The study is testing a new treatment called VIR-1388, which will be compared to a placebo (a harmless pill that does not contain any active medicine) in adults who are healthy and do not have HIV. This study is in Phase 1, which means it is one of the first stages of testing a new treatment to see if it is safe and how it affects the body. Participants will receive different doses of VIR-1388 or the placebo, and the study will happen in two parts. Part A involves people who cannot have children, and Part B includes people who can have children but must use two forms of birth control. There is an optional part of the study that could last up to three years.

• The study involves regular check-ups and safety monitoring.
• Participants should be healthy, HIV-negative, and CMV-positive.
• People with certain health conditions, or who are breastfeeding, cannot join.