Final Report Summary - VIRNA (Cellular biology of virus infection)
The early steps in animal virus infection were analyzed using a combination of high throughput screening by siRNA silencing and a broad spectrum of cell biological techniques including high-end light microscopy and molecular biology. The viruses analyzed included members of 6 different virus families (polyoma, alpha, pox, herpes, bunya, paramyxo, and myxoviruses). The screens ranged in size between large genome-wide and small targeted screens. The results provided a detailed picture of the strategies and diverse molecular mechanisms that enveloped and non enveloped viruses use to enter cells in tissue culture. Aside from different modes of endocytosis, the molecular data emphasized the priming of viruses prior to penetration and the subsequent uncoating processes. The screens and the follow-up validations allowed the identifiction of thousands cellular proteins and processes required to provide assistance for the incoming viruses during entry and uncoating as well as the identification of numerous genes involved in suppressing virus infection. This information provided major insights into the intercations between the incoming viruses and complex cellular machinery for cell surface dynamics, signaling, endocytosis, endosome maturation, RNA and protein degradation, nuclear import, cell division, and other processes. In addition, the screening was used to identify viral genes involved in early intracellular events such as uncoating and initiation of transcription and replication. In this way, the project has helped to illuminate one of the least understood steps in the viral replication cycle, and tp provide deep insights for the development of new antiviral strategies.