[Characterization of leptospiral DNA by southern hybridization serovar lai recombinant probe pCX7]

The recombinant probe pCX7, derived from genomic library of serovar lai strain 017, was applied for the characterization of DNA from 20 strains of leptospires in different genus species, sero-groups and serovars by southern hybridization. The probe, specific to partial species L. interrogans, did not hybridized with DNA of L. biflexa strain Patoc I and L. illini strain 3055, neither with DNA of serovars javanica, manhao 2 and ranarum which had shown very weak virulence, but hybridized with DNA of the other 15 strains of L. interrogans in 8 serogroups. It was easy to distinguish the banding patterns, since the pCX7 probe hybridized with a limited number of DNA fragments. Different leptospires showed different banding patterns. A few differences between strain 017 (strain of strong virulence) and strain 601 (strain of weak virulence) of serovar Lai were observed although their hybridization banding patterns were very similar. Differences in hybridization signals in combination with the banding pattern appear to provide good characteristics for identification of leptospiral serogroups and serovars, even strains. The result indicated that southern hybridization with the probe pCX7 might provide good tools for identification of leptospira.