PPRV-V, -P and -C protein antagonism of IFN induction and response pathways. PPRV-V, -P and C protein can interfere with IFN signaling activity. Full lines indicate blocking effects reported for PPRV proteins, and dotted lines indicate blocking activity for other Morbillivirus proteins. A) V and C proteins interfere with IFN production. Viral motifs (e.g. double stranded RNA) can be recognized by pattern recognition receptors (PPRs). This leads to IRF3, IRF7 and NF-κB activation, which in turn promotes IFN-β induction. Morbillivirus C protein can impair IRF3 binding to the IFN-β promoter in the nucleus. Morbillivirus C protein can also limit viral replication and consequently limit the amount of viral motifs recognisable for PRRs. PPRV-V protein blocks IFN-β promoter activity, although the mechanism has yet to be elucidated. Morbillivirus V proteins can bind and block RIG-I and MDA5 activity. Morbillivirus V proteins can also suppress NF-κB activity and interacts with IKKα to block IRF7 activation. B) PPRV-V protein can block Tyk2 phosphorylation and block STAT1 and STAT2 activation, and thus impairs type I and III IFN responses. C) PPRV-V blockade of STAT1 also antagonizes type II IFN responses. Other Morbilliruses V protein can also block STAT3 activation, which can be involved in type II IFN responses and in transition from innate to adaptive immunity. PPRV-P protein can also inhibit type I and II IFN responses although to a lesser extent than PPRV-V protein.