Micro - Virology (Viral Basics) & Prions Flashcards Preview

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Flashcards in Micro - Virology (Viral Basics) & Prions Deck (35):
1

Name, draw, and label the 3 progressions of general features for viral structure.

(1) Naked virus with icosahedral capsid - nucleic acid, capsid (2) Envelope virus with icosahedral capsid - nucleic acid, capsid, lipid bilayer, surface protein (3) Enveloped virus with helical capsid - helical capsule with nucleic acid inside, lipid bilary, surface protein; See p. 153 in First Aid for drawing and labels

2

What are 4 processes in viral genetics?

(1) Recombination (2) Reassortment (3) Complementation (4) Phenotypic mixing

3

What is recombination?

Exchange of gene between 2 chromosomes by crossing over within regions of significant base sequence homology

4

What is reassortment? What virus and consequences should you associate with this process?

When viruses with segmented genomes (e.g., influenza virus) exchange segments; High-frequency recombination. Cause of worldwide influenza pandemics

5

What is complementation?

When 1 or 2 viruses that infect the cell has a mutation that results in a nonfunctional protein. The nonmutated virus "complements" the mutated one by making a functional protein that serves both viruses

6

What is phenotypic mixing?

Occurs with simultaneous infection of a cell with 2 viruses. Genome of virus A can be partially or completely coated (forming pseudovirion) with surface proteins of virus B. Type B protein coat determines the tropism (infectivity) of the hybrid virus. However, the progeny from this infection have a type A coat that is encoded by its type A genetic material.

7

What are the different kinds of viral vaccines?

(1) Live attenuated (2) Killed (3) Recombinant

8

What kind of immunity do live attenuated vaccines induce? What is a potential side effect?

Induce humoral and cell-mediated immunity, but have reverted to virulence on rare occasions

9

Contrast live attenuated and killed/inactivated vaccines in terms of immunity induced and risks posed.

LIVE ATTENUATED - Induce humoral and cell-mediated immunity, but have reverted to virulence on rare occasions; KILLED/INACTIVATED - Induce only humoral immunity but are stable

10

What are examples of live attenuated vaccines?

(1) Smallpox (2) Yellow fever (3) Chickenpox (VZV) (4) Sabin's polio virus (5) MMR (6) Influenza (intransal); LIVE attenuated - SMALLpox, YELLOW fever, CHICKENpox (vzv), SABIN'S polio virus, MMR, Influenza (IntraNasal) = Think: "LIVE! one night only! see SMALL YELLOW CHICKENS get vaccinated with SABIN's and MMR! It's INcredible!"

11

What are examples of killed vaccines?

(1) Rabies (2) Influenza (injected) (3) Salk Polio (4) HAV vaccines; Think: "RIP Always, salK = Killer"

12

What are examples of recombinant vaccines? Give specifics on antigens/types as they apply.

(1) HBV (antigen = recombinant HBsAg) (2) HPV (types 6, 11, 16, and 18)

13

What is a live attenuated vaccine that can be given to HIV-positive patients, and in what context?

MMR = measles, mumps, rubella (live attenuated vaccine that can be given to HIV-positive patients) who do not show signs of immunodeficiency)

14

What are 2 advantages of live attenuated vaccines? In what patient population(s) is it dangerous to give live vaccines?

(1) No booster needed for live attenuated vaccines (2) Cellular and humoral immunity (unlike only humoral in Killed vaccines); Immunocompromised patients & their close contacts

15

What kind of nucleic acid material do nearly all DNA viruses have? What is the exception, and what is its nucleic acid material?

dsDNA, except Parvoviridae = ssDNA; Think: "Parvus = small" and "all are dsDNA (like our cells), except 'part-of-a-virus' (parvovirus is ssDNA"

16

What is the shape/form of nucleic acid material in nearly all nearly DNA viruses? What are the exceptions, and what is their shape/form of nucleic acid material?

