Valacyclovir is primarily used to treat infections caused by which viruses?

Valacyclovir is an antiviral medication primarily used to treat infections caused by herpes simplex virus (HSV) and varicella-zoster virus (HZV). It is a prodrug that is converted into acyclovir in the body, which is effective in managing conditions such as genital herpes, herpes labialis (cold sores), and shingles (herpes zoster), all of which are linked to these viruses.

Herpes simplex virus is responsible for both oral and genital herpes infections, while varicella-zoster virus is associated with chickenpox during the initial infection and can reactivate later in life to cause shingles. The effectiveness of valacyclovir against these specific viruses is attributed to its ability to inhibit viral DNA synthesis, thus reducing the severity and duration of outbreaks.

In contrast, other viruses mentioned in the options, such as HIV (human immunodeficiency virus), HCV (hepatitis C virus), RSV (respiratory syncytial virus), and CMV (cytomegalovirus), are not treated with valacyclovir. Thus, understanding that valacyclovir is specifically indicated for HSV and HZV infections clarifies why the identification of these two viruses is integral to the use of this antiviral therapy.