What you need to know: In addition to pathogens, ticks coexist and interact with symbionts, and commensal bacteria that together form an ecological unit, the tick holobiont. The holobiont is an additional organismal level on which natural selection operates. The components of the tick hologenome, composed of host and microbiome genomes, are complimentary. In agreement with this proposition, antibiotic treatment produces disturbance of the tick-microbiota homeostasis which in turn decreases tick fitness and affects tick-pathogen interactions. The use of broad spectrum antimicrobial compounds, such as antibiotics, targeting several bacterial species does not allow establishing causal links between the reduction of specific taxa abundance in tick microbiota and changes in tick physiology or pathogen colonization. The lack of tools for the precise manipulation of the tick microbiome is currently a major limitation to achieve mechanistic insights into the tick microbiome.
Anti-tick microbiota vaccines were recently introduced as a tool to target the microbiota of vector arthropods by immunizing the vertebrate hosts against live keystone bacteria or tick microbiota bacterial proteins. This tool can also be used to target tick endosymbionts. Decreased abundance of selected keystone bacteria and/or endosymbionts may reshape the structure of tick microbial communities in a predictable manner. This tool can be used to manipulate the tick microbiome against ticks and transmitted pathogens.
Où on va? Antimicrobiota vaccines can be used to manipulate the tick microbiome and control tick-borne pathogens in livestock (see below). Ticks collected in areas endemic for tick-borne pathogens can be processed for 16S rRNA amplicon sequencing to characterize the taxonomic profiles of the microbiome in infected ticks. Co-occurrence networks can be used to identify keystone bacteria potentially involved in facilitation of pathogen infection. Selected keystone bacteria can be used in antimicrobiota vaccines, to be formulated and tested in the lab for antigenicity and blocking of pathogen transmission. Selected vaccine candidates can be used in the field for the control of tick-borne pathogens.