Abstract
Flaviviruses are RNA viruses that cause serious diseases in humans, with currently no antivirals available. Targeting host factors is emerging as an attractive antiviral approach, but first we need to understand basics of which host proteins are hijacked and why. Here, using a combination of fluorescence microscopy, knock-down, crosslinking immunoprecipitation sequencing, mass spectrometry, and biophysical assays, we identify nucleoporin-153 (NUP153) as a proviral factor during flavivirus infection. We show that NUP153 is recruited to the virus amplification site on the endoplasmic reticulum and needed early on during infection. We find that NUP153 interacts with the viral proteins NS3 and NS5, and a highly conserved G-rich motif on the viral RNA. The interactions promote the production of viral structural proteins, leading to an efficient virion assembly, virus release and spread to new cells. Importantly, we identifyNUP153 as a key regulator in viral polyprotein translation, a mechanism that appears conserved among flaviviruses.