Grappling with the tick microbiome.

Ixodes scapularis and Ixodes pacificus are the predominant vectors of multiple human pathogens, including Borrelia burgdorferi , one of the causative agents of Lyme disease in North America. Differences in the habitats and host preferences of these closely related tick species present an opportunity to examine key aspects of the tick microbiome. While advances in sequencing technologies have accelerated a descriptive understanding of the tick microbiome, molecular and mechanistic insights into the tick microbiome are only beginning to emerge. Progress is stymied by technical difficulties in manipulating the microbiome and by biological variables related to the life cycle of Ixodid ticks. This review highlights these challenges and examines avenues to understand the significance of the tick microbiome in tick biology. Ixodes scapularis and Ixodes pacificus harbor a simple primary microbiome composed predominantly of the endosymbiont Rickettsia buchneri. The tick microbiome also includes microbiota acquired from the environment and represents a transient microbiome. The tick microbiome composition is in a state of flux and is likely influenced by multiple biotic and abiotic factors. The microbiome composition is regulated by immune responses of the tick at the vector–host and environment–vector interfaces. Understanding the interactions between the tick microbiota, tick-borne pathogens and tick immune responses will reveal new insights in tick biology. [ABSTRACT FROM AUTHOR]