Which of the following antivirals is used primarily for treating cytomegalovirus infections?

Ganciclovir is specifically indicated for the treatment of cytomegalovirus (CMV) infections, particularly in immunocompromised individuals, such as those with HIV/AIDS or organ transplant recipients. CMV can cause serious health problems in these patients, including retinitis and other systemic infections.

Ganciclovir works as an antiviral by inhibiting viral DNA synthesis, effectively reducing the replication of the virus in infected cells. This mechanism is crucial because cytomegalovirus can lead to significant morbidity in the at-risk population it most often affects.

In contrast, Acyclovir is primarily used for herpes simplex virus and varicella-zoster virus. Sofosbuvir is an antiviral that targets hepatitis C, and Ribavirin is utilized for various viral infections, including hepatitis C and respiratory syncytial virus, but none of these are specifically effective against CMV. Therefore, Ganciclovir is the appropriate choice for treating cytomegalovirus infections.