Enveloped viruses exploit the endomembrane system to enter host cells. Through a cascade of membrane-trafficking events, virus-bearing vesicles fuse with acidic endosomes and/or lysosomes mediated by SNAREs triggering viral fusion. However, the molecular mechanisms underlying this process remain elusive. Here, we found that UV-radiation resistance-associated gene (UVRAG), an autophagic tumor suppressor, is required for the entry of the prototypic negative-strand RNA virus, including influenza A virus and vesicular stomatitis virus, by a mechanism independent of IFN and autophagy. UVRAG mediates viral endocytic transport and membrane penetration through interactions with the class C vacuolar protein sorting (C-Vps) tethering complex and endosomal glutamine-containing SNAREs [syntaxin 7 (STX7), STX8, and vesicle transport through t-SNARE homolog 1B (Vti1b)], leading to the assembly of a fusogenic trans-SNARE complex involving vesicle-associated membrane protein (VAMP8), but not VAMP7. Indeed, UVRAG stimulates VAMP8 translocation to virus-bearing endosomes. Inhibition of VAMP8, but not VAMP7, significantly reduces viral entry. Our data indicate that UVRAG, in concert with C-Vps, regulates viral entry by assembling a specific fusogenic SNARE complex. Thus, UVRAG governs downstream viral entry, highlighting an important pathway capable of potential antiviral therapeutics.
Keywords: VSV; endocytic trafficking; influenza virus.