Cleavage of TNF receptor-associated factors 3 (TRAF3) by Enterovirus 71 3C protease

Objective To clarify whether Enterovirus 71 3C protease,a key player in immunity evasion in EV71 infection,can cleave TNF receptor-associated factor 3 (TRAF3).Methods Western blot was used to explore the TRAF3 expression in EV71-infected cells.Plasmids expressing TRAF3 and 3C were then cotransfected into cells to detect whether 3C induces TRAF3 cleavage.A mutational analysis was carried out to explore the sites in TRAF3 for 3C cleavage.The effect of 3C on the interaction between TRAF3 and TRIF was analyzed by immunoprecipitation analysis.Results The TRAF3 expression was reduced by EV71 infection,and 3C induced the cleavage of TRAF3.The cleavage depended on 3C protease activity.The Q242-G243 is the cleavage site of 3C in TRAF3.3C also impeded the interaction between TRAF3 and TRIF.Conclusions 3C induces TRAF3 cleavage in a protease activity dependent manner,which may in turn antagonizes innate immunity. Key words: Entervirus 71 ;  TNF receptor-associated factors 3;  3C protease;  Innate immunity