Tick-borne pathogens are ubiquitously present throughout the world and represent concerns for human and animal health. Although the development of vaccines and vector control programs have reduced the threat of tick-borne disease, the emergence or re-emergence of these diseases is still a relevant threat today. Therefore, novel targets are needed for continued control of ticks. Ticks are hematophagous arthropods and rely on the multifunctional salivary gland to ensure adequate blood meal acquisition and osmoregulation. Although salivation into the host occurs quickly upon feeding, pathogen transmission requires 16-48 hours of feeding time, suggesting it is possible to prevent disease transmission through interruption of feeding after attachment or altering osmoregulatory capabilities. Unfortunately, an understanding of the primary machinery required for proper salivary gland function within ticks is limited. Therefore, the objective of this study was to test the hypothesis that K+ ion channels and transporters represent an ion conductance pathway required for proper salivary gland function and are putative targets for insecticide design. Proof-of-concept studies were performed in Drosophila melanogaster to determine the influence K+ channel inhibition has on sucrose consumption. Preliminary data suggest that pharmacological inhibition of K+ channels significantly (P&lt;0.0001) reduces the total volume of sucrose solution ingested by individual flies and genetic depletion of salivary gland specific Kir channels increased the time required to obtain a complete meal by approximately 3-fold. In ticks, our data show that pharmacological modulation of K+ channels reduced the ability to salivate by 7.5-fold (~150 nl/5min to 20 nl/5min) and significantly (P &lt; 0.001) reduced the concentration of K+- and Na+- ions secreted in the saliva, suggesting inhibition of K+ ion flux hinders tick salivary gland function. To conclude, our data suggest K+ ion channels are critical for arthropod salivary gland function and are putative target sites for reducing tick-vectored diseases.

Characterizing the physiological role and toxicological potential of potassium transport pathways in the tick salivary gland

254th National Meeting (2017)

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