The Dermacentor andersoni microbiome and pathogen acquisition

Ticks are obligate hematophagous ecoparasitic arthropods that feed on vertebrates. In addition to being important pests of livestock in their own right, ticks are also the first and second most important vector of disease for livestock and humans, respectively.  The Rocky Mountain wood tick, Dermacentor andersoni, vectors Anaplasma marginale, which causes bovine anaplasmosis, the most widespread tick-borne pathogen of cattle worldwide.  The goal of this study is to determine whether the bacterial microbiome of D. andersoni affects the ability to acquire A. marginale.

We have identified two populations of D. andersoni ticks with differing vector competence for A. marginale: ticks from Burns, Oregon had a high A. marginale acquisition rate (60%) while ticks from Lake Como, Montana had a low A. marginale acquisition rate (20%).  We have characterized the bacterial microbiome of these two populations by deep sequencing 16S rDNA amplicons. We exposed ticks from both locations to antibiotics to disrupt the bacterial microbiome, and then performed A. marginale acquisition studies to determine if antibiotic exposure affected vector competence.

Our study has shown that the bacterial microbiome is tissue-specific and varies in the two populations of ticks. Disruption of the microbiome through antibiotic exposure influences the ability of D. andersoni to acquire pathogens.  Manipulation of the tick microbiome may provide avenues to limit transmission of tick borne diseases.