Acyclovir is commonly used to treat which viral infection?

• A. Genital herpes (HSV)
• B. CMV
• C. HIV
• D. Hepatitis C

Answer: (A)

Acyclovir targets herpesviruses because its activation and action are tied to the enzymes HSV and VZV use to replicate. It’s a guanosine analog that becomes active only after viral thymidine kinase phosphorylates it to the monophosphate form; cellular kinases then convert it to the triphosphate form, which specifically inhibits the viral DNA polymerase and terminates DNA synthesis. This makes it effective for infections caused by herpesviruses, such as genital herpes, by reducing symptoms and speeding healing.

It isn’t effective for CMV because CMV lacks the viral thymidine kinase needed to activate acyclovir, so the drug isn’t efficiently activated against CMV; CMV infections are typically treated with ganciclovir. It also doesn’t work against HIV, a retrovirus, or hepatitis C, an RNA virus, which require different classes of antivirals.

So, the best choice is genital herpes caused by HSV.