Efficacy of (E)-5-(2-bromovinyl)-2'-deoxyuridine against different herpes simplex virus strains in cell culture and against experimental herpes encephalitis in mice.

(E)-5-(2-Bromovinyl-2'-deoxyuridine (BrVUdR) showed strong antiviral activity against different laboratory strains and clinical isolates of herpes simplex virus type 1 (HSV-1) on primary rabbit testes (PRT) cells with a 50% inhibition of plaque formation (ID50) at 0.01-0.02 microM. One laboratory strain (HSV-1-S), however, was completely refractory even at concentrations as high as 100 microM. In contrast, the ID50S for all herpes simplex virus type 2 (HSV-2) strains were about 10(2) - 10(3) times higher (8-25 microM) than for the HSV-1 strains. No toxicity in mice treated with 140 mg BrVUdR/kg/day for 14 days was observed, and successful treatments of herpes encephalitis in mice induced experimentally by intracerebral infection with one laboratory strain (HSV-1-Kupka) and one clinical isolate (HSV-1-64) were achieved. Treatment of encephalitis in mice induced by the strain HSV-1-S insensitive to BrVUdR in cell culture failed to be effective. Similar antibody titers against HSV-1 were found in surviving mice of the control and of the BrVUdR-treated groups.