The cell surface antigens of Streptococcus equi.

An analysis of the cell surface antigens of Streptococcus equi is presented. Following extraction from cell walls, whole cells and hyaluronidase treated cells the immunoprecipitation patterns of the intact and protease treated components were developed with rabbit anti serum against S. equi. It was determined by mouse protection tests that the specificity of protective antibodies was directed toward a trypsin labile antigen. The presence of antigens similar to those designated M and R in Group A streptococci were found in S. equi.