Simukunin from the salivary glands of the black fly Simulium vittatum inhibits enzymes that regulate clotting and inflammatory responses

Black flies (Diptera: Simuliidae) feed on blood, and are important vectors of Onchocerca volvulus, the etiolytic agent of River Blindness. Blood feeding depends on pharmacological properties of saliva, including anticoagulation, but the molecules responsible for this activity have not been well characterized. Methodology/principal findings: Two Kunitz family proteins, SV-66 and SV-170, were identified in the sialome of the black fly Simulium vittatum. As Kunitz proteins are inhibitors of serine proteases, we hypothesized that SV-66 and/or -170 were involved in the anticoagulant activity of black fly saliva. Our

We conclude that Simukunin preferentially inhibits Factor Xa. The inhibition of elastase and cathepsin G further suggests this protein may modulate inflammation, which could potentially affect pathogen transmission.