Detection of a new Arsenophonus-type bacterium in Canadian populations of the Rocky Mountain wood tick, Dermacentor andersoni.

Ticks of the genus Dermacentor are important vectors of human and animal pathogens in North America. They also carry a variety of endosymbiotic (i.e. non-pathogenic) bacteria. The American dog tick, D. variabilis, is known to be infected with gammaproteobacteria of the genus Arsenophonus. However, there have been no previous reports of Arsenophonus-type bacteria in the Rocky Mountain wood tick, D. andersoni, a species that is sympatric with D. variabilis in the western parts of its distributional range. In this study, the presence of Arsenophonus-type bacteria was determined by PCR and DNA sequencing for 338 D. andersoni and 448 D. variabilis adults from western Canada. Fifty-one (15%) of the D. andersoni were found to be infected with Arsenophonus, whereas only a single D. variabilis was infected. The prevalence of Arsenophonus in D. andersoni varied among localities (0-27%). The 16S rDNA sequences of Arsenophonus in Canadian D. andersoni and D. variabilis were identical to one another, but the results of a phylogenetic analysis showed that they were genetically distinct from, and may represent a different species to, the Arsenophonus in D. variabilis and Amblyomma americanum in eastern USA.