RNA interference screen for human genes associated with West Nile virus infection

West Nile virus: interaction with human cells This manuscript reports a comprehensive systems level description of the molecular signatures governing the interaction of West Nile virus with human cells. A whole-genome human RNA interference gene silencing screen in HeLa cells identified 305 host proteins genes that facilitate West Nile virus infection of human cells. A number of the identified also play a role in the infection of dengue virus, another flavivirus related to West Nile virus. This work highlights differences in the molecular pathogenesis of related flaviviruses, and points to several possible new targets for antiviral drugs Genome-wide RNAi screen in human cells identifies host factors that regulate replication of the West Nile virus. Some of these factors are shown to relevant for dengue virus as well. West Nile virus (WNV), and related flaviviruses such as tick-borne encephalitis, Japanese encephalitis, yellow fever and dengue viruses, constitute a significant global human health problem 1 . However, our understanding of the molecular interaction of such flaviviruses with mammalian host cells is limited 1 . WNV encodes only 10 proteins, implying that it may use many cellular proteins for infection 1 . WNV enters the cytoplasm through pH-dependent endocytosis, undergoes cycles of translation and replication, assembles progeny virions in association with endoplasmic reticulum, and exits along the secretory pathway 1 , 2 , 3 . RNA interference (RNAi) presents a powerful forward genetics approach to dissect virus–host cell interactions 4 , 5 , 6 . Here we report the identification of 305 host proteins that affect WNV infection, using a human-genome-wide RNAi screen. Functional clustering of the genes revealed a complex dependence of this virus on host cell physiology, requiring a wide variety of molecules and cellular pathways for successful infection. We further demonstrate a requirement for the ubiquitin ligase CBLL1 in WNV internalization, a post-entry role for the endoplasmic-reticulum-associated degradation pathway in viral infection, and the monocarboxylic acid transporter MCT4 as a viral replication resistance factor. By extending this study to dengue virus, we show that flaviviruses have both overlapping and unique interaction strategies with host cells. This study provides a comprehensive molecular portrait of WNV–human cell interactions that forms a model for understanding single plus-stranded RNA virus infection, and reveals potentia