Which drug is a protease inhibitor?

• A. Cidofovir
• B. Maraviroc
• C. Atazanavir
• D. Raltegravir

Answer: (C)

Protease inhibitors block the late step of HIV replication by inhibiting the viral protease enzyme, which is needed to process the Gag-Pol polyprotein into functional proteins. When this protease is inhibited, viral particles stay immature and noninfectious. Among the options, the drug that acts as a protease inhibitor is Atazanavir. It directly inhibits HIV-1 protease, preventing cleavage of Gag-Pol and producing noninfectious viral particles. The other choices target different stages: Cidofovir inhibits viral DNA polymerase, Maraviroc blocks the CCR5 entry receptor, and Raltegravir inhibits the integrase enzyme that integrates viral DNA into the host genome.