A murine model of herpes simplex virus recrudescence.

A murine model is described in which recrudescence of herpes simplex virus (HSV) type 1 was achieved. C3H mice were shaved and irradiated with u.v. B light 3 days before being infected epidermally with a clinical isolate of HSV. Seven weeks or longer following the primary infection, the survivors were again shaved, irradiated with u.v. and mildly tape-stripped. Recrudescent lesions occurred in up to 80% of mice at the site of the original lesion in most cases, but also occasionally at other sites. Skin painting with u.v.-irradiated urocanic acid (a substance suggested to be a photomediator of the immunosuppressive effects of u.v.) in place of u.v.-irradiation induced some recrudescence but was not as efficient as u.v.-irradiation. Antibody titres to HSV had no value in predicting whether recrudescence would occur but lymphoproliferative responses in draining lymph nodes may provide some indication of viral activity at the epidermal site. A hypothesis is developed that u.v.-irradiation before primary infection with HSV induces a suppressive immune response to the virus which affects the virus-host interaction and accounts for a high incidence of recrudescent lesions on subsequent stimulus.