Immunodominant epitope in the C-terminus of a variable major protein in Borrelia duttonii, an agent of tick-borne relapsing fever.

Borrelia duttonii strain Ly was isolated from a child with tick-borne relapsing fever in Tanzania. B. duttonii produces variable major proteins (Vmps), which undergo antigenic variation. We previously reported transcription of the vmpP gene, which is one of the Vmp genes in strain Ly, detected in vitro cultivation. In the current study, we purified the recombinant non-lipidated VmpP protein by affinity chromatography and produced VmpP polyclonal antibodies. Antigenicity of VmpP was examined by Western immunoblot analysis and peptide-based enzyme-linked immunosorbent assays. Antigenic epitopes were shown to comprise five regions interspersed within the VmpP primary amino acid sequence. Synthetic peptides spanning residues of three of five regions, 232-237 (LASIVD), 280-285 (AGGIAL), and 350-355 (KAADQQ), reacted strongly with the VmpP-specific antibody and these residues were identified as epitopes. In particular, the C-terminal domain (KAADQQ) of this protein was immunoreactive. Further research based on our results will promote the development of a recombinant vaccine for B. duttonii infection.