Recombinant human interferon-alpha A treatment of an experimental cutaneous herpes simplex virus type 1 infection of guinea pigs.

Recombinant human interferon-alpha A (rIFN-alpha A) was evaluated for therapeutic efficacy against an experimental dorsal cutaneous herpes simplex virus type 1 (HSV-1) infection of guinea pigs. Human IFN has activity in this species. Animals were treated either systemically (i.m.) or topically with different formulations of rIFN-alpha A. Therapy was initiated 24 h before (-24 h), 30 min after (+0.5 h), or 24 h following (+24 h) virus inoculation, and treatment was continued for 3-5 days. Efficacy was evaluated on day 4 following infection. Treatment with rIFN-alpha A given systemically beginning at -24 h was effective, reducing lesion number, total lesion area, and lesion virus titer by 64%, 85%, and 98% respectively (p less than 0.001). Efficacy diminished with delay in initiation of i.m. therapy. Topical rIFN-alpha A formulations were generally ineffective, showing only a marginal effect with therapy initiated -24 h or +0.5 h and no effect when treatment was delayed to +24 h. In summary, rIFN-alpha A is effective against cutaneous HSV-1 infection in this model if therapy is initiated prophylactically and if drug delivery is assured by systemic injection. Topical application of rIFN-alpha A showed little therapeutic effect. The large molecular weight of IFN likely retards its percutaneous delivery.