In a patient who has developed resistance to zidovudine (AZT) during HIV treatment, which protein's gene is most likely mutated?

The correct answer pertains to the polymerase, specifically reverse transcriptase, which is encoded by the pol gene in HIV. Zidovudine (AZT) is a nucleoside reverse transcriptase inhibitor (NRTI) that targets the reverse transcriptase enzyme responsible for converting viral RNA into DNA.

When HIV develops resistance to zidovudine, mutations typically occur in the gene encoding the reverse transcriptase. These mutations can decrease the drug's efficacy by altering the enzyme's binding site or overall function, allowing the virus to replicate even in the presence of the drug.

Focusing on the other options, the envelope glycoproteins are responsible for virus entry into host cells and are not primarily involved in the mechanism of action of zidovudine. Integrase mutations relate to integrase inhibitors, affecting how the virus integrates its genetic material into the host genome, which is not the target of zidovudine. Protease is another enzyme crucial for HIV maturation but is targeted by a different class of antiretroviral medications known as protease inhibitors.

Therefore, resistance to zidovudine is most directly associated with mutations in the polymerase gene, leading to the enzyme's altered characteristics that enable continued viral replication despite the presence