Unfed adult
Ixodes persulcatus ticks were collected from four locations of Nagano and Hokkaido in Japan. Infected
Borrelia garinii were investigated by PCR-RFLP of the
ospA and
ospB gene sequences. The primer set amplified an approximately, 1.6-kb DNA fragment (0.7-kb in some strains), and
BsrI,
BstYI, or
NlaIII digestion of the product resulted in six distinctively different PCR-RFLP groups and two independent borrelial strains. The representatives in each PCR-RFLP group and individuals from the borrelial strains were sequenced, and their deduced amino acid sequences were aligned. A neighbor-joining phylogenetic analysis showed that the
B. garinii OspA or OspB sequences were each divided into three major clusters including isolates from both the Nagano and Hokkaido locations. There was no local difference in OspA/B sequences between Nagano and Hokkaido. The
osp gene of
Borrelia burgdorferi sensu lato is highly heterogeneous, and this was also confirmed by our sequence analysis. Some strains of the different PCR-RFLP groups had closely related OspA sequences, while the OspB seqences of these strains were quite different. These findings suggested intraspecies gene exchange and recombination events between the two genes in
B. garinii.
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