Extensive diversity of Rickettsiales bacteria in two species of ticks from China and the evolution of the Rickettsiales

Yan Jun Kang, Xiu Nian Diao, Gao Yu Zhao, Ming Hui Chen, Yanwen Xiong, Mang Shi, Wei Ming Fu, Yu Jiang Guo, Bao Pan, Xiao Ping Chen, Edward C. Holmes, Joseph J. Gillespie, Stephen J. Dumler, Yong Zhen Zhang

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Background: Bacteria of the order Rickettsiales (Alphaproteobacteria) are obligate intracellular parasites that infect species from virtually every major eukaryotic lineage. Several rickettsial genera harbor species that are significant emerging and re-emerging pathogens of humans. As species of Rickettsiales are associated with an extremely diverse host range, a better understanding of the historical associations between these bacteria and their hosts will provide important information on their evolutionary trajectories and, particularly, their potential emergence as pathogens. Results: Nine species of Rickettsiales (two in the genus Rickettsia, three in the genus Anaplasma, and four in the genus Ehrlichia) were identified in two species of hard ticks (Dermacentor nuttalli and Hyalomma asiaticum) from two geographic regions in Xinjiang through genetic analyses of 16S rRNA, gltA, and groEL gene sequences. Notably, two lineages of Ehrlichia and one lineage of Anaplasma were distinct from any known Rickettsiales, suggesting the presence of potentially novel species in ticks in Xinjiang. Our phylogenetic analyses revealed some topological differences between the phylogenies of the bacteria and their vectors, which led us to marginally reject a model of exclusive bacteria-vector co-divergence. Conclusions: Ticks are an important natural reservoir of many diverse species of Rickettsiales. In this work, we identified a single tick species that harbors multiple species of Rickettsiales, and uncovered extensive genetic diversity of these bacteria in two tick species from Xinjiang. Both bacteria-vector co-divergence and cross-species transmission appear to have played important roles in Rickettsiales evolution.

Original languageEnglish (US)
Article number167
JournalBMC Evolutionary Biology
Volume14
Issue number1
DOIs
StatePublished - Jul 30 2014
Externally publishedYes

Keywords

  • Co-divergence
  • Evolution
  • Phylogeny
  • Rickettsiales bacteria
  • Ticks
  • Vectors

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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