Antigenic and structural relatedness among non-capsid and capsid polypeptides of polioviruses belonging to different serotypes.

Antibodies were raised by immunization of Macaca fascicularis monkeys with extracts of M. fascicularis kidney cells separately infected with one of the three poliovirus serotypes. Preparations of antibodies were shown to be strictly type-specific in the neutralization test but formed immune complexes adsorbable on Staphylococcus aureus, Cowan I strain cells, with heterotypic as well as homotypic virus-specific polypeptides present in extracts from the virus-infected cells. The presence of intertypic antigenic determinants was demonstrated by this technique on both the non-capsid and capsid poliovirus polypeptides. Structural variations of poliovirus polypeptides were studied by analysing products of their partial proteolysis. Non-capsid polypeptides encoded in the central portion of the virus genome (polypeptides 5b and X) as well as in the 3'-terminal region (NCVP2 and NCVP4) were found to be highly conserved, whereas capsid polypeptides VP1, VP2, and VP3, which are encoded in the 5'-terminal region of the virus RNA, displayed a much greater variability.