Rabies in Rabbits and Mice: Protective Effect of Polyriboinosinic-Polyribocytidylic Acid

The protective effect of the interferon inducer, polyriboinosinic-polyribocytidylic acid (poly I:C), was studied in rabbits and mice experimentally infected with street and fixed strains of rabies virus. Six daily intravenous inoculations of 1.0 mg or 0.5 mg of poly I:C, beginning 3–24 hr before viral challenge, protected all rabbits infected with fixed virus. Three daily intramuscular injections of 0.5 mg of poly I:C, beginning 3 hr after viral challenge, protected rabbits infected with street virus. Experiments with fewer injections of poly I:C were not done. Intramuscular injections of poly I:C produced a local interferon response, and a suggestion of better protection was seen in rabbits given poly I:C in the same muscle site as the virus. Street virus-infected mice were protected by as little as 1.3 µg of poly I:C, and the intramuscular route of injection gave better protection than the intraperitoneal route. Protection could be seen in mice inoculated with poly I:C as long as 67 hr after injection of street virus.