05a: Virus Intro

Question 1

Only (X) virus is truly latent, while other can be “clinically” latent. What’s the difference.

Answer 1

X = herpes
NOT replicating (just hangs in cells); clinically latent virus still replicates

Question 2

Viruses can only make (E/macromolecules) independentl. Thus, they replicate (intra/extra)-cellularly.

Answer 2

Neither!

Obligate intracellular parasites

Question 3

T/F: Viruses can contain both DNA and RNA simultaneously.

Answer 3

False - only one or the other

Question 4

Viral nucleic acid genome is surrounded by (X), which in (some/all) cases can also be surrounded by (Y).

Answer 4

X = capsid
Some;
Y = envelope

Question 5

Viral envelopes are composed of (X) proteins and (Y) lipids.

Answer 5

X = viral glycoproteins
Y = host cell lipids

Question 6

(Enveloped/non-enveloped) viruses are more susceptible to inactivation by detergents, acid, heat, etc. Thus, they’re usually not transmitted via (X) routes.

Answer 6

Enveloped;

X = fecal/oral

Question 7

How might an enveloped virus be transmitted?

Answer 7

1. Droplets/secretions

2. Sex or blood contact

Question 8

(Enveloped/non-enveloped) viruses are tough and generally transmitted by which routes?

Answer 8

Non-enveloped;

Fomites, small droplets, fecal-oral route

Question 9

A complete virus particle is called:

Answer 9

Virion

Question 10

Enveloped viruses generally released from cell via (X). And non-enveloped via (Y).

Answer 10

X = budding
Y = lysis

Question 11

Viruses are mainly classified based on:

Answer 11

1. Nucleic Acid

2. Capsid

Question 12

List the DNA Viruses you have to know.

Answer 12

Acronym: HHAPPPPy

1. Herpes
2. Hepadna
3. Adeno
4. Papilloma
5. Parvo
6. Pox
7. Polyoma

Question 13

Most DNA viruses have (ss/ds) genome, (X) symmetry, and replicate in (nucleus/cytoplasm).

Answer 13

dsDNA;
X = icosahedral
Nucleus

Question 14

Which DNA virus, unlike most, has (ss/ds) genome?

Answer 14

ssDNA;

Parvoviridae

Question 15

Which DNA virus, unlike most, has complex symmetry?

Answer 15

Poxviridae

Question 16

Which DNA virus, unlike most, replicates in (nucleus/cytoplasm).

Answer 16

Cytoplasm;

Poxviridae

Question 17

List three DNA viruses that are enveloped.

Answer 17

1. Herpes
2. Hepadna
3. Pox

Question 18

List three DNA viruses that are naked.

Answer 18

1. Adeno
2. Papilloma
3. Parvo

Question 19

Most RNA viruses are (ss/ds), have (X) capsid symmetry, and replicate in (nucleus/cytoplasm).

Answer 19

ssRNA;
X = helical
Cytoplasm

Question 20

Of the ssRNA viruses, (X)% are (-) stranded and (Y)% are (+) stranded.

Answer 20

X = Y = 50

Question 21

T/F: No molecules or drugs can permeate the viral capsid.

Answer 21

False - large molecules (nucleases) cannot, but small molecules (NT) and some anti-viral drugs can

Question 22

Viral capsid is assembled from one or small number of repeating (X) structural units. These can be visualized via (Y) microscopy.

Answer 22

X = capsomers
Y = electron

Question 23

T/F: Although viral envelope is asymmetric, the viral capsid always exhibits icosahedral or helical symmetry.

Answer 23

False - some capsids are complex/asymmetrical (POX VIRUS)

Question 24

T/F: All viruses use host cell ribosomes for protein synthesis

Answer 24

True

Question 25

(X) polymerases are not found in our host cells and can be good targets for antiviral therapy.

Answer 25

X = RNA-dependent DNA pol (reverse transcriptase) and RNA-dependent RNA pol

Question 26

The (+/-) sense RNA genome can be recognized by host ribosomes and translated into protein.

Answer 26

(+) sense

Question 27

(X) viruses must carry their own RNA-dependent-RNA Pol. Why?

Answer 27

X = ALL RNA VIRUSES!

(-) RNA virus: to make (+) strand that host ribosomes recognize
(+) RNA virus: to make (-) strands that serve as template for more (+) strand synthesis

Question 28

Early phase of viral replication. What’s happening?

Answer 28

1. Target cell recognition, attachment, and penetration

2. Disassembly/uncoating of viral genome and trafficking to appropriate site

Question 29

Following the early phase of viral replication, (X) phase is characterized by (lower/higher) viral conc. in body. What occurs in this phase?

Answer 29

X = eclipse
Lower;

Virions can’t be detected (due to disassembly); replication is taking place

Question 30

A “productive” viral infection means that (X) occurs. Whether or not the infection is productive depends on (host/virus).

Answer 30

X = infectious progeny virions are produced

Both; must have permissive host cell and a non-defective virus

Question 31

A defective virus infects host cell and fails to produce infectious progeny. This is referred to as a(n) (X) infection.

Answer 31

X = abortive

Question 32

Naked viruses enter host by which two mechanisms?

Answer 32

1. Receptor-mediated endocytosis (taken up into endosomes)

2. Viropexis (virion penetrates PM directly)

Question 33

A(n) (X) mutation results in less virulent strains or variants of virus.

Answer 33

X = attenuated

Question 34

(X) refers to phenomenon where co-infection of 2 viruses allows replication of 1 or both under normally non-permissive conditions. This can’t occur if viruses are:

Answer 34

X = complementation

Defective in the same gene (since one virus will provide gene product that’s defective in the other virus)