The comparison of neutralization indices (SMIT & WILTERDINK, 1966) was used for the intratypic serodifferentiation of 49 strains of poliovirus of types 1, 2 and 3, isolated from clinical cases with and without known contact with Sabin oral vaccine. This method was, as well, compared with the Wecker test and the RCT40 marker, in relation to the strains of poliovirus of type 3. The immune sera used in the neutralization tests were obtained from guinea pigs inoculated with vaccine strains […]