Dengue fever is one of the most prominent viral infectious diseases in tropical countries. The virus is transmitted by the mosquito Aedes aegypti, infecting over 300 million people each year. To understand how this mosquito is such an efficient vector, this research uses genetic tools to reveal what happens when a mosquito is infected by the virus and how a bacterium called Wolbachia might interfere with virus infection. This thesis has discovered new aspects about mosquito biology that could lead to improved disease surveillance and understanding of dengue virus evolution.