Which HIV enzyme is responsible for integrating viral DNA into the host cell genome?

Explanation

## HIV Enzyme Functions **Key Point:** Integrase is the HIV enzyme that catalyzes the insertion of reverse-transcribed viral DNA into the host cell chromosome, establishing persistent infection. ### Role of Each HIV Enzyme | Enzyme | Function | Inhibitor Class | |--------|----------|------------------| | Reverse Transcriptase | Converts viral RNA → DNA | NRTIs, NNRTIs | | **Integrase** | **Inserts DNA into host genome** | **INSTIs** | | Protease | Cleaves viral polyproteins | PIs | | Nucleocapsid protein | RNA packaging & stability | Not a drug target | **High-Yield:** Integration is essential for HIV persistence. Once integrated, the viral DNA (provirus) becomes a permanent part of the host genome and is replicated along with cellular DNA. This is why HIV cannot be cured by antiretroviral therapy alone — the integrated provirus persists in latent reservoirs. **Clinical Pearl:** Integrase strand transfer inhibitors (INSTIs: dolutegravir, bictegravir, cabotegravir) are now preferred first-line agents because they have high barrier to resistance and minimal drug interactions compared to protease inhibitors. ### Integration Process 1. Reverse transcriptase converts viral RNA to double-stranded DNA 2. Pre-integration complex enters nucleus 3. Integrase makes staggered cuts in both viral and host DNA 4. Viral DNA is inserted into host chromosome 5. Host cell DNA repair machinery fills gaps, permanently incorporating provirus [cite:Harrison 21e Ch 197]