Dissecting the molecular mechanisms of olfaction in a malaria-vector mosquito.

Abstract

Human malaria is widely endemic in tropical and subtropical regions of the world, where ca. 1.5 billion people are at risk, ca. 500 million clinical cases occur, and 1–3 million deaths, mostly of children, are due wholly or in part to the disease (see, e.g., http://www.malaria.org/). All of the species of Plasmodium that infect humans and cause malaria are transmitted by mosquitoes of the genus Anopheles. The African malaria mosquito, Anopheles gambiae, is especially dangerous owing to its dramatic tendency to feed on humans (anthropophily) and resulting extraordinary efficiency as a vector of the most deadly of the parasites, Plasmodium falciparum (1). In mosquitoes, host-seeking and selection are mediated by volatile chemicals emanating from the host (2). Thus, the likelihood that the anthropophily and high vectorial capacity of A. gambiae are based on olfactory cues has stimulated interest in mosquito olfaction. Two papers published in PNAS (including one in this issue) begin to dissect the molecular mechanisms that mediate olfactory sensory transduction in the antennae of A. gambiae. The recent paper by Fox et al. (3) describes the identification and characterization of a family of G-protein-coupled receptors (GPCRs) that are thought to be the first identified mosquito odorant receptors (ORs). The paper by Merrill et al. in this issue (4) documents the cloning and characterization of an arrestin involved in the regulation of the olfactory response in A. gambiae.