Nucleic acid probe characterizes Leptospira interrogans serovars by restriction fragment length polymorphisms.

Restriction endonuclease analysis (REA) of genomic DNA can discriminate between many Leptospira interrogans serovars. However, several serovars have similar restriction endonuclease digestion patterns which prohibits accurate identification. This investigation expands previous REA studies of L. interrogans to include serovars in serogroup Tarassovi. Most serovars in this serogroup had characteristic digestion patterns by which they could be identified. However, four of the serovars in this serogroup had similar digestion patterns, thus preventing serovar identification by REA alone. To discriminate between these serovars REA was supplemented with Southern blot analysis. The DNA from each serovar showed similar but unique patterns when hybridized with a probe synthesized from a repetitive sequence element cloned from L. interrogans serovar hardjo type hardjo-bovis. The applicability of this technique to characterize other serogroups was assessed. One hundred sixty six of 190 serovars screened by Southern blot analysis contained sequences which hybridized with the repetitive element probe under conditions of relaxed stringency. These results suggest that Southern blot analysis using this probe will be a valuable supplement for typing L. interrogans.