Immuno 8: HIV Infection

Question 1

Which cells does HIV mainly infect ?

Answer 1

CD4+ T helper cells

Question 2

Name 2 co-receptors of T cells that HIV-1 needs to bind to in order to cause infection ?

Answer 2

CCR5 or CXCR4

Question 3

List 3 routes of transmission of HIV ?

Answer 3

Sexual- especially anal sex
Infected blood- Needle sharing, transfusions, blood products
Vertical transmission- Mother to child during birth or breast feeding

Question 4

At which 2 parts of HIVs lifecycle do mutations occur that create variation in its genome ?

Answer 4

1- When reverse transcriptase converts viral RNA into DNA

2- When viral DNA is transcribed in the host’s nucleus into viral RNA

Question 5

List 4 possible mechanisms that can could cause long term non-progression in HIV infected patients ?

Answer 5

CCR5 mutation
Effective CTL & HTL response
Infection with attenuated strain of HIV
Secretion of chemokines that block HIV entry into cells - MIP-1a

Question 6

Which tests are done for HIV screening, diagnosis, severity ?

Answer 6

HIV antibodies on ELISA (screening test)
HIV antibodies on Western blot (Confirms diagnosis)
Viral RNA on PCR (viral load)
CD4+ count on flow cytometry

Question 7

Why does HAART not eliminate HIV infection ?

Answer 7

There is a reservoir of HIV in resting CD4+ cells

Question 8

List 3 classes of anti retroviral drugs and an example of a drug in each ?

Answer 8

Nucleoside reverse transcriptase inhibitors (NRTI)- Zidovudine
Nucleotide RTI- Tenofovir
Non-NRTI- efavirenz
Protease inhibitor- ritonavir