Plasmodium infection-induced changes in salivary gland proteins of malaria vector Anopheles stephensi (Diptera:Culicidae).

Parasitism by Plasmodium yoelii yoelii induced 18 polypeptides in the salivary glands of aging malaria vector Anopheles stephensi. A polypeptide of low molecular size (30 kDa) could generally be induced at all infected stages. On day 5 post blood feeding (PBF), no new polypeptide could be found in the salivary glands. Seven polypeptides of low molecular size and 3 of high molecular size could be induced on day 11 PBF, which inducibility coincided with the invasion of the salivary glands by the sporozoites. Quantitatively, soluble proteins decreased in the salivary glands by about one-third in females that had consumed infected or uninfected blood meal on day 9 (oocysts stage) as compared to nonfeeding females. However, on day 15, in the salivary glands invaded by sporozoites, the amount of proteins obtained from infected females was approximately 26% lower than that obtained from uninfected females. A similar reduction was also observed in aged (20 days PBF) salivary glands of infected mosquitoes. These proteins could confer parasite tolerance to the females and enhance parasite transmission potential.