Human Microbiology test 5

What is a prophage?

When DNA integrates with bacterial DNA

What is a Hemolysis?

toxin: Lyse red blood cells and some lyse WBC, produced by gm+ cocci and Clostridium perfringens.

Lysogenic pathway in bacteriophage replication.

1. Attachment: cell wall and penetration (inject). 2. Can then continue with lytic cycle OR 3. DNA sometimes integrates with bacterial DNA (Prophage): - Bacteria can reproduce normally - Phage conversion can happen - Viral DNA excises from bacterial DNA and then continues with lytic cycle.

Define vaccine

Nontoxic antigen (Ag) injected to induce artificial specific defense - can be life long - prevent the disease from occuring

Describe polysaccharide vaccines.

Not as immunogenic as proteins Conjugate vaccine - bind polysaccharide to protein (toxoid) Mostly used for pneumonia causing bacteria.

Lytic pathway in bacteriophage replication.

1. Attachment: phage attaches to host cell wall. 2. Penetration: penetrates cell via phage lysozyme and injects DNA. 3. Biosynthesis: Phage DNA directs synthesis of viral components by host cell- eclipse period. 4. Maturations: Components assembled into virions. 5. Release: Cell lyses (Phage lysozyme) and virions released.

What are the four main ways that bacteria resist or not stimulate host defenses?

1. Capsules 2. Exoenzymes or toxins produced 3. Structural proteins 4. Mycolic acid

What is an exoenzyme?

An enzyme that acts outside the cell wall that produces it.

What is a viroid and what do they cause?

Short pieces of naked RNA 300-400 nucleotides long, no protein coat - causes plant diseases.

What is a Kinase?

dissolve clots that body forms to isolate infection, keeps body from trapping bacteria behind clots, produced by gram+ cocci

What are the major steps for lytic bacteriophage infection, also describe these?

1. Attachment: Phage attaches to host cell wall. 2. Penetration: penetrates cell via phage lysozyme and injects DNA. 3. Biosynthesis: Phage DNA directs synthesis of viral components by host cell - eclipse period. 4. Maturation: Components assembled into virions. 5. Release: Cell lyses (phage lysozyme) and virions released

What are some prevention methods (vaccine information)?

*Get the vaccine *Wash hands often with soap and water *Avoid touching your eyes, nose or mouth *Cover your nose and mouth when coughing/sneezing *Avoid close contact with sick people. *If your sick stay at home for 24 hours after fever is gone.

Discuss some issues with the Wakefield study. What has been some of the consequences of this study?

*He only used 12 patients for the case study, not a lot of people like need be. *He paid solicitors representing parents to conduct the study. *His license to practice medicine was stripped in 2011 because he "acted dishonestly and irresponsibly in failing to disclose...how patients were recruited for the study."

List the cytopathic effects of viral infection.

1. Change the growth of the host cell 2. Cause lysosomes to dump digestive enzymes inside the cell 3. Inclusion bodies form granules of viral parts in cytoplasm or nucleus of cell. 4. Syncytium form - are large multinuclear cells due to cell fusing together. 5. Changes in host cell function 6. Interferons produced by infected cells as part of immune response. 7. Antigen changes on cell surface 8. Activation of oncogenes 9. Loss of contact inhibition

Note and describe the six specific examples of exotoxins?

1. Diphtheria toxin: inhibits protein synthesis. 2. Erythrogenic toxin: damage blood capillaries which causes red skin rash 3. Botulism toxin: neurotoxin that prevents transmission of impulses from nerve to muscle. 4. Tetanus toxin: neurotoxin that blocks the relaxation pathway of muscle contraction. 5. Vibrio enterotoxin: causes the discharge of fluids and electrolytes in the small intestine. 6. Staphylococcus enterotoxins: similar to vibrio to enterotoxin and toxic shock syndrome.

How is the disease organism transmitted?

1. Droplet - respiratory tract (50,000-500,000 virus/droplet) 2. Fomites - nonliving object - spread infection - touch nose/mouth

List three ways that prions are transmitted.

1. Eating CNS from an infected animal 2. Transplanting nerve tissue. 3. Contaminated surgical instruments - hard to degrade enzymes or heating

What are 4 responses of the body to endotoxins?

1. Immune response of macrophage releasing lots of cytokins - lots are toxic. 2. Activation of small blood clotting > blocks capillaries > death of tissues 3. Fever- inhibit bacterial growth 4. Septic shock - shock caused by bacteria.

List and describe the three main types of influenza.

1. Influenza A: broken into subtypes based on glycoproteins present - hemaglutinin and neuraminidase, subtypes broken into strains, cause of major pandemics 2. Influenza B: infects humans only (geographic epidemic), broken into strains 3. Influenza C: No epidemics - mild disease, infects humans and pigs

What are some of the animal viruses life cycles?

1. Lytic: same that phage does 2. Latent: virus remain in host for long periods w/o producing disease ("repressed" state) - reactivates - herpes virus. 3. Persistent or slow: small amount of virus always found - like HIV

What are the three main portals of entry?

1. Mucous membranes 2. Skin 3. Parenteral route

What are some antiviral drugs which interfere with DNA and RNA synthesis (be able to describe these)?

