HIV Flashcards
Who are considered high-risk for HIV infection?
1- Sharing needles
2- High-risk sexual behaviors (men who have sex with men, sex with multiple partners, etc.)
3- History of TB or Hepatitis infection
Signs of an Acute (early) Infection?
Non-specific flu-like symptoms
-Lasts few days to several weeks
-Patients become asymptomatic after this initial phase
When is the testing window for HIV detection?
4-12 weeks
Diagnostic Testing of HIV
Step 1: HIV antigen/antibody immunoassay
Step 2: If positive, a confirmatory test is needed to differentiate HIV-1 from HIV-2.
-HIV-1 is predominately in USA
Step 3: If confirmatory test is ‘Indeterminate’ or ‘Negative’, HIV Nucleic Acid Test is done to quantify the viral load.
Stage 1 & Stage 2 of HIV infection
Stage 1: Binding/Attachment
HIV attaches to a CD4 receptor and the CCR5 and/or CXCR4 co-receptors on the surface.
DRUGS:
-Maraviroc (CCR5 ONLY antagonist)
-Fostemsavir (Attachment inhibitor)
-Ibalizumab (Post-attachment inhibitor)
Stage 2: Fusion
The HIV viral envelope fuses with the CD4 cell membrane. HIV enters the host cell and releases HIV RNA, viral proteins and enzymes needed for replication.
DRUGS:
-Enfuvirtide (Fusion inhibitor)
Stage 3 & Stage 4 of HIV infection
Stage 3: Reverse Transcription
HIV RNA is converted to HIV DNA by reverse transcriptase. HIV DNA can then enter the CD4 cell nucleus.
DRUGS:
-NRTI: Emtricitabine, Tenofovir, Abacavir, Lamivudine, Zidovudine
-NNRTI: Efavirenz, Rilpivirine
Stage 4: Integration
Once inside of the CD4 nucleus, Integrase is released and used to insert HIV DNA into the host-cell DNA.
DRUGS:
INSTI: Bictegravir, Dolutegravir, Raltegravir, Elvitegravir
“-tegravir”
*NRTI: Nucleoside Reverse Transcriptase Inhibitor
NNRTI: Non-nucleoside reverse transcriptase inhibitor
INSTI: Integrase strand transfer inhibitors
Stage 5, Stage 6, Stage 7 of HIV Infection
Stage 5: Replication
Host cell is used to transcribe and translate HIV DNA into HIV RNA and proteins
DRUGS: None
Stage 6: Assembly
New HIV RNA, proteins and enzymes move to the cell surface and assemble into immature HIV.
DRUGS: None
Stage 7: Budding and Maturation
Immature HIV pushes out of the CD4 cell and protease creates mature HIV that can infect other cells.
DRUGS:
-PI: Atazanavir, Darunavir, etc
ending with ‘navir’
*PI: Protease Inhibitors
What important test should be done BEFORE starting Abacavir?
HLA-B*5701 allele
What important test should be done BEFORE starting Maraviroc?
Tropism Assay
Goals of ART
1- Achieve and Maintain suppression through undetectable viral load.
-Consider non-adherence or resistance if this is not achieved.
2- Restore and Preserve Immune Function through increased CD4 count
HIV ART Regimen
Backbone: 1 base + 2 NRTI
Base - Boosted PI, NNRTI or INSTI
NRTI backbone:
-TDF or TAF or Abacavir PLUS
-Emtricitabine or Lamivudine
*PI can be boosted with Ritonavir or Cobicistat
Preferred Initial ART Regimens for treatment-naive adults
One tablet daily:
1- Biktarvy (Bictegravir/Emtricitabine/TAF)
2- Triumeq (Dolutegravir/Abacavir/Lamivudine)
3- Dovato (Dolutegravir/Lamivudine)
Two tablets daily
1- Trivicay + Truvada (Dolutegravir + Emtricitabine/TDF)
2- Trivicay + Descovy (Dolutegravir + Emtricitabine/TAF)
*lamivudine and emtricitabine are interchangeable but should not be used together.
*All the above contains an integrase inhibitor with a high barrier to resistance (Bictegravir and Dolutegravir)
When should we avoid Dovato?
-HIV RNA > 500,000 copies/mL
-Known/Unknown Hepatitis B coinfection
-HIV genotyping testing is not yet available
What are the NRTIs?
- Abacavir (Ziagen)
- Emtricitabine (Emtriva)
- Lamivudine (Epivir)
- Tenofovir DF (Viread) <– greater systemic exposure compared to TAF
- Tenofovir AF
- Zidovudine (Retrovir)
MOA: Competitively inhibit the reverse transcriptase enzyme.
-Resistance develops easily in this class, that is why we need 2 in our regimen
-Zidovudine is administered IV during labor and delivery in patients with an unknown HIV RNA level or RNA > 1000 copies/mL
NRTI Issues and Features
- All NRTI: warning for lactic acidosis and hepatomegaly
-Common side effects: nausea, diarrhea
-Abacavir: test for HLA-B*5701 - contraindicated if positive
-Tenofovir (TDF>TAF): renal impairment and decreased bone mineral density
Boxed Warnings for ART drugs
1) Emtricitabine, Tenofovir, Lamivudine: Severe acute HBV liver damage if abrupt discontinuation with HBV co-infection
2) Maraviroc: Hepatotoxicity