Consensus sequence on the genes encoding the major outer surface proteins (OspA and OspB) of Borrelia garinii isolate

Japanese Lyme borrelias classified as ribotype IV is predominant among isolates derived from clinical specimens, reservoir rodents and Ixodes persulcatus ticks, and has been characterized as Borrelia garinii. These B. garinii isolates have antigenic and genetic features apparently different from North American, European and other Asian isolates, especially in major outer surface proteins A (OspA) and B (OspB). In this study, we cloned and sequenced the genes encoding OspA and OspB from B. garinii strain FujiP2 (ribotype IV strain) isolated from I. persulcatus in Shizuoka, Japan. A sequence analysis revealed significant differences to the previously published sequences of ospA and ospB of B. burgdorferi sensu lato. The open reading frames of ospA and ospB consist of 822 and 888 nucleotides corresponding to the proteins of 273 and 295 amino acids, with molecular weights of 29,643 and 31,786 daltons, respectively. The most interesting finding is that the two osp genes share a consensus 282 bp sequence in their carboxy-terminal portions and that the ospB gene is flanked by a 282 bp-long direct repeat sequence. The deduced amino-acid (aa) sequences of OspA and OspB of strain FujiP2 showed 60.1% homology, and have overall similarities of 70.5%, 70.3% and 75.6% to OspAB proteins of B. burgdorferi sensu stricto strain B31, Borrelia afzelii strain ACA1 and Borrelia garinii strain Ip90, respectively.