Topical phosphonoacetic acid treatment of cutaneous herpes simplex infections in the guinea pig.

Phosphonoacetic acid (PAA) was evaluated as therapy for primary cutaneous herpes simplex virus (HSV) infections in guinea pigs. Epilated areas of skin were inoculated with HSV type 1 and treated in a blind fashion with topical PAA 2% cream or placebo cream, the initial application varying from 3 to 84 hours after inoculation. PAA applied 3 hours after inoculation aborts clinical infection. Even when applied 84 hours after inoculation (12 hours after the appearance of clinical lesions), PAA reduces the severity of primary HSV infection, and thus may be suitable for the treatment of human HSV infections.