Zidovudine targets which HIV enzyme?

• A. Reverse transcriptase
• B. Integrase
• C. Protease
• D. Helicase

Answer: (A)

Zidovudine is a thymidine analog used as a nucleoside reverse transcriptase inhibitor. It is phosphorylated inside cells to zidovudine triphosphate, which competes with natural thymidine triphosphate for incorporation by HIV reverse transcriptase during viral DNA synthesis. Once incorporated, it lacks a 3' hydroxyl group, so the viral DNA chain cannot be extended, effectively terminating DNA synthesis. By blocking reverse transcription, Zidovudine prevents HIV from converting its RNA genome into DNA, a crucial step in replication. The other enzymes listed have different roles—integrase inserts viral DNA into the host genome, protease processes viral proteins, and helicase unwinds nucleic acids—not targeted by Zidovudine.