Serovar Identification and Genetic Characterization of Leptospira Isolates by Arbitrarily Primed PCR and Ribotyping

ABSTRACT

Serovars of 22 leptospiral field isolates from rats trapped in Korea were identified by cross-agglutinin absorption test (CAAT). Genomic characteristics of 7 selected isolates and 6 antigenically closely related reference serovars of lai, yeonchon, birkini, gem, mwogolo, and canicola were differentiated by arbitrarily primed PCR (AP-PCR) and southern blot hybridization using 16S rRNA gene probe from Borrelia burgdorferi. Among the 22 isolates, 21 strains were identified as serovar lai by CAAT, while the serological reactivity of NR13 did not accord with that of serovar lai. Results of AP-PCR using primers RSP, KF and PB-1 were in general agreement with those obtained by serological identification, and all 7 isolates including NR13 showed the same profile with serovar lai or yeonchon. In the southern blot hybridization with 16S rRNA gene probe, the isolates were divided into two ribotype groups when HindIII and BamHI digests were employed: isolates NR4, NR13, and serovar lai showed the same profile, and isolates JR34, JR57, KR48, JR77, and JR82 were classified as the another ribotype group. Isolate NR13 and serovar yeonchon, which were isolated in Korea and showed serological differences with serovar lai, were indistinguishable from serovar lai in this DNA study using AP-PCR and ribotyping. These results demonstrate that Korean leptospiral isolates were closely related in DNA level, and ribotyping would be useful for subgrouping of field isolates.