Antigenic modification of attenuated Sabin type 1 poliovirus by in vitro passages at supraoptimal temperatures.

Mutants were selected from Sabin type 1 attenuated poliovirus (LSc2ab strain), capable of growing at a high temperature (39.5 degrees C). They proved to be neurovirulent for monkeys. No correlation was found between neurovirulence and antigenic structure in Sabin type 1 virus as demonstrated by the analysis of the neutralization epitope formulae of thermo-resistant, neurovirulent mutants derived from LSs2ab strain. The lack of correlation between the antigenic pattern of the virus and the virulence was also confirmed by a mutant resistant to neutralization with monoclonal antibodies derived from the wild Mahoney parent of the Sabin type 1 virus. This mutant continued to be neurovirulent in spite of the complete conversion of its neutralization epitope formula to the Sabin virus pattern.