Sequence analysis and serological responses against Borrelia turicatae BipA, a putative species-specific antigen

PLoS Negl Trop Dis. 2013 Sep 19;7(9):e2454. doi: 10.1371/journal.pntd.0002454. eCollection 2013.


Background: Relapsing fever spirochetes are global yet neglected pathogens causing recurrent febrile episodes, chills, nausea, vomiting, and pregnancy complications. Given these nonspecific clinical manifestations, improving diagnostic assays for relapsing fever spirochetes will allow for identification of endemic foci and expedite proper treatment. Previously, an antigen designated the Borrelia immunogenic protein A (BipA) was identified in the North American species Borrelia hermsii. Thus far, BipA appears unique to relapsing fever spirochetes. The antigen remains unidentified outside of these pathogens, while interspecies amino acid identity for BipA in relapsing fever spirochetes is only 24-36%. The current study investigated the immunogenicity of BipA in Borrelia turicatae, a species distributed in the southern United States and Latin America.

Methodology/principal findings: bipA was amplified from six isolates of Borrelia turicatae, and sequence analysis demonstrated that the gene is conserved among isolates. A tick transmission system was developed for B. turicatae in mice and a canine, two likely vertebrate hosts, which enabled the evaluation of serological responses against recombinant BipA (rBipA). These studies indicated that BipA is antigenic in both animal systems after infection by tick bite, yet serum antibodies failed to bind to B. hermsii rBipA at a detectable level. Moreover, mice continued to generate an antibody response against BipA one year after the initial infection, further demonstrating the protein's potential toward identifying endemic foci for B. turicatae.

Conclusions/significance: These initial studies support the hypothesis that BipA is a spirochete antigen unique to a relapsing fever Borrelia species, and could be used to improve efforts for identifying B. turicatae endemic regions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Bacterial / blood
  • Antigens, Bacterial / genetics*
  • Antigens, Bacterial / immunology*
  • Borrelia / genetics*
  • Borrelia / immunology*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Dogs
  • Immunoassay / methods
  • Latin America
  • Mice
  • Molecular Sequence Data
  • Relapsing Fever / diagnosis*
  • Sequence Analysis, DNA
  • United States


  • Antibodies, Bacterial
  • Antigens, Bacterial
  • DNA, Bacterial

Associated data

  • GENBANK/KC845527
  • GENBANK/KC845528
  • GENBANK/KC845529
  • GENBANK/KC845530
  • GENBANK/KC845531

Grants and funding

This study was accomplished using startup funds provided by Mississippi State University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.