Revisiting Wolbachia supergroup typing based on WSP: spurious lineages and discordance with MLST

Curr Microbiol. 2007 Jul;55(1):81-7. doi: 10.1007/s00284-007-0055-8. Epub 2007 Jun 5.

Abstract

The obligate intracellular bacteria Wolbachia are taxonomically subdivided into eight supergroups (named A-H). Supergroup typing of strains has been mostly based on phylogenetic inference of the Wolbachia surface protein (wsp), a gene that recently has been shown to experience high rates of recombination. This brings into question its suitability not only for microtaxonomy, but also for supergroup classification of the genus. A Multilocus Sequence Typing (MLST) scheme for Wolbachia has recently been developed that types strains based on five conserved genes, thus providing a rigorous supergroup annotation of strains. Here we report striking discrepancies in supergroup designation between MLST and wsp inferences, and propose a revision of current methods for Wolbachia supergroup typing. Transfer of whole wsp gene sequences between supergroups A and B has occurred. Furthermore, as a result of intragenic recombination, wsp phylogeny creates spurious basal lineages that are not supported by MLST. For example, the proposed supergroup G, based upon wsp alone, likely represents only a wsp recombinant clade. Removal of supergroup G is advised until and unless the existence of this lineage is substantiated by other sequence information (e.g., MLST). We recommend a full characterization MLST for a correct strain typing, while, based on the current data set, use of a single MLST gene can be effective for supergroup designation of A and B strains. Finally, we note that the sharing of wsp sequences between A and B strains indicates a strong genetic cohesiveness of Wolbachia strains, supporting designation of these bacteria within the same species, W. pipientis.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Outer Membrane Proteins / genetics*
  • Bacterial Typing Techniques / methods*
  • DNA, Bacterial / genetics
  • Genotype
  • Phylogeny
  • Sequence Analysis, DNA
  • Sequence Homology
  • Wolbachia / classification*
  • Wolbachia / genetics*

Substances

  • Bacterial Outer Membrane Proteins
  • DNA, Bacterial
  • Wsp protein, Wolbachia