Aedes mosquitoes are the main vectors of dengue virus (DENV) and other arboviruses, including Zika virus (ZIKV), for which neither vaccine nor antiviral treatment is currently available. Understanding the factors that influence the transmission of arboviruses from mosquitoes to humans is therefore a priority because it could guide the implementation of public health measures that could limit or even prevent epidemics. In a study published on January 5, 2023 in the journal Nature Microbiology (https://pubmed.ncbi.nlm.nih.gov/36604511/), researchers from the team of Joao Marques at the Institute of Molecular and Cellular Biology in Strasbourg (CNRS UPR9022-ERL INSERM U1257) and at the Federal University of Minas Gerais in Belo Horizonte, Brazil, describe the collection of viruses (the virome) present in 800 mosquitoes collected in 6 countries and 4 continents. They identify 12 insect-specific viruses and show that two of them increase the multiplication of dengue and Zika viruses and their transmission to mammals. The mechanism involved reveals a new cellular factor hijacked by arboviruses in mosquitoes.