Reclassification of North American leptospiral isolates belonging to serogroups Mini and Sejroe by restriction endonuclease analysis.

The genomes of North American strains of leptospires belonging to serogroups Mini and Sejroe were analyzed and compared with those of reference strains by cleavage with restriction endonucleases. The isolates selected for this study, when typed by the serologic method, were identified as serovars szwajizak, hardjo, and balcanica. However, the results of restriction endonuclease analysis (REA) indicated that a different classification existed. The 2 isolates typed as serovar szwajizak seem to be georgia by REA. Isolates belonging to serovars balcanica and hardjo had REA patterns that differed from both reference strains. Differences were not observed in the REA patterns between balcanica and hardjo isolates. All hardjo and balcanica isolates examined are suggested to be classified into a previously described hardjo, REA subtype hardjobovis. Using the enzyme Hha1, these isolates were subdivided into 3 subgroups. When examining the REA pattern of the 17 reference strains in serogroup Sejroe, 3 identical pairs were observed: wolffi and roumanica; sejroe and polonica; and istrica and nyanza. The REA again indicated that it will be a valuable method for the classification of leptospires.