Homology of variable major protein genes between Borrelia hermsii and Borrelia miyamotoi

Antigenic variation has been studied in detail for the etiological agent of relapsing fever, Borrelia hermsii. The variable major proteins (vmps) are found at its cell surface, enabling it to avoid the host's immune response. We have cloned and sequenced the omp-gene (vmp)-like sequences from the Borrelia miyamotoi strains HT31 and FR64b and the deduced amino acid sequences were compared with the published vmp proteins vmp3, vmp24, and vmp33 of B. hermsii. The sequences were aligned and revealed pairwise sequence identities ranging from 45 to 51%, and differences were scattered throughout the sequences. Southern hybridization using the cloned ump-like sequence of strain HT31 as a probe suggested that the vmp homologues reside on the linear plasmids of B. miyamotoi. The probe hybridized weakly with B. hermsii linear plasmids and restriction digests. These results suggest that B. miyamotoi has sequences resembling the ump genes in B. hermsii.