Redox-dependent formation of a viral amyloid and functional impact

Abstract

AbstractThe Hendra and Nipah viruses (HeV and NiV) are zoonotic biosafety level-4 pathogens within theParamyxoviridaefamily. We previously showed that their W proteins form amyloid-like fibrilsin vitro. Here, we demonstrate that W also forms fibrilsin cellulaand that cysteine residues are crucial in dictating the ability of W proteins to fibrillate. The cysteine oxidation state acts as a switch to generate either amorphous aggregates or flexible fibrils. Ectopic expression of WHeVinduces an oxidative stress and WHeVfibrils were observed in the nuclei of different cell lines, with fibrillation being impaired by cysteine substitutions. Finally, nuclear fibrils are associated with an impairment of the NF-κB pathway in WHeVtransfected cells. This work provides experimental evidence for the ability ofHenipavirusW proteins to fibrillate in transfected cells and the first clues on their functional impact.Significance StatementNipah and Hendra viruses are severe pathogens infecting humans and livestock, classified among the 8 highest priorities for research by the WHO. The W protein, along with the V protein, is a virulence factor responsible for antiviral response inhibition and we demonstrate here that its fibrillation into amyloid-like fibrils occurs in the nucleus of transfected cells, with their formation being dependent of the redox state of the W cysteine residues. The sole transfection of W provokes the production of reactive oxygen species, creating a suitable environment for the fibrils to form. Finally, we show that W fibrils enhance the repression of the antiviral response, thus pointing to W fibrillation as a new promising antiviral target.