Viral

Question 1

Strategies for immune evasion by viruses

Answer 1

• Ag variation
• latency
• resistance to/exploitation of immune effector mechanisms

Question 2

Examples of Viral subversion of MHC class I processing

Answer 2

EBNA-1
- hard to digest with proteasome

hCMV US6
- inhibit TAP activity

HIV-1 Vpu
- destabilizes new MHC class I molecules

hCMV US3
- slows export of MHC class I

HIV-1 Nef
- increases internalization of MHC I

Question 3

Why no example of a proteasome inhibitor?

Answer 3

• involved in destruction of poorly folded proteins

- interference generally results in decreased viral infectivity

Question 4

Differences between RMA and RMA/s cel lines

Answer 4

RMA

• high MHC class I
• more malignant
• less easily rejected
• memory generated
• T cells

RMA/s

• low MHC class I
• less malignant
• more easily rejected
• no memory generated
• NK cells

Question 5

MHC class I-like viral products

Answer 5

• mCMV m157 (binds inhibitory class I specific receptor)
• hCMV UL142 (inhibits NK clones)
• hCMV UL18 (inhibits NK cells expressing its inhibitory ligand)

Question 6

Why do some NK cells have activating Class I specific receptors

Answer 6

• if host has activating receptor and MHC class I ligand, IS must silence all NK cells expressing activating receptor
• so viruses create MHC class I-like molecules