Inhibition of mosquito salivary gland apyrase activity by antibodies produced in mice immunized by bites of Anopheles stephensi mosquitoes.

Mice (BALB/c) were immunized to mosquito saliva by repeated bites of Anopheles stephensi mosquitoes. Studies were conducted on the ability of these mice to develop antibodies against the apyrase component of the saliva. By means of immunoprecipitation procedures and Western blot analysis, we demonstrated the presence of antiapyrase antibodies to the mosquito saliva. Furthermore, these antibodies were able to inhibit apyrase activity. Serum titers of 1:20 were able to inhibit approximately 90% of salivary gland apyrase activity, while titers of 1:160 retained the ability to inhibit more than 50% of apyrase activity. Parallel inhibition assays with immunoglobulin G (IgG) from immunized versus nonimmunized mice showed that the inhibitory activity of serum from immunized mice could be accounted for by its IgG component. Mosquito salivary gland apyrase has previously been shown to facilitate mosquito feeding by inhibiting aggregation of platelets at the mosquito bite site. However, our studies have shown that mosquitoes feeding on immunized mice had no deficiency in probing these mice for a blood meal, even in the face of high titers of anti-apyrase antibodies.