1. Nucleoside analogs: interfere with DNA and RNA synthesis. 2. Acyclovir: herpes treatment, activity, administrated orally, topically, or injected. 3. Ribavirin: Rotavirus treatment, administrates as aerosol - induces high mutation rate of RNA virus 4. Zidovudine (AZT): HIV treatment, blocks synthesis by reverse transcriptase, fairly toxic

Give some general characteristics of a virus

1. Only replicate in host cell 2. Few or no enzymes of own for metabolism - mainly use host 3. Not alive 4. has protein cells 5 Posses DNA or RNA 6. Don't have own ribosomes

How is the virus transmitted?

1. Sex, of any kind, with an infected person. 2. Shared needles or injection equipment with infected person. 3. HIV infected women to babies before or during birth and during breast feeding.

List some information about the virus life cycle (steps it takes to make more viruses.)

1. Virus attaches to CD4 receptors of cells - helper T cells (main), macrophages, dendritic cells. 2. Capsid enters cell by fusion 3. Uncoating of capsid 4. Viral RNA reverse transcribed into DNA 5. Viral DNA integrates into host chromosomal DNA. 6. DNA may produce new HIV which bud from cell (or may not produce new HIV) 7. Latent viruses in some cells.

How does attachment, penetration, maturation and release steps differ between bacteriophage and animal viruses? Which type of virus does uncoating?

Animal viruses: 1. Uses receptors on plasma membrane. 2. Endocytosis - plasma membrane folds inward to form vesicle which virus is in - loses envelope. 3. Fusion - envelope fuses w/ plasma membrane and releases capsid. 4. UNCOATING - enzymatic removal of capsid proteins. 5. Lysis - non-enveloped 6. Budding - enveloped - pushed itself out and took some of it with it. Bacteriophage: 1. Phage attaches to host cell wall. 2. Penetrates cell vial phage lysozyme and injects DNA 3. Components assembled into virions 4. Release - cell lyses (phage lysozyme) and virions released.

Describe antigenic shift and antigenic drift.

Antigenic drift: RNA virus mutates in host, becomes resistant to original virus but not "newer" viruses, slower than shift, Influenza B can only drift, happens all the time, get new strains yearly. Antigenic Shift: pigs infected with human/bird/and pig viruses, three can mix genes, completely subtype - so no resistance in population, pandemic possible, only happens occasionally.

List and give some characteristics (originated from) of the two types of the virus.

Believe it is a mutation of SIV. HIV - 1> Chimps-worldwide HIV-2 > Monkeys

What were the main substances we talked about which cause host damage?

Direct damage: Kill cells during infection, must enter into cells Produce siderophore proteins: take iron away from host iron-transport proteins, brings iron into bacterial cell. Toxins: poisonous substances produced by bacteria types: Exotoxins and Endotoxins

What is the cause of the disease? What is the main reservoir? Disease "mixing pot?"

Cause: Orthomyzovirus (RNA virus) Main reservoir: birds Mixing pot: pigs

How does a prion "work" to cause these changes in the body?

Causes large vacuoles in the brain - Spongiform encephalopathy. Can induce abnormal folding of normal cellular prion protein in the brain.

What does the prion cause to form in the body?

Causes rare neurodegenerative

What is a Coagulase?

Clots blood, prevents access to bacteria from WRC by forming a barrier, produced by Staphylococcus sp.

"We don't have any of (blank) disease (or see it) in the U.S. any more so I don't need it"

Could still be in other countries and with the ease of travel now you can be contracted with disease from traveling or people from those countries coming here and you getting sick from not being vaccinated.

Where does the DNA and RNA animal viruses biosynthesis and assembly start in the host cell?

DNA starts in the nucleus RNA starts in the cytoplasm

"Vaccines don't work"

DO your research

Know some severity of the disease information.

Each year, in the U.S., on average 36,000 people die from flu-related complications. 200,000 people are hospitalized from flu-related causes. Children (<5 years old) and adults (> 60 years old) are main targets.

What are some prevention/treatment methods used for the disease?

Education: promote abstinence, discourage promiscuity, promote condom use, no drug use. Drugs to manage symptoms (NO CURE): highly active anti-retroviral therapy, involves using a combination of drugs, RT inhibitors, protease inhibitors, fusion inhibitors. There is NO vaccine.

What are the major differences between exotoxins and endotoxins?

Exo - gm+, metabolic product, proteins unstable, high toxicity, small lethal dose. Endo - gm-, LPS when dead, lipid, stable low toxicity, high lethal dose.

What is the major endotoxin? What portion of this molecule?

Exposed to body when gm- cells die. Lipid A protein

What is the cause of AIDS?

HIV (Human Immunodeficiency Virus)

Define Pathogenicity

How microbes cause disease

What does LD50 and ID50 stand for? What is the difference between the two?

ID50: infectious dose for 50% of hosts LD50: lethal dose for 50% of hosts due to toxin potency.

What is the function of capsules?

Impairs phagocytosis, prevents desiccation, adherence

Describe toxoids

Inactivated toxins Few side effects DPT

Describe an inactivated/killed whole-microbe vaccine.

