Infection-Mediated Shifts in the Microbial Communities of Deer-Fed Ixodes scapularis Ticks

The holobiont of the blacklegged tick (<i>Ixodes scapularis</i>) includes maternally inherited rickettsial endosymbionts and environmentally acquired microbes that may influence tick fitness and vector competence. While previous studies have focused on characterizing the microbiota of <i>I. scapularis</i> ticks, less is known about the influence of tick infection status on microbial assemblages. Here, we collected engorged female <i>I. scapularis ticks</i> from hunter-harvested white-tailed deer (<i>Odocoileus virginianus</i>) across 11 counties in Wisconsin during fall 2022. The ticks were maintained in laboratory conditions for oviposition and then frozen for nucleic acid extraction. The infection status of each tick was determined using qPCR, targeting <i>Borrelia</i> spp., <i>Babesia</i> spp., and Powassan virus. Bacterial and fungal communities were characterized through amplicon-based sequencing targeting the 16S rRNA gene and ITS2 region, respectively. Our targeted pathogen testing revealed that 14.1% of the collected ticks were infected with <i>Babesia odocoilei</i> and 23.3% with <i>Borrelia burgdorferi</i>. The microbial community composition of ticks was significantly influenced by infection status and pathogen identity. Notably, <i>Borrelia</i>-infected ticks exhibited distinct microbiota profiles and increased microbial network connectivity. These findings provide new insights into the microbial ecology of deer-fed <i>I. scapularis</i> ticks and highlight the role of infection in shaping both microbiota and mycobiota communities.