IMMUNOLOGICAL AND GENETIC ANALYSES OF VMPA OF A NEUROTROPIC STRAIN OFBORRELIA-TURICATAE

In mice infected with serotype A but not serotype B of the relapsing f ever spirochete Borrelia turicatae, early invasion of the brain occurs , Serotypes A and B are further distinguished by the abundant surface protein they produce: VmpA and VmpB, respectively, Western blotting wi th monoclonal antibodies, one-dimensional peptide mapping, and partial amino acid sequencing demonstrated regions of the VmpA protein that d iffered from VmpB, Oligonucleotide primers based on the partial amino acid sequences of unique regions were used to amplify a portion of the VmpA gene (vmpA) by PCR, and the product was used as a probe in South ern blot and Northern blot analyses, These experiments showed that (i) expression of the vmpA sequence was determined at the level of transc ription and (ii) the vmpA sequence was in two locations in serotype A and one location in serotype B, The vmpA gene at the expression-linked locus of serotype A was cloned and sequenced, An open reading frame w ould encode a polypeptide of 214 amino acids, The polypeptide expresse d by Escherichia coli was bound by VmA-specific but not VmpB-specific antibody, Primer extension analysis identified a consensus sigma(70)-t ype promoter for vmpA at the expression locus, Phylogenetic analysis r evealed that VmpA is homologous to small Vmp (Vsp) proteins of B, herm sii and to OspC proteins of B. burgdorferi. These findings indicate th at a function of the Vsp-OspC family of proteins of Borrelia spp, may be differential localization in organs, including the brain, during in fection.