The role of LGP2 in antiviral immunity is controversial. Both positive and negative effects on RIG-I- and MDA5-mediated type I IFN signaling have been reported in response to different viruses [15, 21–24]. One study shows that LGP2 is not essential for the induction of innate immune response, but rather is required for controlling antigen-specific CD8-positive T cell survival in response to virus infection . However, several studies suggest that LGP2 works upstream of RIG-I and MDA5 to potentiate viral RNA-induced signaling and is essential for RIG-I- and MDA5-mediated type I IFN signaling and antiviral immunity [21, 54]. In particular, LGP2 recognizes L region of EMCV genome and promotes the type-I interferon signal in response to EMCV infection . Our results indicate that both LGP2 and DHX29 could markedly affect MDA5-mediated type I IFN response to HMW poly(I:C). Co-expression of LGP2 and DHX29 increases MDA5-mediated type I IFN signaling more than those obtained with either LGP2 or DHX29 expression alone. Ectopic expression of DHX29 can partially rescue HMW poly(I:C)-induced type I IFN signaling reduced by LGP2 KD. Thus, our study suggests that DHX29 positively regulate MDA5-mediated type I IFN signaling independent of LGP2. Consistent with this notion, we show that DHX29 does not interact with LGP2. Thus, our results identify a previously unrecognized role of DHX29 in MDA5-mediated type I IFN signaling and anti-EMCV immunity. Another MDA5 activator PACT was reported to promote MDA5 signaling by promoting MDA5 oligomerization , it will be of interest to investigate the relationship between DHX29 and PACT in the near future studies.