Linear, except papilloma-, polyoma-, and hepadnaviruses = circular

17

What kind of nucleic acid material do nearly all RNA viruses have? What is the exception, and what is its nucleic acid material?

ssRNA, except Revoiridae = dsRNA; all are ssRna (like our rna), except (REOvirus) = dsRNA; Think: "REpeatO-virus"

18

What are the positive-stranded RNA viruses?

(1) Retrovirus (2) Togavirus (3) Flavivirus (4) Coronavirus (5) Hepevirus (6) Calcivirus (7) Picornavirus; Think: "i went to a RETRO TOGA party where i drank FLAVored CORONA and ate HIPPY CALIfornia PICkles."

19

Which purified nucleic acids are infectious?

INFECTIOUS: Purified nucleic acids of most dsDNA (except poxviruses and HBV) and (+) strand ssRNA (like mRNA) viruses

20

Which naked nucleic acids are not infectious, and why?

NON-INFECTIOUS: Naked nucleic acids of (-) strand ssRNA and dsRNA viruses, because they require polymerases contained in complete virion

21

Where do nearly all DNA viruses replicate? What is the exception?

All replicate in the nucleus (except poxvirus)

22

Where do nearly all RNA viruses replicate? What are the exceptions?

All replicate in the cytoplasm (except influenza virus and retroviruses)

23

What are naked viruses? What are examples of naked viruses?

Nonenveloped viruses; (1) Papillomavirus (2) Adenovirus (3) Picornavirus (4) Polyomavirus (5) Calcivirus (6) Parvovirus (7) Reovirus (8) Hepevirus; Think: "give PAPP smears and CPR to a NAKED HEPpy (hippy), DNA = PAPP, RNA = CPR, & hepevirus"

24

How do enveloped viruses generally acquire their envelopes? What is the exception to this, and how does it acquire its envelope?

Generally, enveloped viruses acquire their envelopes from plasma membrane when they exit from cell; Exceptions include herpesviruses, which acquire envelops from nuclear membrane

25

What are the 5 general rules of DNA viruses, and their exceptions?

(1) are HHAPPPy viruses (Hepadna, Herpes, Adeno, Pox, Parvo, Papilloma, Polyoma) (2) are double stranded (except Parvo = single stranded) (3) are linear (except Papilloma & Polyoma = circular, supercoiled & Hepadna = circular, incomplete) (4) are icosahedral (except pox = complex) (5) replicate in the nucleus (except pox = carries own DNA-dependent RNA polymerase)

26

What are the DNA viruses?

Hepadna, Herpes, Adeno, Pox, Parvo, Papilloma, Polyoma; Think: "DNA viruses are HHAPPPy viruses"

27

Are nearly all DNA viruses double stranded or single stranded? What is the exception to this general rule?

Double stranded; Except Parvo = single stranded

28

What shape/form is the nucleic material in nearly all DNA viruses? What are the exceptions to this general rule?

Linear; Except Papilloma & Polyoma (circular, supercoiled) & Hepadna (circular, incomplete)

29

What shape of caspid do nearly all DNA viruses have? What is the exception?

Icosahedral; Except pox = complex

30

Where do nearly all DNA viruses replicate? What is the exception?

Replicate in the nucleus; Except pox (carries own DNA-dependent RNA polymerase)

31

What causes prion diseases?

Prion diseases are caused by the conversion of a normal cellular protein termed prion protein (PrP^c) to a Beta-pleated form (PrP^sc), which is transmissible

32

Again, what causes prion disease? Is it transmissible?

Prion diseases are caused by the conversion of a normal cellular protein termed prion protein (PrP^c) to a Beta-pleated form (PrP^sc), which is transmissible

33

What role does PrP^sc directly play in prion disease?

PrP^SC resists degradation and facilitates the conversion of still more PrP^c to PrP^sc

34

What conditions result from the accumulation of PrP^sc?

Accumulation of PrP^sc results in spongiform encephalopathy and dementia, ataxia, and death

35

What are the different forms of prion disease? Give an example of each form.

It can be (1) Sporadic (Creutzfeldt-Jakob disease -- rapidly progressive dementia), (2) Inherited (Gerstmann-Straussler-Scheinker syndrome), or (3) Acquired (kuru)

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