STUDIES ON COMPLEMENT FIXING ANTIGENS OF LEPTOSPIRAE

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Abstract
Methods of preparation of "whole" and type-specific antigens from leptospiral cultures for use in the complement fixation test are outlined. Leptospiral cultures grown in Korthof's medium were treated with pyridine and after appearance of a copious precipitate were centrifuged. The supernatants were dialyzed and after concentration by pervaporation were used as "whole" antigens. Type-specific antigens were prepared from acetone precipitates of filtrates of "whole" antigens. Considerable cross reaction was observed with "whole" antigens prepared from L. pomona, L. canicola, and L. icterohaemorrhagiae and their respective rabbit hyperimmune sera, although titers with homologous sera were invariably higher. These cross reactions, however, were not as pronounced with sera from cattle naturally infected with L. pomona, where approximately 43% of the sera reacted with homologous antigen only. No reactions were observed between the type-specific antigen and any of the heterologous sera employed. It has also been shown that with experimental sera type-specific antibodies appeared earlier and persisted longer than group-specific antibodies. In view of the above observations the use of polyvalent antigen for routine screening of leptospiral antisera is advocated. Type-specific antigens are recommended for use in more precise diagnosis.