Ebolaviruses: New roles for old proteins
VP35 inhibits the type-I IFN response through several different mechanisms. VP35 can bind to dsRNA, preventing the activation of RIG-I signalling. In addition, VP35 blockade of IRF3 and IRF7 phosphorylation inhibits the production of IFN-β. Recent studies have also highlighted the importance of VP35 in regulating NP–RNA association. During viral genome replication, the VP35 N-terminal peptide binds to NP, enabling the vRNA to associate with the RdRp complex for replication. During virus assembly, VP35 disassociates, enabling NP to oligomerise, bind RNA, and form the nucleocapsid. 5’PPP, 5’ triphosphate; dsRNA, double-stranded RNA; IFN, interferon; IKK, inhibitor of nuclear factor kappa B kinase subunit epsilon; IRF, interferon regulatory factor; MAVS, mitochondrial antiviral-signalling protein; MDA5, melanoma differentiation-associated protein 5; NP, nucleoprotein; PACT, protein activator of the interferon-induced protein kinase; RdRp, RNA-dependent RNA polymerase; RIG-I, retinoic acid-inducible gene I; TANK, tumour necrosis factor–receptor-associated factor family member–associated nuclear factor kappa B activator; TBK1, tumour necrosis factor–receptor-associated factor family member–associated nuclear factor kappa B activator binding kinase 1; TRAF3, tumour necrosis factor–receptor-associated factor 3; VP, viral protein; vRNA, viral RNA.