HIV

Question 1

AIDS definition

Answer 1

CD4 count drops below 200 cells/mm3

Question 2

importance of chemokine receptors in the infectious process

Answer 2

• HIV gp120 binds to T cell CD4
• conformational change in gp120 promotes binding to chemokine receptor
• change in gp41 allows the fusion peptide to insert into the T cell membrane

Question 3

R5 viruses

Answer 3

bind to CCR5 on macrophages and memory T cells (typically early in the disease)

Question 4

R4 viruses

Answer 4

bind to CXCR4 on T cells (typically late in the disease)

Question 5

gp120

Answer 5

can bind to CD4 on nearby cells to initiate membrane fusion and pass HIV genomes to uninfected cells

Question 6

HIV transcription and replication in T cells

Answer 6

induced by TNFa and IL-2

Question 7

HIV replication in monocytes and macrophages

Answer 7

induced by IL-1, 3, 6, TNFa, IFN gamma, GM-CSF

Question 8

NFkB and SP1

Answer 8

cell activation can trigger virus production because cytokines can trigger activation of these transcription factors that bind to LTR to control viral gene transcription

Question 9

HIV replicates at a very low level early in infection

Answer 9

CD4: CD8 ratios:
Normal- 2
AIDS- 0.5

Question 10

CD4 Uninfected T cells

Answer 10

get bound by free gp120 and cant bind class II MHC proteins

Question 11

HIV Nef protein

Answer 11

downregulates expression of Class I MHC, makes infected cells invisible to CTLs

Question 12

Defective Nef gene

Answer 12

people with a defect in Nef who have HIV DO NOT progress to AIDS