10. Herpes (HSV)

Question 1

Genome of herpes?

Answer 1

Linear dsDNA, 2 connected segments UL and US (unique long/short)

Question 2

Herpes initially infects what?

Answer 2

Mucosal epithelial cells

Question 3

______ play an important role in regulation of herpes gene expression

Answer 3

Cellular histones

Question 4

Polymerase used? (Host/viral)

Answer 4

Virally encoded polymerase

Question 5

Example of 2 HSV tegument proteins? Functions?

Answer 5

Vhs (virion host shutoff)

Binds host mRNA and degrades it to decrease competition

VP16 - activates transcription of IE genes

Question 6

Similarity and diff between ICP0 and ICP4?

Answer 6

Both activate E and L expression

ICP0 further activates IE expression; ICP4 turns it off

Question 7

What commits HSV to the lytic cycle?

Answer 7

VP16

Question 8

Why doesn’t the virus get killed in neuronal cells?

Answer 8

No viral proteins are expressed = can’t display on MHC I to trigger killing by CTLs

Question 9

3 characteristics of herpes latency?

Answer 9

• Absent expression of viral proteins
• Cells with viral genome are not detected by host immune system
• Viral genome must persist => productive replication occur later

Question 10

What helps to silence lytic gene expression in herpes?

Answer 10

LAT (non-coding RNA)

Question 11

2 possible functions of LAT RNAs?

Answer 11

• Block CTL-mediated apoptosis

- Maintain latent state