Reinfection and reactivation of equine herpesvirus-1 in the mouse.

Balb/c mice were inoculated with equine herpesvirus-1 (EHV-1) by the intranasal (i.n.) route. Mice developed respiratory signs; virus replication occurred in the respiratory tract and viraemia was detected; some mice died. Recovered mice were given a second inoculation with the same strain 5 months later. Following the second infection no mice died, however, virus replication was again observed in the respiratory tract and viraemia was detected once more. Administration of an antiviral agent during the acute infection prevented mice from developing severe clinical signs and all survived. These mice, and some that had survived an acute infection without chemotherapy, were given a variety of stimuli, for example X-irradiation or corticosteroid injection. Reappearance of infectious virus was detected in approx. 1/3 animals in either the respiratory tract or blood. We speculate on the possible sites of latency in the model.