Biological Control of Dengueʼs Mosquito Vector

Abstract

Dengue virus has reemerged in the past thirty years, with an expanded geographic distribution and increased epidemic activity, as well as the emergence of the more severe hemorrhagic fever in new locations. It is now the most important arboviral disease of humans in terms of both morbidity and mortality, and a lack of an effective vaccine or treatment for the disease makes control of its mosquito vectors a consideration of primary importance [1]. With insecticide resistance and previous ineffective deployment of longlasting mosquito control programs, contemporary approaches include the use of modern DNA technology to genetically modify mosquitoes and reduce their disease transmission capacity [2]. Another promising new venue and the focus of this thesis is the recent proposition of utilizing Wolbachia, an obligate endosymbiotic bacteria thought to infect around 70% of the world’s insect species and capable of rapidly establishing in host populations. Certain strains of Wolbachia have been shown to confer pathogen resistance to its hosts, providing a mechanism of limiting dengue replication and transmission by the mosquito vector [3]. This thesis provides a case study of a vector competence experiment performed at the Oxford University Clinical Research Unit in Ho Chi Minh City, Vietnam, probing whether two different strains of Wolbachia induce resistance to dengue virus in an Indonesian strain of A. aegypti. The positive results allowed for the ongoing (early 2014) field release of Wolbachia-infected mosquitoes in two suburbs of Yogyakarta, Indonesia by the Eliminate Dengue Project, a non-profit international collaboration. Field releases in dengue endemic settings will provide information on Wolbachia’s potential to establish in local mosquito populations and to limit the transmission of dengue virus.