Specificity of leptospiricidal activity test mediated by antiserum and complement.

A leptospiricidal activity test mediated by immune serum plus guinea pig complement using 11 serovars of leptospiras belonging to 3 serogroups, Icterohaemorrhagiae, Pomona and Mini, indicated that the reaction was generally serogroup-specific. The immune serum from which the homologous or heterologous agglutinin was absorbed was then examined with the result that the anti-L. icterohaemorrhagiae and anti-L. sarmin antisera which absorbed with L. icterohaemorrhagiae and L. sarmin respectively did not agglutinate, but instead destroyed their homologous leptospiras in conjunction with complement. Many of the antisera which absorbed with the heterologous serovars did not agglutinate, but instead destroyed their respective heterologous strain. These findings indicate that the leptospiricidal activity test is more sensitive and more cross reactive than agglutination.