Viral Replication

Question 1

In what type of infection is virus actively produced?

Answer 1

Productive (lytic) infection

Question 2

Best known example of a latent viral infection

Answer 2

Herpes infection

Question 3

Four examples of persistent infecting viruses

Answer 3

HSV, HIV, HCV, HBV

Question 4

Viropexis

Answer 4

Receptor mediated endocytosis

Question 5

How do non-enveloped viruses enter cells?

Answer 5

Via viropexis (receptor mediated endocytosis)

Question 6

Three cellular locations where viral uncoating can occur

Answer 6

At the PM, within the endosome, or at the nuclear membrane

Question 7

Do eukaryotes make monocistronic or polycistronic mRNA and what does this mean?

Answer 7

Monocistronic (each mRNA translates to only a single protein)

Question 8

Which type has a higher mutation rate and why, DNA viruses or RNA viruses?

Answer 8

RNA viruses, because viral RNA polymerases have no proofreading capability (they are 10^-3 or 10^-4 compared to 10^-9 in DNA viruses)

Question 9

What types of proteins are involved in viral adsorption?

Answer 9

Virion attachment proteins and host receptors

Question 10

What promotes fusion of viral envelope and endosomal vesicle membrane following viropexis?

Answer 10

Acidification of the endosomal vesicle (which occurs after endocytosis) leads to a change in viral spike proteins

Question 11

How does poxvirus produce mRNA and why does it use this method?

Answer 11

Viral RNA pol produces mRNA, it doesnt use host RNA pol because it doesnt enter the nucleus

Question 12

How do (+)-strand RNA viruses create mRNA?

Answer 12

Original viral genome serves as mRNA (thus, in most cases the genomic RNA is infectious after transfection into cells)

Question 13

How do (-)-strand RNA viruses create mRNA?

Answer 13

Using viral RNA-dependent RNA pol

Question 14

Do double stranded RNA viruses need to do anything to produce mRNA or can they use part of their viral genome?

Answer 14

They do need to provide their own RNA-dependent RNA pol to make mRNA (the viral genome (+)-strand is not suitable as mRNA)

Question 15

How do retroviruses produce mRNA?

Answer 15

Viral-specific reverse transcriptase transforms viral genome RNA to (-)DNA and then also produces complementary (+)DNA strand. Host RNA pol takes over from there

Question 16

How do DNA viruses replicating in the nucleus produce monocistronic mRNA?

Answer 16

By either 1) having a promoter preceding each gene, or 2) using splicing to create monocistronic mRNAs

Question 17

How do RNA viruses create monocistronic mRNA?

Answer 17

One of the following: 1) Having a segmented genome, 2) Initiating synthesis of mRNA at beginning of a gene, or 3) Breaking down polyprotein after translation (cleavage protein resides within polyprotein itself)

Question 18

How does replication of DNA and RNA viruses differ in terms of requirements?

Answer 18

DNA viruses can use cellular enzymes for their replication (although some viruses still provide their own), while RNA viruses cannot (cells cannot replicate RNA)

Question 19

What types of viruses can undergo recombination?

Answer 19

Both DNA and RNA viruses

Question 20

What DNA viruses are capable of malignant transformation?

Answer 20

All except parvovirus