Further studies of specificity of antibodies contained in antiserum against poliovirus.

Antigenic components of Mahoney strain (poliovirus type 1) involved in virus neutralization reaction were analyzed with mutant Mahoney strains resistant to inhibitors in equine serum (inhibitor-resistant mutants) by means of the kinetic neutralization test. It was shown that absorption of anti-Mahoney serum with five inhibitor-resistant mutants yielded sera with different antibodies, of which three had distinct specificities and two specificities possibly partly related to one of those three sera. Further, it was found that step wise selection of Mahoney variants resistant to one, two, three and four different inhibitors resulted in gradual deviation of its antigenic composition from that of the original strain. From these results, the possible presence of three or more distinct antigenic determinant sites on the surface of Mahoney strain was indicated.