PURIFICATION AND CHARACTERIZATION OF A PROTEIN ANTIGEN FROM LEPTOSPIRA-INTERROGANS SEROVAR HARDJO, COMMON TO A WIDE-RANGE OF BACTERIA

A protein with a molecular mass of 64 kDa (P64) from Leptospira interrogans serovar hardjo was partially purified by using successively, phase partitioning with Triton X-114, ion-exchange chromatography and sucrose gradient centrifugation. Purification to homogeneity was obtained by electroelution of P64 from SDS-polyacrylamide gels. Monospecific rabbit antiserum (RαP64) was prepared using the purified protein preparation. P64 had a native molecular mass of >670 kDa and was recognized by RαP64 as well as by human antisera. Western blotting of leptospiral serovars and 18 other bacterial species with RαP64 showed that P64 was cross-reactive with an equivalent antigen in a wide range of bacteria, indicating that it belongs to a family of antigens previously designated 'common antigen'. This putative common antigen from Leptospira appears to have a sub-surface location, but its function is not yet known.