1959 Volume 21 Issue 5 Pages 265-280
In the present experiments with the original and the mouse-adapted virus of fowl pest, the infectivity of guinea pigs and virus distribution in their internal organs and nerve were investigated, and the following observations were made. 1. In the intracerebral inoculation of virus of fowl origin, the difference of infectivity for the guinea pig was derived from that of materials for inoculation, among which spleen emulsion was more infective than brain emulsion. 2. The infection with visible symptoms was caused more easily by mouse-adapted virus than virus of fowl origin. The symptoms were not shown in primary passage, but serial passages with mouse-adapted fowl pest virus were very possible in guinea pigs. 3. The infection with guinea-pig passaged virus was caused by either one of the intracerebral, intraperitoneal, subcutaneous, intranasal and peroral routes, with nervous symptoms shown in most cases. 4. It was delicate to appreciate the essential modification of fowl pest virus, but the development of lesions was decreased with the proceeding of passages. The depression of nosogenicity in the fowl was recognized as the modification of virus which caused no original lesions in the fowl by any inoculation route. 5. The incubation period in guinea pigs was 5 to 7 days in a great majority of cases, and scarcely influenced by the body weight of individual guinea pigs. Ii was longer in those intraperitoneally injected than in those intracerebrally injected. 6. The virus which intraperitoneally passaged through guiea pigs was at least obligatery neurotropic in guinea-pig passage.
