EXAM #2: HIV I Flashcards
List four reasons that HIV is very challenging to treat and manage?
1) High genetic mutation rate
2) Evades cellular and humoral immunity
3) Evades traditional vaccine strategies
4) “Hides” in resting memory CD4+ T-cells
What is the definition of AIDS?
1) CD4+ T-cell count less than 200 OR
2) AIDS defining illness
What is the importance of the “viral load set point?”
High viral load set-point= progress to AIDS quickly
Low viral load set-point= slow progression to AIDS
What virus causes Kaposi Sarcoma?
HHV-8
At what CD4+ T-cell count to HIV+ patients get Kaposi Sarcoma?
400
At what CD4+ T-cell count to HIV+ patients get toxoplasmosis and cryptococcosis?
100
At what CD4+ T-cell count to HIV+ patients get MAC?
50
What is the difference between a single pneumococcal pneumonia diagnosis vs. recurrent pyogenic bacterial pneumonia?
Recurrent= AIDS defining Single= NOT defining, but should include HIV as part of differential
What is the current trend of HIV infections in the US?
- No real change in incidence year-to-year
- More people are living longer with HIV
What group has the highest risk of new HIV diagnosis?
Male-to-male (MSM)
*Note that in this group the incidence of HIV infection is INCREASING
What is the trend of HIV diagnoses in African Americans?
Account for roughly 1/2 of all diagnoses
*Minorities are “disproportionately affected”
What percent of the population is HIV+ but doesn’t know it?
Roughly 20%
*Note that they account for roughly half of the new HIV infections
What % of CD4+ T-cells is associated with AIDS?
AIDS= CD4+ T-cell % less than 14
What is acute retroviral syndrome?
Initial viral illness after infection with HIV
*Commonly a prolonged flu/mono like illness
What symptoms can be associated with acute retroviral syndrome aside from flu/mono sx?
- Pharyngitis, rash* or headache
- Aseptic meningitis
- Oral/ genital ulcers
*This can differentiate from EBV
In terms of HIV diagnosis, what is the first test that will be positive?
Viral RNA (week - two weeks post exposure)
What protein makes up the HIV viral capsid?
p24
How is HIV diagnosed?
1) HIV RNA PCR
2) HIV antigen (p24)/antibody testing
What is the gold standard for HIV screening?
ELISA
How is the diagnosis of HIV confirmed?
1) HIV-1 Western Blot
2) Multispot HIV-1/HIV-2 test
A reactive HIV antigen/antibody screening test is positive; multispot test for HIV-1/2 is negative. What should you do?
HIV RNA PCR
What are the current screening recommendations for HIV screening?
15 - 65 y/o as an “opt out” test i.e. you can elect not to do the test
When is repeat screening for HIV recommended?
High risk individuals (MSM)–should be tested once a year
What are the HIV screening recommendations for pregnant women?
Test all women*
*Law in IA
How does HIV-2 differ from HIV-1?
1) Less transmissable
2) Less pathogenic
3) Less likely to cause AIDS
*Coinfection is possible
What receptors/ co-receptors mediate HIV viral entry?
Receptor= CD4
Co-receptor=
- CCR5
- CXCR4
What co-receptor does the HIV that is sexually transmitted have a trophism for?
CCR5
What is a CXCR4 trophism associated with?
Faster progression to AIDS
What is the protein on the AIDS virus that binds to CCR5?
gp120
What are the benefits of a delta 32 CCR5 mutation? What is the difference between homozygous and heterozygous mutations?
Interferes with the co-receptor for HIV
- Heterozygous= slow progression to AIDS
- Homozygous= v. challenging to get infected with HIV
