Midgut specific immune response of vector mosquito Anopheles stephensi to malaria parasite Plasmodium.

Innate immune-related polypeptides expression in midgut in the ageing vector mosquito A. stephensi following infection by malaria parasite, Plasmodium yoelii yoelii has been studied. Twenty polypeptides were induced by an infected blood meal during various stages of adult life. A 24 kDa polypeptide was induced generally in most of the stages. Maximum parasite induced polypeptides i.e. 22, 33, 111, 122, 127, 140, 143 and 146 kDa were found in 5 days of post blood feeding (PBF) which coincides with the presence of oocysts on the midgut. However, in addition, three polypeptides in 11 days PBF and 8 polypeptides in 20 days PBF were also induced due to parasite infection in aged mosquitoes. Quantitatively, the amount of soluble proteins in the midgut in oocyst-sporozoite-positive mosquitoes was always less as compared to their normal counterparts. The parasite evidently elicits defined immune responses by inducing specific polypeptides in the midgut of the mosquito.

Heat shock response during development of the malaria vector Anopheles stephensi (Culicidae: Diptera).

The pattern of synthesis of heat shock proteins (HSP) and thermotolerance to elevated temperatures during the development of the malaria vector Anopheles stephensi normally reared at 28 +/- 2 degrees C was studied using SDS-PAGE. In total twelve heat shock proteins (i.e. 31, 33, 38, 43, 44, 51, 57, 62, 69, 71, 113 and 121 kD were induced by heat shock during various stages of development. Eight polypeptides (HSP during one or other of the instars) appeared during normal development of the adult, which showed very little response towards heat shock. Only two polypeptides (57 and 69 kD) were induced while the 22.5 kD protein disappeared during adult life. The HSP 62 and 71 kD induced during the larval stages showed a sharp decline in quantity in male and female adults upon heat shock. Three HSP (31, 43 and 44 kD) were induced in pupae due to heat shock. The synthesis of HSP in A. stephensi was correlated with the various morphological and physiological events occurring during development.

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.