Adaptation, attenuation and plaque purification of a rabiesvirus isolate (V319) from a vampire bat (Desmodus rotundus).

Five rabiesvirus isolates, four of vampire bat origin and one from the brain of a rabid cow, were studied with respect to their adaptability to tissue culture. Only two strains (V319 and Mazatan strains) adapted readily. One (Mazatan) failed to yield high titers in vitro after isolation, plaque purification and further passage; however, the V319 strain routinely yielded titers of 10(9) PFU/ml. In limited pathogenicity tests in cattle and dogs, the V319 strain was found not to be excreted in the saliva of inoculated animals. Strain V319 was innocuous to cattle and dogs by the intramuscular route of inoculation, but it was still pathogenic by the intracerebral route. It also was found pathogenic for suckling and 21-day-old mice following inoculation by the intracerebral route. If given by the intramuscular route to mice of both ages, however, strain V319 was of low virulence. It was not virulent for mice when administered by the intraperitoneal route. It was concluded that strain V319 (plaque 476) possessed suitable characteristics for a potential vaccine.