HIV

Question 1

1. Discuss the origins of the AIDS epidemic.

Answer 1

Before 1930 - HIV entered human populations from chimpanzees in east central Africa

Question 2

Markers of HIV

Answer 2

CD4 lymphocyte count (main host cell for HIV and correlates with dz progression) and Plasma HIV RNA level (viral load- measure of extent of replication)

Question 3

Natural course of untreated HIV - virus load, CD4 count, immune response

Answer 3

Culturable virus in blood: spikes a month after infection, but levels drop rapidly and only start to rise again years later. CD4 count: Initial drop about a month after infection, then levels rise and stay normal until years later when viral load increases again. Immune response: Immediately increases following infection and stays elevated until T cells start dropping.

Question 4

When do HIV patients show symptoms

Answer 4

Within first month of infection, then again years later

Question 5

HIV cell entry

Answer 5

To enter a cell, HIV uses the CD4 receptor and a co-receptor, either CCR5 or CXCR4

Question 6

natural HIV immunity

Answer 6

A CCR5 mutation (naturally occuring polymorphism) causes protein truncation so CCR5 is NOT expressed on T cell surface. This confers natural immunity. White europeans and caucasians have this mutation most commonly (10-15%)

Question 7

Primary HIV infection clinical presentation

Answer 7

acute febrile illness, a mononucleosis-like illness with or without aseptic meningitis occurring 2-3 weeks after HIV exposure. Occurs in >50%. Sx can include fever, fatigue, maculopapular rash, myalgia, headache, pharyngitis, cervical nodes, arthralgia, oral ulcers, odynophagia, weight loss, diarrhea, oral candidiasis, photophobia

Question 8

List opportunistic infections in HIV/AIDS

Answer 8

Many occur only when CD4 count is low (<200): pneumocystis pneumonia, Kaposi sarcoma, thrush, CMV retinitis, CNS toxoplasmosis, abscesses,

Question 9

List the effects of antiretroviral therapy

Answer 9

Immunologic: inhibits viral replication, prevents immunologic deterioration and allows immunologic recovery. Clinical: prevents opportunistic infections, reduces hospitalizations

Question 10

Define quasispecies

Answer 10

Initial HIV viral inoculum results in a population of genetically distinct viral variants in a single infected person due to error prone nature of viral replication. The quasispecies of an individual infected person are more closely related to each other than to virus in other infected persons

Question 11

How was the Berlin patient cured of HIV?

Answer 11

HIV positive patient with leukemia was treated with chemo and two stem cell transplants. The transplanted stem cells were from a CCR5 delta 32/ CCR5 delta 32 mutated donor. At 3.5 years out he appears to be cured of HIV