HIV Flashcards
How does HIV damage the immune system
- Binds via gp120 envelope glycoprotein
- To CD4 receptors on cells
- CD4+ve cells move to lymphoid tissue, where the virus replicates
- Impaired function of infected CD4+ve cells reduces immune function
What cells are CD4+ve
- T lymphocytes
- Monocytes
- Macrophages
- Neural cells
What predicts the progression of HIV to AIDS
Viral load (number of circulating viruses)
Stages of HIV infection
- Seroconversion (primary infection)
- Asymptomatic infection
- Aids-related complex (ARC)
Time scales of the stages of HIV to AIDS
HIV>AIDS = ~8yrs
ARC>AIDS = ~2yrs
AIDS>Death = ~2yrs
(Without HAART)
3 signs that best correlate to AIDS progression
- Chronic fever
- PGL (persistent generalised lymphadenopathy)
- Cough >1mth
Describe the seroconversion stage
- May be accompanied by transient illness for 2-6wks after exposure
- Fever + malaise + myalgia
- Pharyngitis
- Maculopapular rash
Define persistent generalised lymphadenopathy
- > 1cm diameter
- 2/> extra-inguinal sites
- 3/> months
What are the constitutional symptoms of HIV and what are the referred to as
AIDS-related complex (ARC)
- Temperature
- Night sweats
- Diarrhoea
- Weight loss
- +/- minor opportunistic infections (oral candida)
How to diagnose HIV
- Serum/salivary HIV-ab by ELISA
- Serum p24 antigen level
What is the limitation of serum/salivary HIV-ab
Takes ~1-3wks post exposure to be +ve (so can miss early exposures)
What is given in PEP for HIV
-Tenofovir + Emtricitabine (Truvada)
AND
-Lopinavir + Ritonavir (Kaletra)
Early signs of acute seroconversion
- Lymphadenopathy + rash
- Headache + (rarely) meningitis
What other condition can HIV cause
- Osteoporosis
- Dementia
What part of HIV are HAART thought to be useless in
Dementia, “brain is a sanctuary for HIV”
What is the aim of HAART
- Reduce viral load
- Restore immune function
What can be given alongside HAART to reduce frequency of resting cell infection
Valproic acid
How to monitor a HIV infection
- CD4 T cell count + HIV RNA + U&E, FBC, creatinine, bilirubin/LFTs (every 3-6months)
- Fasting lipid profile + glucose (annually)
Indications for initiating HAART
- Hx of AIDS defining illness or CD4 count <350 cells/microL
- Pregnant or HIV associated nephropathy
- High viral load or CD4 count falling rapidly (still above 350)
How many different drugs should be used during HAART
3/>
When to suspect poor adherence
If viral load rebounds
When should you change to a new combination of HAARTs
- When viral load remains high, despite good adherence
- Consistent fall in CD4 count
When should there be undetectable viral loads
4 months after starting HAART
Example of a HAART regimen
-Efavirenz and Lamivudine + Tenofovir
3 types of anti-retrovirals used in HART
- Protease inhibitors
- Nucleoside reverse transcriptase inhibitors (NRTI)
- Non-nucleoside reverse transcriptase inhibitors (NNRTI)
2 examples of NRTI
Lamivudine + Tenofovir
Example of Protease inhibitor
Ritonavir
Example of NNRTI
-Efavirenz
2 examples of a once-a-day tablet
Atripla + Stribild
