Dual-action salivary peptide drives black fly feeding efficiency

Black flies (Simulidae) employ salivary peptides to optimize blood-feeding efficiency through anticoagulation and analgesia, yet the molecular mechanisms underlying their analgesic effects remain unclear. Here, we identified a novel Kunitz-type peptide, sibanin, from Simulium bannaense venom, which exhibits both potent analgesic and anticoagulant properties. Using pain activity tracking, HPLC, and electrophysiological techniques, we found that sibanin potently inhibited the Na_V1.7 channel (IC₅₀: 265.03 ± 7.86 nM), selectively reducing pain signal transmission in mouse thermal pain models. Mutagenesis studies identified critical residues (N209 and A1585) in the Na_V1.7 voltage-sensing domain (S3b-S4a) essential for sibanin binding, conserved across vertebrate hosts. Concurrently, sibanin inhibited coagulation factors (e.g., FXa) and proteases, preventing thrombus formation. This dual functionality enables black flies to suppress host pain perception and ensure continuous blood flow during feeding. The unique synergy of Na_V1.7-targeted analgesia and anticoagulation highlights sibanin's potential as a lead compound for dual-action therapeutics in pain management and thrombotic disease treatment, circumventing polypharmacy risks. Our findings elucidate a conserved evolutionary strategy in hematophagous insects and provide a foundation for developing multifunctional pharmacological agents.