The molecular basis of adaption of aedes mosquitoes, vectors of viral diseases, to saltwater environments

Vector-borne diseases constitute an enormous health burden, particularly in tropical and sub-tropical regions. Mosquitoes of the genus Aedes transmit the viruses responsible for yellow fever, Dengue, Zika and Chikungunya. Dengue is rapidly reaching pandemic proportions and currently constitutes a major health problem in Sri Lanka. At the same time, cases of Chikungunya are increasing. In the absence of vaccines or drugs for these diseases, vector control is the only means of limiting their spread. Like many other mosquitoes, Aedes species breed in stagnant fresh water. A surprising recent finding is that Aedes mosquitoes in Sri Lanka have adapted to breed in brackish water as well, thereby extending the area where transmission of Dengue virus can occur. The aim of this collaborative grant is to elucidate the physiological and molecular basis of adaptation using next generation sequencing (RNA-seq) and immuno-electron microscopy. The project also contains two training components - a workshop to teach bioinformatics to students in Sri Lanka and two three-month stays in Swiss laboratories for Sri Lankan PhD students to learn recombinant protein technology and electron microscopy. Wells with brackish water are common in households on the Jaffna Peninsula in northern Sri Lanka and may have contributed to selection of Aedes mosquitoes that are tolerant to salinity. At present, national and international dengue control guidelines target only fresh water breeding sites. This knowledge gain is expected to help control dengue transmission. Furthermore, understanding the basis of adaptation has wider implications for the spread of other mosquito-borne diseases, including malaria and West Nile virus, which are transmitted by other species of mosquitoes.