Identification of a Tick Midgut Protein Involved in Infection of Female Ticks.

is an important biological vector as it transmits several pathogens, including , the causative agent of bovine babesiosis. The available strategies for controlling are limited, resulting in substantial challenges for both animal health and livestock management. Infection of the tick midgut is the essential first step for the transmission cycle of , yet this process remains largely unexamined. To better understand the first step of tick infection, this study employed a proteomic approach to identify a midgut protein that responds to infection. We then used RNA interference for gene silencing to determine if the protein is essential for infection. The protein we identified, Rm24, is twofold upregulated in the tick midgut during infection. We silenced the gene encoding Rm24 and examined the effect of reduced expression on both tick fitness and infection. Our results indicated that silencing the Rm24 gene impacted the survivability of adult female ticks, which exhibited a significant reduction in viability as compared to the control and non-injected groups. Importantly, we found that suppressing the gene encoding Rm24 led to a significant decrease in the number of engorged female ticks infected, with only 15% of female ticks testing positive for kinetes as compared to over 50% in the control groups. We also detected a significant reduction in vertical transmission of to larval progenies. These findings suggest that the Rm24 protein is critical for infection by and could serve as a promising target for future transmission-blocking strategies.