Development of vector-specific, resistance-breaking insecticides to reduce malari

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DESCRIPTION (provided by applicant): Malaria exacts a terrible toll in sub-Saharan Africa, killing an estimated 1-2 million persons each year, mostly children. Pyrethroid-based insecticide treated nets (pyrethroid ITNs) provide the first line of defense against disease transmission, but emerging resistant strains of the disease vector (Anopheles gambiae) threaten to render these ITNs ineffective. Our broad objective is to develop a new class of acetylcholinesterase (AChE)-targeting insecticide for deployment on ITNs, that is safe for use, effective against current pyrethroid- and AChE- resistant strains, and is less likely to foster emergence of new AChE-resistant strains. Thus our goal is consistent with the focus of the solicitation on novel interventions for the control of Malaria. FNIH-sponsored research from 2005-2008 enabled us to make significant progress towards our long-term goal. Further support from NIH will allow us to establish proof of concept that our novel AChE-based insecticide, deployed on an ITN, would constitute a superior intervention to manage the disease vector. Thus our goal is also consistent with the stated aim of the solicitation to fund translational research. To achieve our goal we have assembled a team of chemists, structural biologists, entomologists, and toxicologists. Our specific aims are to 1)improve stability of An. gambiae AChE (AgAChE)-selective carbamates to oxidative detoxification; 2)acquire 3D structural information on AgAChE to optimize inhibition potency and selectivity; 3)develop bivalent carbamates for resilience to target-site mutation; 4)identify strategies to mitigate against carboxylesterase-mediated detoxification; and 5)make a preliminary assessment of mammalian toxicity of the most promising insecticides to emerge from these studies. To guide us through the proposed five years of research we have prepared a detailed timeline and decision tree that incorporate five integrated streams of insecticide discovery for optimizing field performance and human safety. Moreover the built-in complementarity of the chemical synthesis routes and the optimization approaches (e.g. resilience to both target-site and metabolic resistance mechanisms) means that unexpected difficulty in one stream need not slow progress in the other streams. These multiple approaches increase the probability of project success. Malaria exacts a terrible toll in sub-Saharan African, and at present the first line of defense against the mosquito vector of the disease is provided by insecticide treated nets (ITNs). However, growing resistance to the class of insecticide used on the nets threatens to make this protection ineffective. We propose to develop a new class of insecticide that is safe for ITN deployment, effective against current insecticide-resistant mosquitoes, and less likely to promote emergence of new resistant strains.