HIV

Question 1

what does HIV use to bind to CD4?

Answer 1

gp120 initial binding

gp41 confromational change

Question 2

what co-receptors does HIV bind to, to allow entry to the CD4+ cell?

Answer 2

CCR5

CXCR4

Question 3

which protein provides intrastructural support to HIV?

Answer 3

Gag protein

Question 4

Innate response to HIV involves:

Answer 4

non-specific activation of macrophages, NK cells, and complement
stimulation of dendritic cells via TLR
release of cytokines and chemokines

Question 5

Adaptive response: neutralising abs

Answer 5

anti-gp120, anti-gp41

Question 6

Adaptive response: non-neutralising abs

Answer 6

anti-p24

anti-Gag

Question 7

chemokines produced by CD8+ to prevent HIV entry into cells

Answer 7

RANTES

MiP a/b

Question 8

Mechanisms by which HIV damages immune response

Answer 8

1. not neutralised by abs
2. kills CD4 cells, or causes them to be killed by CTLs leading to failure of Ig/CD4 memory formation and signalling to continue immune response
3. loss of interactions with CD8, monocytes, dendritic cells, B cells
4. infected monocytes and dendritic cells are also killed so there is no means of presenting antigens, therefore no memory
5. variation and mutation

Question 9

Main test used in screening for HIV

Answer 9

ELISA ab test - looks for antibodies in the serum to HIV

Question 10

other tests for HIV - useful if screening is positive

Answer 10

1. antigen-ab tests: Western blot, looks for p24 viral capsid protein, and HIV-ab
2. being fast superseded by NAATs - looks for HIV viral RNA/DNA in the blood - can be positive 7-28 days after infection. Used in high risk pts and in pts with early sx

Question 11

How long does it take for a person to seroconvert (making HIV-abs - positive ELISA)

Answer 11

3-12 weeks, on avg 10 weeks post infection

tests not positive before this (3m)

Question 12

2 tests used in monitoring HIV

Answer 12

1) viral load - via PCR

2) CD4+ count

Question 13

Two methods of resistance testing in antiretroviral use

Answer 13

1. Phenotypic: viral replication is measured in cell cultures under increasing amounts of antiretrovirals. compared to wild type.
2. Genotypic: mutations are determined by direct sequencing, compared to wild type.

Question 14

When to start treatment in HIV

Answer 14

CD4<350

OR symptomatic

Question 15

HAART antiretroviral therapy usually consists of:

Answer 15

2 NNRTI

+ 1 PI/NRTI

Question 16

ART in pregnancy

Answer 16

Zidovudine:

• antepartum PO
• delivery IV

Question 17

ART in newborns born to HIV+ mothers

Answer 17

Zidovudine 6 weeks PO

reduces transmission from 26% to 8%

Question 18

Raltegravir, Elvitegravir

Answer 18

GRAvir = InteGRAtion inhibitors

Question 19

Ritonavir, Indinavir, Nelfinavir, Atazanavir, Amprenavir

Answer 19

NAVIR = Protease inhibitors

Question 20

Enfuvirtide

Answer 20

Fusion inhibitor

enFU

Question 21

Tenofovir, Abacavir, Trizirvir, Zidovudine, Lamivudine

Answer 21

NRTI

Question 22

Targets for NRTI/NNRTI

Answer 22

Reverse transcriptase - interrupt transcription of viral DNA

Question 23

Target for fusion inhibitors

Answer 23

gp120/gp41

Question 24

tagets for protease inhibitors

Answer 24

viral Protease - prevent release and budding of viral proteins

Question 25

Targets for integrase inhibitors

Answer 25

viral Integrase - prevent viral DNA being inserted into host DNA.