As obligatory parasites viruses need cellular resources. Our aim is to identify cellular factors that are needed for, or that restrict, virus infection. We study different human pathogens, including viruses that cause respiratory infections in childrens, mosquito-delivered tropical viruses that can cause lethal encephalitis, and viruses that represent model systems for diseases such as rabies and lethal haemorrhagic fever. The starting point of our research are genome-size gentetic screens that provide us with a list of cellular proteins that play key roles in the infection proces of each virus. To understand their mechanism of action, we take advantage of biochemical, cell biological and advanced imaging techniques, from high-content fluorescence imaging to single-molecule resolution live cell microscopy.