HIV
One-Sentence Definition
Human immunodeficiency virus (HIV-1/HIV-2) is an enveloped lentivirus (Retroviridae) that reverse-transcribes its RNA genome into DNA, integrates into host chromosomes, and progressively depletes CD4⁺ T cells, causing AIDS if untreated.
Taxonomy & Structure
- HIV-1 (global pandemic) vs HIV-2 (West Africa, generally slower progression)
- Dimeric (+)ssRNA; reverse transcriptase (RT), integrase, protease
- Envelope gp120/gp41 (binds CD4 + CCR5/CXCR4 co-receptors)
- Groups/subtypes (HIV-1 M subtypes A–K…) matter for diagnostics and epidemiology
Replication & Pathogenesis Highlights
- Binding → fusion → RT → integration (provirus) → transcription/translation → assembly/budding
- Latent reservoirs in resting CD4 cells — barrier to cure
- Chronic immune activation; opportunistic infections and malignancies define AIDS
- Transmission: blood, sexual, perinatal
Clinical Syndromes
- Acute retroviral syndrome → chronic latency → AIDS (PJP, toxo, crypto, TB, KS, lymphoma…)
- Non-AIDS comorbidities on long-term ART (CV, bone, neuro)
Diagnosis
- Ag/Ab combo immunoassays → confirmatory differentiation; HIV RNA RT-PCR / qPCR for acute infection and infant diagnosis
- Baseline: CD4 count, HIV RNA viral load, resistance genotype before/at ART failure
- RNA Extraction for plasma viral load workflows
Treatment Notes (conceptual)
- Combination ART (typically 2–3 active agents): NRTI/NNRTI/PI/INSTI classes — INSTI-based first-line common
- Treat all; U=U (undetectable = untransmittable) when sustained suppression
- PrEP / PEP for prevention; resistance testing guides switches
- Opportunistic infection prophylaxis by CD4 thresholds
Antiviral Resistance
- RT, protease, integrase, envelope mutations — report as Stanford/IAS algorithms
- Minority variants; archived resistance in proviral DNA (research/clinical nuance)
- Links to Genotype to Phenotype Prediction and Viral Genomics and Surveillance
Genomics & Computational Notes
- Pol sequencing for resistance; whole-genome / NGS for minority variants
- Phylogenetics for transmission networks (ethical/privacy governance critical)
- Phylodynamics of regional epidemics
Related Notes
- Vaccination (no sterilizing HIV vaccine yet; pipeline active) · Infection Prevention and Control
- MOCs: MOC - Virology · MOC - Immunology · MOC - Public Health & Epidemiology · MOC - Antimicrobials
Active Recall
- Why can’t ART currently cure HIV?
- Which assay detects infection before seroconversion?
- Name three antiretroviral drug-target classes.