Comparative Microbiome Analysis of Three Epidemiologically Important Tick Species in Latvia.

(1) Background: Amplicon-based 16S rRNA profiling is widely used to study whole communities of prokaryotes in many niches. Here, we comparatively examined the microbial composition of three tick species, , and , which were field-collected in Latvia. (2) Methods: Tick DNA samples were used for microbiome analysis targeting bacterial 16S rDNA using next-generation sequencing (NGS). (3) Results: The results showed significant differences in microbial species diversity and composition by tick species and life stage. A close similarity between microbiomes of and ticks was observed, while the microbiome composition appeared to be more distinct. Significant differences in alpha and beta microbial diversity were observed between tick life stages and sexes, with lower taxa richness indexes obtained for female ticks. The genus was closely associated with ticks, while endosymbionts and were associated with and females, respectively. In females, the endosymbiont load negatively correlated with the presence of the genus. (4) Conclusions: The results of this study revealed important associations between ticks and their microbial community and highlighted the microbiome features of three tick species in Latvia.