Identification and molecular analysis of mid-gut mucin gene in Anopheles stephensi (Diptera: Culicidae)

Recognition of Anopheles mid-gut molecules interacting with the malaria parasite is important as they can potentially be targeted to interrupt the life cycle of the parasite in the mosquito's body. The mid-gut of mosquitoes is covered with the glycocalyx, which is composed of various glycoproteins. Pieces of evidence show that mucin proteins are one of the most frequent ingredients of the glycocalyx. In the present study, we isolated and identified the sequence of mucin from the mid-gut of Anopheles stephensi, Liston and Kazerun strains. Anopheles stephensi mucin (AsMuc) has two central core repeats with the consensus sequence TTTTVAP flanked with a hydrophobic N-terminus and a C-terminus which it seems are both necessary for cell surface expression. To show if this molecule is expressed on the surface of the cell, we cloned AsMuc in a baculovirus vector and tracked the expression of the protein in Sf9 insect cells. Immune assays showed the surface localization of the recombinant mucin. AsMuc expression on the surface of the cell suggests it could be a potential ligand for Plasmodium spp. attachment to the Anopheles mid-gut.