Cloning, expression and purification of AsSGU protein and its immunogenic response analysis as target candidate for transmission blocking vaccine against malaria.

AsSGU (Anopheles stephensi Secretory Glycoconjugate of Unknown function) is a GPI-anchored (Glycosyl-phosphatidyl-inositol) protein that is expressed in An. stephensi midgut after blood feeding. The role of midgut specific SGU protein in ookinetes invasion and transmission-blocking activity of the Plasmodium parasite has been confirmed and reported in An. sgambiae. It is a highly conserved protein in mosquito species Anopheles, Culex, and Aedes. It has critical role in ookinetes invasion; hence AsSGU protein is investigated for its biological functions in An. stephensi. The assgu gene expression was analysed at different time interval after blood feeding. In-silico analysis of assgu gene confirms its immunogenic nature. The target gene is cloned and transformed in E. coli BL21 (DE3) host and recombinant protein was isolated and purified. The expressed recombinant protein was found to be secretary in nature, 0.2 mg/L of recombinant protein was isolated from bacterial culture. The recombinant protein was injected in rabbit for immunological response analysis.