Effect of dsRNA from phi 6 bacteriophage on herpetic infection in cell culture and an animal model

The double-stranded (ds) RNA from phi 6 bacteriophage inhibited herpes simplex virus type 1 (HSV-1) and HSV-2 infection in MA-104 cells but not in Vero cells. HSV-2 was more sensitive to this effect than HSV-1, with the HSV-2 ED50 being 0.25 micrograms/ml and the HSV-1 ED50 1.68 micrograms/ml. On genital infection by HSV-2 in guinea pigs, phi 6 dsRNA was more effective by intravaginal (P less than 0.05) than by intraperitoneal administration. A single dose of dsRNA of 600 micrograms/kg by intravaginal route modified favorably the natural course of the genital herpes in the treated animals (p less than 0.001). Compared with the infected controls, they showed a faster recovery with better healing of lesions; and the number and severity of recurrence was low. No mortality was observed and the control infected animals showed a mortality of 39%. Sera from dsRNA-treated animals showed antiviral activity with a 50% plaque-depressing dose (PDD50) of 10(1.5)/150 microliters; no antiviral activity was found in sera either from control infected or uninfected animals. No adverse effect was observed on the rate of growth of uninfected dsRNA-treated controls.