Characterization and manipulation of the bacterial microbiome of Dermacentor andersoni

Recent advances in sequencing are allowing investigators to explore those organisms that live within another. The bacterial microbiome is thought to play an important role in the health of the host and may impact diverse physiological processes.  While several studies of the insect microbiome have been undertaken, the tick microbiome remains largely unexplored.  We have recently characterized the microbiome from three populations of Dermacentor andersoni ticks with a view to understanding how the microbiome might impact pathogen acquisition.

We have identified three populations of D. andersoni ticks with differing vector competence for the rickettsia Anaplasma marginale, the most globally prevalent pathogen of cattle. Ticks from Reynolds Creek, Idaho have a high pathogen acquisition rate, ticks from Burns, Oregon, have an intermediate acquisition rate, while ticks from Lake Como, Montana have a low acquisition rate. We subjected a cohort of ticks from each location to antibiotics to manipulate the microbiome and then characterized the microbiomes by 16S sequencing.  We identified a species that was highly prevalent in the microbiome of ticks that displayed low pathogen acquisition rates but was present only at low levels in the other tick populations.  

We show that the bacterial microbiome is tissue-specific and varies in the populations of ticks. Additionally, we show that the microbiome changes over time in a lab setting as well as in the field. The microbiomes responded differently to antibiotic manipulation and manipulation had varying effects on pathogen acquisition. Microbiome manipulation may provide avenues to limit pathogen acquisition.