General virology 2 - Tesse

Question 1

what is viral replication

Answer 1

the formation of virions (extracellular or intracellular infectious form of a virus) during the infection process in the target host cells

Question 2

what is a viral factory

Answer 2

locations where the virus replicates (ie cytoplasm of mitochondria, endosomes, ER, etc)

Question 3

what is an example of a non-productive stage

Answer 3

herpesvirus latency

Question 4

Viral spread is through two methods:

Answer 4

Lymphatics
Circulation

Question 5

How can you demonstrate the viral DNA?

Answer 5

PCR

Question 6

what is the only method you can use to see the whole viral protein

Answer 6

electron microscopy

Question 7

how to see viral proteins

Answer 7

staining

Question 8

what are the six steps of viral infection and replication

Answer 8

1. viral attachment/endocytosis
2. penetration
3. uncoating
4. genome replication, mRNA production and translation
5. assembly
6. virion release

Question 9

what is the eclipse period

Answer 9

2-12 hours. Replication occurs.

Question 10

what is the latent period

Answer 10

the period between attachment until release (uncoating, replication, and maturation)

Question 11

what is tissue tropism

Answer 11

the capacity of a virus to infect cells selectively in particular organs

Question 12

what two things does tissue tropism rely on

Answer 12

susceptibility (suitable surface receptors)

Permissivity (cellular machinery must be able to support viral replication and release of new infectious particles)

Question 13

T/F: different viruses can bind the same receptor

Answer 13

true

Question 14

T/f some viruses may have more than one receptor

Answer 14

true

Question 15

how do enveloped viruses enter cells

Answer 15

1. bind receptor
2. direct membrane fusion (enveloped viruses have lipid membrane)
3. endocytosis of nucleocapsid

Question 16

t/f naked viruses can fuse directly to a cell membrane

Answer 16

false. only enveloped viruses can do this because they have a lipid membrane (naked ones do not)

Question 17

how do naked viruses enter cells

Answer 17

receptor mediated endocytosis, membrane bound vesicles, pore forming peptides that penetrate the cell membrane

Question 18

how does adenovirus enter cell

Answer 18

receptor mediated endocytosis / membrane bound vesicles

Question 19

how does picornavirus enter the cell

Answer 19

via pores from viral pore forming peptide. only the genome goes through the pore, not the whole capsid

Question 20

which step is used by all viruses

Answer 20

translation

Question 21

all DNA viruses but ___ virus go into the nucleus

Answer 21

pox

Question 22

all the RNA viruses replicate in the ___ except for the retroviruses, that go to the ___

Answer 22

cytoplasm, nucleus

Question 23

alpha mRNA from herpesvirus

Answer 23

blocks immune response, induces B mRNA production

Question 24

beta mRNA from herpesvirus

Answer 24

genome replication, induces gamma mRNA production

Question 25

GAMMA mRNA from herpesvirus

Answer 25

initiates production of structural proteins (capsid, glycoprotein)

Question 26

The retrovirus RNA is converted into DNA by

Answer 26

viral reverse transcriptase and intergrase

Question 27

retrovirus DNA integrates itself into the

Answer 27

host genome (host cell DNA)

Question 28

is a nascent virion infective

Answer 28

no. not until it’s Gag-Pol precursor protein is cleaved by viral protease

Question 29

T/F retroviruses are lifelong

Answer 29

true

Question 30

What are two main differences with the retrovirus replication cycle

Answer 30

• integrates into host DNA
• produces nascent (non-infective) virion that must be cleaved by viral proteases to become infectious

Question 31

Naked virus release causes:

Answer 31

host cell lysis

Question 32

Enveloped virus release causes:

Answer 32

budding

Question 33

influenza, rabies and paramyxoviruses exit via

Answer 33

mucosal surface of cell

Question 34

alphavirus, vesicular stomatitis virus, lentivirus exit via

Answer 34

basal surface of cell