Malaria is transmitted by the bite of the female Anopheles mosquitoes that are infected with Plasmodium parasites. This disease kills almost a million people each year, mostly pregnant women and young children in Africa. In 2012 there were 200 million people infected with malaria, and 3.3 billion people were at risk of infection. In the absence of an effective malaria vaccine, chemical control of the mosquito vector through the use of insecticides remains the best weapon to fight malaria transmission. Insecticide resistance in mosquitoes is however on the rise, and novel methods to control mosquito populations are urgently needed. As an alternative tool for malaria control, the use of Wolbachia endosymbionts has been widely proposed as these bacterial infections are able to spread rapidly through insect populations and render hosts resistant to co-infections with disease-causing pathogens, including Plasmodium. Previous efforts to find these bacteria in Anopheles species were unsuccessful, however we recently discovered a novel Wolbachia strain, which we called wAnga, in natural populations of several species of Anopheles mosquitoes in Burkina Faso, West Africa. In this project we will considerably expand our knowledge of this natural Wolbachia infection in Anopheles mosquitoes, and will generate a formidable toolkit for future studies aimed at assessing the use of these bacteria for malaria control. We will culture wAnga in cell lines and we will sequence the bacterial genome. We will generate stably infected mosquito lines and will test key reproductive phenotypes potentially induced by Wolbachia. Moreover, we will develop a rapid and specific method to facilitate detection of infected mosquitoes in field settings that will be instrumental to study the prevalence and distribution of infection in field mosquito populations. This highly innovative proposal will open up a new area of research and offers an exceptional opportunity to further endosymbiont-based vector control methods for Anopheles species.

Public Health Relevance

Mosquito control is an essential component of strategies aimed at stopping the spread of malaria. We propose to fully characterize a recently discovered bacterial infection of Anopheles called Wolbachia, which has the potential to spread in field populations and to reduce vector competence for malaria. This knowledge will aid the validation and implementation of novel strategies to stop malaria transmission based on the use of Wolbachia.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Exploratory/Developmental Grants (R21)
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Special Emphasis Panel (ZRG1-IDM-M (02))
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Costero-Saint Denis, Adriana
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Harvard University
Schools of Public Health
United States
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Shaw, W Robert; Marcenac, Perrine; Childs, Lauren M et al. (2016) Wolbachia infections in natural Anopheles populations affect egg laying and negatively correlate with Plasmodium development. Nat Commun 7:11772
Shaw-Saliba, Kathryn; Clarke, David; Santos, Jorge M et al. (2016) Infection of laboratory colonies of Anopheles mosquitoes with Plasmodium vivax from cryopreserved clinical isolates. Int J Parasitol 46:679-83
Shaw, W Robert; Attardo, Geoffrey M; Aksoy, Serap et al. (2015) A comparative analysis of reproductive biology of insect vectors of human disease. Curr Opin Insect Sci 10:142-148