Inhibition of Anopheles gambiae Odorant Receptor Function by Mosquito Repellents [Signal Transduction]

February 5th, 2015 by Tsitoura, P., Koussis, K., Iatrou, K.

The identification of molecular targets of insect repellents has been a challenging task, with their effects on odorant receptors (ORs) remaining a debatable issue. Here, we describe a study on the effects of selected mosquito repellents including the widely used repellent DEET, on the function of specific ORs of the African malaria vector Anopheles gambiae. The study, which has been based on quantitative measurements of a Ca2+-activated photoprotein biosensor of recombinant OR function in an insect cell-based expression platform and a sequential compound addition protocol, revealed that heteromeric OR (ORx/Orco) function was susceptible to strong inhibition by all tested mosquito repellents except DEET. Moreover, our results demonstrated that the observed inhibition was due to efficient blocking of Orco function. This mechanism of repellent action, which is reported for the first time, is distinct from the mode of action of other characterized insect repellents including DEET.