A method of inhibiting viral infection in a mammal in need of same, includes administering an effective amount of at least one of the compounds of FGI-103 which are represented by 273, 365 and 510 either prophylactically to prevent viral infection, or therapeutically following viral infection. These compounds appear to selectively inhibit Caspase 8 as a method of preventing infective viral particle release. They can be administered IV, IP, orally or via other conventional administration routes. The compounds are highly effective, requiring relatively low dosages on the order of 1 ng/kg-200 mg/kg of body weight.