IMMUNOLOGICAL CLASSIFICATION OF POLIOMYELITIS VIRUSES ISOLATED IN JAPAN

Poliomyelitis viruses have been immunologically grouped into three types, Brunhilde, Leon and Lansing. Although much of effort has been devoted to isolate poliomyelitis virus in Japan, little is revealed concerning the immunological property of the strains isolated.After World War II, the existence of poliomyelitis virus “Lansing” strain in Japan was suspected from the results obtained by the neutralization test on sera of the healthy Japanese, and furthermore, poliomyelitis virus B34 strain that was of Lansing type was successfully isolated from the stool of one healthy member of a polio patient's family, by means of mouse passage of the specimen. At that time monkeys were not used to isolate the causative agent of the disease because they were not easily available.An epidemic of poliomyelitis has occurred in the northern part of Japan during 1949. A total of 501 (12.5/100, 000 population) cases was reported from Hokkaido, and also 194 (18.9/100, 000 population) cases from Aomori Prefecture. These figures represent only paralytic cases, since in Japan nonparalytic cases are hardly diagnosed except in the epidemic season of poliomyelitis and mostly are not recognized as poliomyelitis. During this epidemic spinal cords of two patients (each aged one year and two years old) of whom one is from Shibetsu, Hokkaido and the other is from Hachinohe, Aomori Prefecture were obtained, and kept in dry ice box.Using monkeys as experimental animal two virus strains, named Hachinohe and Shibetsu strain were successfully isolated from these spinal cords in March 1950. However no virus was isolated by passages in mice. Both of the two strains newly isolated in monkeys were presumed not of “Lansing” type.In 1951 the Poliomyelitis Research Committee was set up by the request of the government, and we were nominated as one of the members participating in the activity. The study concerning the immunological classification of poliomyelitis viruses in Japan using monkeys was carried out.