Characterization of a double avirulent mutant of rabies virus and its potency as a vaccine, live or inactivated.

A strain bearing two mutations which abolish the virulence for adult animals after intracerebral or intramuscular inoculation has been constructed from the CVS strain of rabies virus. This apathogenic phenotype is stable after three successive passages of the double mutant in suckling mice brain. Trials of vaccination performed on mice in parallel with the double mutant and CVS both inactivated with beta-propiolactone indicate that the mutant is at least as efficient as CVS. This strain has also been found to be efficient as a live virus vaccine.