Treatment of murine cytomegalovirus pneumonia with acyclovir and interferon.

A murine model of lethal cytomegalovirus pneumonia following intratracheal inoculation of normal mice was used to study the effects of antiviral therapy with acyclovir (ACV) and interferon (IF), alone and in combination. Five hundred units of fibroblast IF administered intraperitoneally the day prior to infection and 100 mg/kg/day ACV administered intraperitoneally for 7 days beginning within 3 h of infection were both highly effective in preventing mortality. Compared to the condition of untreated animals, each drug reduced viral titers in lung homogenates of the treated animals 7 days after infection. However ACV, unlike IF, diminished viral growth in the lung at 14 days, prevented viral dissemination to spleens and salivary glands in some animals, and significantly protected animals from reactivation of virus during immunosuppression 2 months after infection. The combination of ACV + IF offered no increased antiviral activity compared to ACV alone and failed to protect animals from reactivation. In these experiments the overall antiviral activity of ACV alone was greater than IF and the combination of ACV + IF.