Possible role of protein(s) as antigenic determinant of the type-specific main antigen of Leptospira kremastos strain Kyoto.

Acid hydrolysates of the type-specific main (TM) antigen isolated from Leptospira kremastos strain Kyoto showed a considerable inhibition of complement fixation reaction between TM antigen and anti-strain Kyoto serum. A fraction of 2 N HCl hydrolysate containing exclusively a large amount of neutral sugars showed no inhibition, whereas another fraction containing only a small amount of protein(s) showed a slight inhibition. The remaining fractions containing amino sugars, protein(s), and neutral sugars showed a slight inhibition, but the inhibition did not correlate with the amount of amino sugars. TM antigen, delipidized by hydrolysis with 1 N HCl for 4 min and then dialysis, showed a strong inhibition. The lipid fraction did not show any inhibition. The inhibitory effect of nondialyzable delipidized TM antigen was completely lost by treating the antigen with proteolytic enzymes, indicating that the antigenic determinant of L. kremastos strain Kyoto is intimately related with protein(s).