Immunologic and genetic analyses of VmpA of a neurotropic strain of Borrelia turicatae

Abstract

In mice infected with serotype A but not serotype B of the relapsing fever 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 with monoclonal antibodies, one-dimensional peptide mapping, and partial amino acid sequencing demonstrated regions of the VmpA protein that differed 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 Southern blot and Northern blot analyses. These experiments showed that (i) expression of the vmpA sequence was determined at the level of transcription 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 would encode a polypeptide of 214 amino acids. The polypeptide expressed by Escherichia coli was bound by VmA-specific but not VmpB-specific antibody. Primer extension analysis identified a consensus 70-type promoter for vmpA at the expression locus. Phylogenetic analysis revealed that VmpA is homologous to small Vmp (Vsp) proteins of B. hermsii and to OspC proteins of B. burgdorferi. These findings indicate that a function of the Vsp-OspC family of proteins of Borrelia spp. may be differential localization in organs, including the brain, during infection.

Non‐heritable change of a spirochaete's phenotype by decoration of the cell surface with exogenous lipoproteins

“…Recombinant OspA is the basis of an effective human vaccine against B. burgdorferi infection (Steere et al, 1998), but among patients with Lyme disease immunological reactivity to OspA is also associated with a higher risk of an autoimmune-type arthritis (Kalish et al, 1993). The relapsing fever Borrelia spp., such as B. hermsii and B. turicatae, have on their surface Vsp and Vlp lipoproteins, which are involved with antigenic variation and are associated with different tissue localizations during mammalian infections (Barbour et al, 1982;Cadavid et al, 1993;Cadavid et al, 1997;Pennington et al, 1997;Schwan and Hinnebusch, 1998;Pennington et al, 1999). The outer membrane of spirochaetes also includes integral membrane proteins, such as the P66 protein (Probert et al, 1995;Skare et al, 1997;Bunikis et al, 1998).…”

Extensive interplasmidic duplications change the virulence phenotype of the relapsing fever agent Borrelia turicatae

“…The varying antigens of relapsing fever Borrelia spp. are lipoproteins of two types: variable small proteins (Vsps) of about 23 kDa and variable large proteins (Vlps) of about 38 kDa (Barbour et al, 1982;Burman et al, 1990;Carter et al, 1994;Cadavid et al, 1997). Each Vsp or Vlp is encoded by a different vsp or vlp gene.…”

“…The only detectable difference between serotypes A and B by one-dimensional protein electrophoresis was whether they produced VspA or VspB on their surfaces (Cadavid et al, 1994). These two proteins are antigenically distinct and differ at 40% of their residues, the greatest diversity being in their C-terminal halves (Cadavid et al, 1997;Pennington et al, 1999).…”

The 44‐kb Linear Plasmid Molecule in the Relapsing Fever Agent Borrelia duttonii Strain Ly Serve as a Preservation of vmp Genes

“…However, both Borrelia species display antigenic variation that allows it to escape host immune response. This mechanism has been extensively studied, and several vmp genes have been identified and have been divided into two families: vlp (variable large protein of average molecular weight, 33 36 kDa) and vsp (variable small protein, approximate molecular weight of 22 kDa) genes, on the basis of their molecular sizes (8,20).The genome of both relapsing fever and Lyme disease borreliae is composed of one linear chromosome of about one megabase and several linear and circular plasmid molecules (2,4,21,26). Some of these plasmids carry genes for variable major protein (Vmp) in relapsing fever borreliae and the outer surface membrane protein (Osp) in Lyme disease spirochetes (3,9).…”

“…However, both Borrelia species display antigenic variation that allows it to escape host immune response. This mechanism has been extensively studied, and several vmp genes have been identified and have been divided into two families: vlp (variable large protein of average molecular weight, 33 36 kDa) and vsp (variable small protein, approximate molecular weight of 22 kDa) genes, on the basis of their molecular sizes (8,20).…”