SERODIFFERENTIATION OF POLIOVIRUS STRAINS: II. MODIFIED WECKER TEST ON TYPE 3 POLIOVIRUS STRAINS

The intratypic serodifferentiation test of type 3 polioviruses was carried out with the modified Wecker technique using anti-Sabin 3 rabbit sera. Thirty-four vaccine-related and 28 nonvaccine-related strains were examined. Of the 34 vaccine-related strains, 30 were classified as vaccine-like, 3 as intermediate, and one as nonvaccine-like. Out of 28 wild strains tested, 12 were classified as nonvaccine-like, 7 as intermediate, and 9 as vaccine-like. These results showed that with the modified Wecker technique, vaccinerelated virus could be classified as vaccine-like, whereas some of the wild type 3 poliovirus isolated in Japan were indistinguishable antigenically from the Sabin type 3 vaccine virus. For the more conclusive differentiation of type 3 polio strains, it was needed to carry out comparative studies of these strains by the McBride and modified Wecker techniques.