Student Memory Support
Topic 23 — HIV, Herpesvirus Infections and Antiviral Pharmacotherapy
3rd Year MBBS • Infection and Inflammation • High-yield memory reinforcement and last-minute revision
1. High-Yield Flashcards
Tap each question to reveal the answer.
Which HIV glycoprotein binds to CD4 and co-receptors during viral attachment?
gp120.
Which HIV glycoprotein mediates fusion with the host-cell membrane?
gp41.
Which three HIV enzymes are major antiretroviral targets?
Reverse transcriptase, integrase and protease.
What is the main immunological abnormality responsible for opportunistic infections in HIV?
Progressive loss and dysfunction of CD4-positive T lymphocytes.
Which HIV laboratory marker reflects active viral replication?
Plasma HIV RNA level, or viral load.
Which HIV laboratory measurement reflects the degree of immune impairment?
CD4 T-cell count.
What important biological property explains recurrent herpesvirus infections?
Lifelong latency with possible later reactivation.
What disease results from primary varicella-zoster virus infection?
Chickenpox.
What disease results from reactivation of latent varicella-zoster virus?
Herpes zoster.
Which enzyme performs the first activation step of acyclovir in infected cells?
Viral thymidine kinase.
What is the major antiviral mechanism of activated acyclovir?
Inhibition of viral DNA polymerase with termination of viral DNA-chain elongation.
What important toxicity is associated with intravenous acyclovir?
Renal toxicity due to crystal precipitation in renal tubules.
Which antiviral drug has an important role in CMV retinitis?
Ganciclovir.
What major adverse effect limits ganciclovir therapy?
Bone-marrow suppression, especially neutropenia.
Which adverse effect is classically associated with zidovudine?
Bone-marrow suppression, particularly anemia and neutropenia.
Which adverse effect is classically associated with indinavir?
Nephrolithiasis.
2. Mnemonics
Mnemonic Title: Major Anti-HIV Drug Classes
ENIP
Meaning: Entry inhibitors, NRTIs/NNRTIs, Integrase inhibitors, Protease inhibitors.
Mnemonic Title: HIV Enzyme Sequence
RIP
Meaning: Reverse transcriptase makes viral DNA → Integrase inserts it into host DNA → Protease matures viral particles.
Mnemonic Title: Two Classic Drug Toxicities
ZI
Meaning: Zidovudine → bone-marrow suppression; Indinavir → renal stones.
3. Memory Tables
HIV Drug Classes and Targets
| Class | Main Target | Memory Effect |
|---|---|---|
| Entry inhibitors | Attachment/co-receptor/fusion | Stop viral entry |
| NRTIs | Reverse transcriptase | Abnormal substrate; stops DNA elongation |
| NNRTIs | Reverse transcriptase | Direct enzyme inhibition |
| Integrase inhibitors | Integrase | Prevent host-genome insertion |
| Protease inhibitors | Protease | Prevent viral maturation |
Acyclovir vs Ganciclovir
| Feature | Acyclovir | Ganciclovir |
|---|---|---|
| Main use | HSV and VZV infections | CMV, especially CMV retinitis |
| Target | Viral DNA polymerase | Viral DNA synthesis |
| Key toxicity | Nephrotoxicity | Bone-marrow suppression |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- gp120 attaches HIV to CD4/co-receptor; gp41 mediates fusion.
- HIV reverse transcriptase converts viral RNA information into DNA.
- Integrase inserts viral DNA into the host genome.
- Protease is required for maturation of infectious HIV particles.
- CD4 count reflects immune impairment; plasma HIV RNA reflects viral replication.
- Herpesviruses are enveloped DNA viruses characterized by latency and reactivation.
- Chickenpox is primary VZV infection; herpes zoster is reactivation.
- Acyclovir inhibits viral DNA polymerase after activation in infected cells.
- Acyclovir is mainly eliminated by the kidneys; accumulation increases toxicity risk.
- Ganciclovir is important in CMV retinitis and may suppress bone marrow.
- Combination antiretroviral therapy suppresses HIV at multiple targets and reduces resistance.
- HIV care requires confidentiality, informed consent and non-discrimination.
KMU Exam Trap:
Do not confuse CD4 count with viral load: CD4 reflects immune status, while HIV RNA reflects active viral replication.
Do not confuse CD4 count with viral load: CD4 reflects immune status, while HIV RNA reflects active viral replication.
5. Clinical Memory Hooks
Progressive recurrent opportunistic infections in HIV
→ progressive CD4-cell loss and impaired cell-mediated immunity
→ progressive CD4-cell loss and impaired cell-mediated immunity
Childhood chickenpox followed years later by a painful dermatomal eruption
→ latent VZV has reactivated as herpes zoster
→ latent VZV has reactivated as herpes zoster
Rise in creatinine during intravenous acyclovir therapy
→ renal elimination and crystal-associated nephrotoxicity
→ renal elimination and crystal-associated nephrotoxicity
Visual blurring in an immunocompromised patient with CMV retinitis
→ ganciclovir is an important anti-CMV drug
→ ganciclovir is an important anti-CMV drug
HIV-positive patient whose relative requests confidential test information
→ protect confidentiality unless justified professional or legal disclosure applies
→ protect confidentiality unless justified professional or legal disclosure applies
6. Starred High-Yield Exam Points
- ⭐ gp120 mediates HIV attachment, while gp41 mediates membrane fusion.
- ⭐ Progressive CD4 T-cell loss is the major basis of HIV-associated opportunistic disease.
- ⭐ Reverse transcriptase → viral DNA; integrase → genome insertion; protease → maturation.
- ⭐ Acyclovir requires viral thymidine kinase for initial activation and then inhibits viral DNA polymerase.
- ⭐ Ganciclovir is important for CMV retinitis but may cause severe bone-marrow suppression.
- ⭐ Zidovudine → anemia/neutropenia; indinavir → nephrolithiasis.
- ⭐ HAART uses multiple antiviral targets to achieve stronger suppression and reduce resistance.
- ⭐ HIV status is confidential medical information; consent and non-discrimination remain key medico-legal principles.