The local suppression of the immune response is systemically compensated. BALB/cJ mice were treated with PPVO or placebo. After 16 h, anti-CD95L antibodies were administered and the mice were infected with a lethal dose of herpesvirus. Eighty percent of the placebo-pretreated mice died after 12 days. In contrast, PPVO pretreatment led to significantly prolonged survival (n = 10; P < 0.05), indicating a systemic stimulatory effect that occurs about 1 day after PPVO exposure. Blocking the CD95/CD95L pathway of apoptosis did modulate the course of herpes and led to a higher survival rate in these mice (not statistically significant). However, when pretreated with PPVO, 80% of the animals survived (P < 0.05).