6. HIV (AIDS)

Question 1

What cells do HIV infect? What does HIV cause to them?

Answer 1

CD4+ T cells (TH cells)

Induces CD4+ T cell autophagy

Question 2

Host receptors targeted by HIV?

Answer 2

CD4 receptor of T cells and chemokine coreceptor CCR5 (CXCR4)

Question 3

HIV genus?

Answer 3

Lentivirus

Question 4

HIV family?

Answer 4

Retroviridae

Question 5

HIV genome?

Answer 5

(+)ssRNA, 2 identical copies

Question 6

HIV particle contains what 4 things?

Answer 6

RT, integrase (IN), protease (PR), complex genomes (gag, pol, env polyproteins)

Question 7

What phenomenon is a severe obstacle in HIV vaccine development?

Answer 7

Error-prone viral replication

Question 8

HIV envelope glycoprotein gp120 binds to _______ on dendritic cells

Answer 8

DC-SIGN

Question 9

Synthesis of new HIV virions requires what process?

Answer 9

dsDNA intermediate integrating into host genome

Question 10

Viral dsDNA is made in the ________ using RT

Answer 10

cytoplasm

Question 11

HIV LTRs are involved in what?

Answer 11

Integration into host genome, transcriptional control

Question 12

What do gag, pol, env each encode?

Answer 12

Gag - structural proteins (MA, CA, NC)
Pol - enzymes (RT, IN, PR)
Env - envelope glycoproteins (gp160 -> gp120+gp41)

Question 13

How does HIV bind CD4+ T cells

Answer 13

HIV’s gp120 binds CD4 receptor of T cells = conformational change in gp120 => can now binds chemokine coreceptor CCR5

Question 14

What is part of the HIV viral pre-integration complex?

Answer 14

dsDNA, integrase, Vpr

Question 15

What is formed when HIV integrase causes integration of viral dsDNA genome randomly into host?

Answer 15

Provirus

Question 16

Function of Tat in HIV?

Answer 16

Enhances transcription of provirus

Question 17

Function of Rev in HIV?

Answer 17

Binds viral mRNAs and transports them to cytosol

Question 18

How does HIV exhibit temporal regulation of expression?

Answer 18

As Rev levels in nucleus increases, mRNA that gets exported to cytoplasm is less extensively-spliced = diff proteins produced (not Gag,Pol,env)

Question 19

Which part of HIV is analogous to influenza HA2?

Answer 19

gp41

Question 20

HIV RT has what 2 things?

Answer 20

• RNA-dependent DNA pol

- RNase activity (RNase H) = makes dsDNA while degrading viral template

Question 21

Signal that induces HIV conformational change?

Answer 21

Binding gp120 to CD4

Question 22

Function of HIV Vpr?

Answer 22

Transports viral dsDNA into nucleus

Question 23

Why are more higly spliced HIV mRNA produced ealry in infection and less later

Answer 23

Early there is little Rev present so mRNA remains in nucleus longer and becomes spliced. One of the spliced products codes for Rev so as more spliced products are produced, more Rev is and mRNA export gets more efficient

Question 24

Why has there been no successful HIV vaccine so far?

Answer 24

Hypervariabilit of viral proteins

• RT has no proofreading function
• RNA pol is error-prone

Ab that recognizes one gp120 may not recognize a new variant

Question 25

Main difference between HIV and polio replication? One genome similarity?

Answer 25

Both have (+)RNA genome

HIV uses a dsDNA intermediate, new viral (+)RNA is made in nucleus by host pol

Polio uses (-)RNA and everything occurs in cytoplasm, on ER-derived vesicles

Question 26

What gene encodes HIV gp160?

Answer 26

env gene, gp1260 gets spliced to gp120 + gp41

Question 27

Where is gp160 synthesized?

Answer 27

On rough ER

Question 28

The c-terminal of gp41 interacts with what?

Answer 28

Matrix protein, MA (like HA2)