7 retroviruses B

Question 1

what drugs are used in the HAART” (highly active anti-retroviral therapy) ?

Answer 1

3 drugs in all

2 RT + protease inhibitor

Question 2

what are the 2 regulatory proteins for HIV?

Answer 2

Tat - transactivator of transcription -

Rev - regulator of virion expression - allows the transport of unspliced RNA from nuclease to cytoplasm

Question 3

what are the 2

Restriction Factors of HIV?

Answer 3

viral proteins that overcome cellular defenses, or ‘restrictions’!

Vif – virion infectivity factor

Vpu - allows release of virus

Question 4

what does HIV Vif do?

Answer 4

causes a cells antiviral protein to be degreaded.

if the protein was not degraded by Vif then it would go with the virons into the new cell and block RT by making lots of mutations.

Question 5

what does HIV vpu do?

Answer 5

promotes the virion release from the cell

inhibits tetherin which would useally cause the virius to be tethered to the cell and not fully released.

Question 6

what picture has tetherin and is infected by HIV?

waht picture has HIV with a deleted VPU?

Answer 6

the top 3 have some factor that stops the tetherin from working

the botttom one has a HIV infection with a deletion of VPU. so teetherin still works.

Question 7

for HIV infection what is required but not sufficent for the infection?

Answer 7

CD4 is the intial receptor

you also need a co receptor for the receptor to take hold.

Question 8

HIV

what is M tropic?

Answer 8

wont affect T cell line in laboratory

will affect macrophages

Question 9

HIV

what is the M-tropic also called?

what is the co receptor?

Answer 9

aka r5-tropic

they affect the CCR5 receptor

Question 10

what tropic strain is of more concern?

why?

Answer 10

the M-tropic is more concerining

CCR5 coreceptor

it is the virus that causes person to person transmission.

Question 11

what is T tropic HIV aka?

what is the coreceptor associated with it?

Answer 11

X4 - tropic

it is CXCR4

it is a late emerging strain.

Question 12

what is the importance of co-receptors in terms of some people being HIV resistance?

Answer 12

some pepole have a

(∆32) homozygous deletion that causes their CCR5 receptors to be deleted.

if they are heterozygous they still get infected but it happens alot slower.

Question 13

after the CD4 binds to the viris what part of the receptor has the fusion domains?

what happens after they bind?

Answer 13

the gp40

has the fusion peptides and

they are exposed after the gp 40 binds.

the fusion peptides bind then the coreceptor helps with the total fusion.

Question 14

what drug blocks the snapback of the gp41 stopping the fusion process?

Answer 14

t-20

Question 15

what are the 3 diffrent disease mechanisms of HIV?

Answer 15

they can directly kill the CD4 Tcells (massive virus production causes membrane leakage)

indirect effects

immune response kills the infected T cells.

impair the immune system

loss of Tcell cuases the immune system to severly compromised.

Question 16

what is the course of an HIV infection?

Answer 16

ACute stage:

virsis increases alot and then gets killed off by the CTL

the virus lays in the lyphm node and in the GALT and increases alot

asymptomatic phase:

strong immune response but the CD4 is slowly decreasing.

Sypmtomatic AIDS stage

CD4 depleted

susceptible to many opportunistic infections.

Question 17

what tests can be done for HIV infeciton?

Answer 17

Serology (cannot detect newly infected, unreliable until 4-6 wk post-infection!

! !- Ab ELISA: initial screening, detect Ab to virus!

! !! !- Rapid oral test: inexpensive, fast results!

! !- Ag ELISA: detect p24 (capsid) antigen earlier than Ab !

! !- Western blot: confirmation test, uses patient Ab to detect HIV protein! !

RNA RT-PCR: detects virus in blood!
!
Real-time RT-PCR: quantitate virus in blood!

• very sensitive (≤ 50 HIV RNA copies per ml), detect virus before ! ! !seroconversion (high risk groups, new borns)!
• gauges viral load in asymptomatic patients with low titers (important for
  prognosis) ! !!

Question 18

when is a ELISA test valuable?

Answer 18

only works 4-6 weeks post infection

cannot detect newly infected.

Question 19

what are the different types of drugs available for HIV treatemnt?

Answer 19

!1. RT inhibitor: Nucleoside/nonnucleoside analogs (AZT etc. >16 drugs). !

! !Effective but drug resistant strains rapidly appear. !
! ! !(billion viruses produced per day! RT error prone, 5 errors/genome)!

!

!2. Protease inhibitors (>11 drugs): extremely effective, reduce viral load by!

! ! 30-100X alone, but still problem of drug resistant strains.! !

!3. Fusion inhibitor (T-20) available but expensive, must be injected.! !

!4.! Entry Inhibitors (Maraviroc) - CCR5 co-receptor antagonist. Aug, 2007.!

!5. Integrase inhibitor (Raltegravir): Oct, 2007. (cost: $9,855/year). !

Question 20

where does the HIV last even when on HAART for longer than 5 years?

Answer 20

it lasts in the Memory T cells.