Inactivates the organism with formaldehyde or heat. Body does not have as large a response to dead/inactivated microbes. May carry other substance like LPS. Inactivated polio vaccine-injected more than once. Influenza (injection)

What is a prion and what are some characteristics?

Infectious protein Always fatal (progressive)

Describe nucleic acid vaccines

Injected gene into cells Cell makes the protein which causes the immune response. Influenza and HIV - experimental use only

What is mycolic acid and what is its function?

It is a waxy lipid found in a cell wall It is resistant to phagocytic digestion.

Describe a live attenuated vaccine.

It is a weakened live vaccine. Mutated strain used that are less virulent and no longer cause disease. Long immunity, may not need boosters. Can cause disease in the immunocompromised and a small % of the rest of the population. Oral polio vaccine - single dose MMR

"Mercury-based vaccine preservative (thimerosal) in MMR is linked to autism."

It is mercury like, but does not give you the toxic effects

What is the end result of septic shock?

Macrophages release tumor necrosis factor (TNF) > increased capillary permeability > fluid enters tissue > blood pressure drops

Why is adherence an important mechanism of pathogenicity? What molecules do microbes use for adherence?

Matchup to receptors on hosts cells - glycoproteins -lipoproteins

Explain/define/list characteristics of the mucous membrane and make suggestions as to how microorganisms use this route (examples of infections).

Mucous membrane: 1. Respiratory tract: Most frequent, easiest entry point, inhale dust/drops of moisture - cold, TB, pneumonia, measles. 2. GI Tract: Microbes are acid and bile resistant, enter in contaminated food/water - dysentery, Hep A, cholera. 3. Genitourinary tract: STI's- HIV, herpes, genital warts. 4. Conjunctiva: Eyes - conjunctivitis trachoma.

What is an interferon and how do they function?

Natural product of the immune system which stimulate cells to produce antiviral proteins.

What is an antiviral drug which is a reverse transcriptase inhibitor?

Nevirapine - HIV treatment - inactivates reverse transcriptase

"Just live healthy..."

No doubt that by being healthy you might get sick less and so on but there is still a chance you can get measles or other diseases protected with vaccines.

Define a virus

Obligate intracellular parasites

Describe the difference between the old and new taxonomic system for viruses.

Old: Base on symptoms humans had, problems - may cause more than one disease - did not work for viruses. New: nucleic acid (RNA or DNA first classification), strategy for replication, morphology

Explain/define/list characteristics of the Parenteral route and make suggestions as to how microorganisms use this route (examples of infections).

Parenteral route: Directly deposited beneath skin (puncture, injections, bites, surgery) - gangrene, dengue fever, staph infection.

What is the function of the M protein?

Part of cell surface and fimbriae - acid/heat resistant - function: assists in attachment/prevents phagocytosis by WBC - produced by Streptococcus pyogenes.

What are some antiviral drugs which are protease inhibitors? Integrase inhibitor?

Protease inhibitors - HIV treatment - Indinavir and Saquinavir. Integrase inhibitors - Raltegravir and elvitegravir.

What are invasions?

Proteins which rearrange cytoskeleton to enter a cell, produce actin baskets or cause ruffling, produced by Salmonella, Shigella, Listeria

List some characteristics and some information about the structure of the virus?

Retrovirus Genus - Lentivirus 2 identical strands of RNA Reverse transcriptase enzyme (RT) Envelope

Describe a subunit vaccine

Single antigen (Ag) or mixture of Ag: Must be administered more than once, Used when whole-agent vaccines are dangerous or cause the wrong response. Recombinant Vaccines: Other microbes are engineered to produce the desired Ag.

Explain/define/list characteristics of the skin and make suggestions as to how microorganisms use this route (examples of infections).

Skin: Impenetrable, access through hair follicles and sweat glands - ringworm, athletes foot.

First vaccine against? Was developed by?

Small pox developed by Edward Jenner

"Vaccines are not safe...have allergic reactions to them"

Some people do have an allergic reaction but not everyone, look up possible side effects for the vaccine from the CDC, look how they are made and so on.

Define herd immunity (what is the average threshold for this?)

The more people that get vaccinated the less other people get sick, the threshold varies by vaccine.

"My flu shot did not work..."

There are multiple strains of the flu and the flu shot cant protect against all the strains, unless you went to the doctor and got diagnosed with the flu strain A you cant say your vaccine didn't work.

What is a Leukocidin?

Toxin: destroys white blood cells, produced by gram+ cocci

Define a bacteriophage

Viruses that infect bacteria

What is a cytopathic effect?

Visible effects of viral infection to cells

Is there any similarity on the release step between bacteriophage and animal viruses?

Yes, because animal viruses have two ways to release and one of them is by LYSIS, which is also the only way bacteriophages can be released is by CELL LYSES.

What is a Hyaluronidase and Collagenase:

breaks down connective tissue which helps microbes spread from initial infection site, blackens tissue, produced by Clostridium perfringens (collagenase) and streptococci (hyaluronidase)

"The evil pharmaceutical companies.."

can't always blame the pharmaceutical companies for everything