Effect of administered interferon on rabies in rabbits

This study describes the effect of interferon on the survival of rabbits infected with a street strain of rabies virus. Interferon was prepared by collecting serum from rabbits injected with Newcastle disease virus and was characterized by biological and physicochemical methods. Rabbit serum interferon mixed and incubated with a suspension of rabies virus did not neutralize its infectivity. Rabbits were inoculated into the hind leg muscle with approximately 80 LD(50) of virus. Interferon was administered intravenously or intramuscularly, or by both methods, in the same or opposite leg as virus. Mortality due to rabies was significantly reduced by the concurrent administration of 8 x 10(5) units of interferon divided between the site of virus inoculation and intravenously. There was less protection if 3 hr elapsed between the inoculation of virus and interferon. Treatment given 24 hr after infection did not prevent death but prolonged the incubation period.