L6 - HIV (2)

Question 1

What are the 3 ORFs of HIV?

Answer 1

Gag
Pol
Env

Question 2

How are HIV-1 and HIV-2 different?

Answer 2

vpx instead of vpu

Question 3

Why is HIV so complex?

Answer 3

Enable replication and persistence in adult host

enabled cross-species transmission

Question 4

What happens to CD4 cells when AIDS develops?

Answer 4

CD4 and CTL count drops

Question 5

What is the half life of cells infected with HIV?

Answer 5

<2 days

10^10 virions produced per day

Question 6

What kind of latency does HIV have?

Answer 6

CLINICAL!

NOT cellular

Question 7

What is the balance shift of clinical latency?

Answer 7

more CD4 cells killed than produced

destroy lymph node

immune system weakened and overwhelmed

Question 8

What are symptoms of HIV primary infection?

Answer 8

mononucelosis-like syndrome

fever, malaise, rash, diarrhoea

Question 9

What are symptoms of clinical latency?

Answer 9

often NO symptoms

sometimes fatigue, weight loss, thrush, shingles

Question 10

What happens when CD4 cell number per ul are 200-500?

Answer 10

shingles
oral lesions 
tb
M. contagiosum
C. acuminata

Question 11

What happens when CD4 cell number per ul are LESS THAN 200?

Answer 11

protozoal - pneumocytis carinii

Bacterial - T. pallidum

Fungal - C. albicans, C neoformans

Viral - CMV, HSV EBV, KSHV

Question 12

What is ADC?

Answer 12

AIDS dementia complex

infection of brain macrophages and glial cells

Question 13

What do Th1 cells produce and what do the chemokines activate?

Answer 13

produce IL-2, IL-12, IFN-y

activate CD8+ CTLs

Question 14

What do Th2 cells produce and what do the chemokines activate?

Answer 14

IL-4, IL-10

B-lymphocytes - humoral immune system

Question 15

What cell produces Th1 and Th2 cells?

Answer 15

CD4+ T-helper cells

Question 16

What cells are atrgetted by HIV?

Answer 16

Monocytes

precursors to APCs

Macrophages

Dendritic cells

Question 17

How does HIV get into cells?

Answer 17

gp120 structure changes to bind to co-receptor chemokine

induces change in gp41

expose fusion domain

membranes fuse

Question 18

What are the 2 HIV receptors

Answer 18

CD4 - PRIMARY

Chemokine - alpha (CxC) or beta (CC)

Question 19

What part of HIV interacts with Chemokine receptor?

Answer 19

V3 loop

binds to heparan sulphate prior to binding

Question 20

What chemokine receptor is used in early HIV infection?

Answer 20

B-chemokine - CCR5

R5 viruses

NON-SYNCYTIUM INDUCING - DO NOT FUSE CELLS

Question 21

What chemokine receptor is used in later infection (AIDS)?

Answer 21

a-chemokine - CXCR4

X4 viruses

SYNCYTIUM INDUCING

Question 22

How does the receptor for HIV change?

Answer 22

mutation of V3 loop of gp120 - amino acid change allows different binding

Question 23

What cells do R5 viruses infect (HIV)?

Answer 23

Macrophage

T cells

Question 24

What cells to X4 viruses infect

Answer 24

(MEMORY) T-cells

Question 25

what is the deletion that allows HIV resistance?

Answer 25

32bp deletion in CCR5 gene

STILL hav CxCR4 genes though

Question 26

What is the role of dendritic cells in HIV infection?

Answer 26

picked up by dendritic cells

migrates to lymph node

Question 27

How can HIV associate with dendritic cells?

Answer 27

DC-SIGN

usually binds ICAM-3 on surface of T-cells

lectin domain binds to the carbohydrate on the HIV glycoprotein

Question 28

Can HIV infect dendritic cells?

Answer 28

Yes are they have CCR5 receptor in membrane

Question 29

How does HIV get from Dendritic cells to T cells?

Answer 29

virological synapse with adhesive junction

Question 30

How does a virological synapse form between T-cells?

Answer 30

requires gp:120:CD4/CCR5 interactions

clusters of receptors

avoids the immune response and damage to virus particles