The genus Borrelia reloaded

PLoS One. 2018 Dec 26;13(12):e0208432. doi: 10.1371/journal.pone.0208432. eCollection 2018.


The genus Borrelia, originally described by Swellengrebel in 1907, contains tick- or louse-transmitted spirochetes belonging to the relapsing fever (RF) group of spirochetes, the Lyme borreliosis (LB) group of spirochetes and spirochetes that form intermittent clades. In 2014 it was proposed that the genus Borrelia should be separated into two genera; Borrelia Swellengrebel 1907 emend. Adeolu and Gupta 2014 containing RF spirochetes and Borreliella Adeolu and Gupta 2014 containing LB group of spirochetes. In this study we conducted an analysis based on a method that is suitable for bacterial genus demarcation, the percentage of conserved proteins (POCP). We included RF group species, LB group species and two species belonging to intermittent clades, Borrelia turcica Güner et al. 2004 and Candidatus Borrelia tachyglossi Loh et al. 2017. These analyses convincingly showed that all groups of spirochetes belong into one genus and we propose to emend, and re-unite all groups in, the genus Borrelia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Borrelia / classification*
  • Borrelia / genetics*
  • Borrelia Infections / microbiology*
  • DNA, Bacterial / analysis
  • Host Microbial Interactions / genetics
  • Host Specificity / genetics
  • Humans
  • Lyme Disease / microbiology
  • Phylogeny
  • Relapsing Fever / microbiology
  • Sequence Analysis, DNA


  • DNA, Bacterial

Grant support

This study was part-funded by the Australian Postgraduate Award (AG), the International Postgraduate Research Scholarship (SML), the Australian Research Council (LP160100200 to CO), Bayer HealthCare (Germany) and Bayer Australia, the Murdoch University Small Grant Scheme (CO), the Robert-Koch-Institute via the German National Reference Centre for Borrelia (VF), and ESCMID via a ESGBOR Study Group grant 2015 (GM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.