Vector competency is determined by the ability of the arthropod to acquire, amplify, and horizontally transmit the virus, thus mechanisms to inhibit these processes are likely to have deleterious consequences to arbovirus transmission. We employed structurally diverse modulators of ATP-sensitive inward rectifying potassium (KATP) channels to test if KATPchannels are a critical ion conductance pathway in the arthropod salivary gland that enables saliva secretion and vector competency. KATP channel activators reduced the ability of mosquitoes to ingest blood by up to 97.3% in a concentration-dependent manner. To determine if the failure to feed was due to inhibition of salivary gland function, we quantified secreted saliva from individual mosquitoes. Control mosquitoes were shown to secrete a mean of 1.2±0.3 nL whereas mosquitoes exposed to Kir channel modulators secreted a mean of 0.3±0.15 nL, a significant (P&lt;0.05) reduction in secretory activity. To test if KATP-mediated inhibition of the salivary gland altered vector competency of A. aegypti, we studied the acquisition and dissemination of Dengue virus 2 (DENV2). Data show DENV2 mRNA was not detected in any individual mosquito that fed on infected blood meals with KATP modulators, yet control mosquitoes had an infection rate of 60% and a mean DENV2 titer of 4e4 pfu/mL. In addition, horizontal transfer of DENV2 was reduced by 99% when exposed to KATP modulators, presumably due to reduced saliva secretion. In addition to mosquitoes, we aimed to test the functional relevance of Kir channels to salivary gland function of aphids, which are non-hematophagous arthropods. Inhibitors of classical Kir channels, but not KATP channels, reduced the length of the salivary sheath in a concentration dependent manner, indicating that the secretory activity of the aphid salivary gland is reduced by Kir inhibition. Next, we employed the electrical penetration graph (EPG) technique to measure the impact Kir inhibition has to aphid feeding biology. Foliar application of Kir inhibitors eliminated the E1 and E2 phases (phloem feeding) in all aphids studied, which corresponds to the observed reduced sheath formation. Contact exposure to VU041 after foliar applications toxic to A. gossypii at 72- and 96-hours post-infestation, indicating mortality is likely a result of starvation and not acute toxicity. Translation of these data to the development of novel antifeedant insecticides will be discussed.

Targeting kir channels to reduce vector competency of arthropods

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