Anopheles stephensi Dual Oxidase Silencing Activates the Thioester-Containing Protein 1 Pathway to Suppress Plasmodium Development

We characterized the dual oxidase (Duox) gene in the major Indian malaria vector Anopheles stephensi, which regulates the generation of reactive oxygen species. The AsDuox gene encodes for a 1,475-amino-acid transmembrane protein that contains an N-terminal noncytoplasmic heme peroxidase domain, a calcium-binding domain, seven transmembrane domains, and a C-terminal cytoplasmic NADPH domain. Phylogenetic analyses revealed that A. stephensi Duox protein is highly conserved and shares 97–100% amino acid identity with other anopheline Duoxes. AsDuox is expressed in all the developmental stages of A. stephensi and the pupal stages revealed relatively higher expressions. The Duox gene is induced in Plasmodium-infected mosquito midguts, and RNA interference-mediated silencing of this gene suppressed parasite development through activation of the thioester-containing protein 1 pathway. We propose that this highly conserved anopheline Duox, being a Plasmodium agonist, is an excellent target to control malaria parasite development inside the insect host.