiguration, interaction between the viral capsid and the host cell cytoplasmic membrane causes a rearrangement of capsid proteins allowing the viral nucleic acid to pass through the membrane into the cytoplasm. Most naked viruses enter by receptor-mediated endocytosis whereby the host cell cytoplasmic membrane invaginates and pinches off, placing the virus in an endocytic vesicle c. the viral capsid undergoes conformational changes that forms pores in the endocytic vesicle enabling the virial genome to enter the cytoplasm of the host cell. Before viruses can replicate within the infected host cell, the viral genome needs to released from the remainder of the virus. This process is sometimes referred to as uncoating d. The viral genome directs the host cell's metabolic machinery (ribosomes, tRNA, nutrients, energy, enzymes, etc.) to synthesize viral enzymes and viral parts. The viral genome is transcribed into viral mRNA that goes to the host cell's ribosomes where it is translated into viral structural proteins and viral enzymes. During the early phase of replication, the viral genome replicates thousands of times. During the late phase of replication, viral structural proteins (capsid and matrix proteins, envelope glycoproteins, etc.) and the enzymes involved in maturation are produced. Also during this time, envelope glycoproteins coded by the viral genome of enveloped viruses are incorporated into the host cell's membranes. e. During maturation, the capsid assembles around the viral genome. f. Naked viruses are predominantly released by host cell lysis. While some viruses are cytolytic and lyse the host cell more or less directly, in many cases it is the body's immune defenses that lyse the infected cell.

In terms of the role of cytotoxic T-lymphocytes (CTLs) in body defense: a. Describe how they can react with and destroy virus-infected cells, cells containing intracellular bacteria, and cancer cells. (Indicate the role of following: TCR, CD4, MHC-I, and peptides from viral antigens.)

a. Virus-infected host cells naturally bind viral epitopes to a host molecule called MHC-I and place the MHC-1 with a bound viral epitope on the surface of the infected cell where they can be recognized by CTLs having T-cell receptors on its surface with a complementary shape.

_____ Viral infections of relatively short duration with rapid recovery.

acute viral infections

innate immunity

an antigen-nonspecific defense mechanisms that a host uses immediately or within several hours after exposure to almost any microbe. This is the immunity one is born with and is the initial response by the body to eliminate microbes and prevent infection.

adaptive immunity

antigen-specific defense mechanisms that take several days to become protective and are designed to react with and remove a specific antigen. This is the immunity one develops throughout life.

In terms of the role of cytotoxic T-lymphocytes (CTLs) in body defense: b. State the mechanism by which cytotoxic T-lymphocytes kill the cells to which they bind.

b. In this way the CTL can kill the infected cell by apoptosis, a programmed cell suicide.

_____ Not important in phagocytosis; large granules stain a purplish blue; 0%-1% of the leukocytes; release histamine, leukotriens, and prostaglandins to promote inflammation

basophils

State 2 functions of platelets.

blood clotting and homeostasis

_____ Viral infections where the virus can be demonstrated in the body at all times and the disease may be present or absent for an extended period of time.

chronic viral infections

acute viral infection EXAMPLE

cold viruses, influenza viruses, rotaviruses, Norwalk virus

__________ the cells in the tissue whose primary function is to capture and present protein antigens to naive T-lymphocytes

dendritic cell

Describe how most animal viruses obtain their envelope.

derived from host cell membranes by a process called budding

______ work by preventing HIV from entering healthy CD4 cells (T-cells) in the body.

entry inhibitors

_____ Capable of phagocytosis but primarily kill microorganisms and parasitic worms extracellularly; 1%-4% of the leukocytes; large granules stain red; secrete leukotriens and prostaglandins to promote inflammation.

eosinophils