Isolation and Chemical Composition of Complement-Fixing Antigens From Leptospires

Summary A chemical separation procedure which yields four arbitrary cell fractions has been developed and applied to three serotypes of leptospires. The four complement-fixing fractions are non-dialyzable, pentose-containing materials, the serological activities of which have been measured semi-quantitatively. One or more complement-fixing principles, of nature not yet known, are concentrated in two chemically distinct, relatively free of protein, polysaccharide-containing cell fractions. The protein constituent (Fraction 3) of the leptospiral cell was poorly reactive in the complement fixation test. Spectrophotometric differences among preparations of Fraction 2 from three serotypes may prove to be an aid in the differentiation of serotypes.