HIV

Question 1

gag

Answer 1

core and matrix proteins; p24

Question 2

env

Answer 2

membrane glycoproteins: gp120 (outer) and gp41 (transmembrane)

Question 3

pol

Answer 3

Reverse transcriptase, protease, and integrase

Question 4

tat

Answer 4

Positive regulator of transcription

Question 5

rev

Answer 5

Allows export of transcripts from the nucleus

Question 6

vif

Answer 6

Affects particle infectivity

Question 7

vpr

Answer 7

Viral protein R. Transport of DNA to nucleus. Augments virion production. Cell cycle arrest.

Question 8

vpu

Answer 8

Viral protein U. Promotes intracellular degradation of CD4 and enhances release of virus from cell membrane.

Question 9

nef

Answer 9

Augments viral replication. Down-regulates CD4 and MHCH

Question 10

What is the major co-receptor for macrophage-tropic strains of HIV?

Answer 10

CCr5

Question 11

What is the major co-receptor for T cell-tropic strains of HIV?

Answer 11

CXCr4

Question 12

Most common strain of HIV in U.S.

Answer 12

HIV-1 Group M Subtype B

Question 13

Properties of Stage I HIV

Answer 13

Acute retroviral syndrome – highly contagious
30% of patients asymptomatic; others have flu-like symptoms

1. Primary infection of blood, mucosal cells
2. Infection established in lymphoid tissues
3. Acute HIV syndrome, spread throughout body
4. Immune response

Question 14

Properties of Stage II HIV

Answer 14

Clinical latency
Establishment of chronic infection; virus trapped in lymphoid tissues by follicular dendritic cells
Low-level viral replication for several years

Question 15

Properties of Stage III HIV

Answer 15

AIDS
Destruction of lymphoid tissue
Defining opportunistic illnesses

Question 16

Stage 3-Defining Opportunistic Illnesses in HIV infection

Answer 16

Kaposi sarcoma
Candidiasis
CMV
Cryptococcus
Herpes simplex
Lymphoma
Pneumonia

Question 17

Steps of HIV replication

Answer 17

1. Virus binds with CD4 on T cell surface via gp120
2. Binding induces conformational change that opens up site for co-receptor binding (CCr5: T cell / CXCr4: Macrophage)
3. HIV RNA, protease, integrase, and reverse transcriptase enter cell
4. Viral DNA is formed by reverse transcriptase in cytoplasm, then transported across nucleus via protein R, and integrated into host DNA via integrase –> now a provirus
5. New viral RNA is formed from host+viral DNA
6. New RNA transported out of nucleus via tat and and rev
7. New RNA is used to make viral proteins
8. New RNA and proteins move to cell surface and a new, immature HIV forms
9. New virus/proteins mature via protease, are exocytosed

Question 18

What is significant about CXCr4?

Answer 18

Only present on T-cells (CCr5 present on T cells and macrophages). Indicate faster/more severe illness because they provide a second method of entry into host cell.