Toll-like receptors (TLRs) mediate immune responses via the recognition of pathogen-associated molecular patterns (PAMPs), thus playing important roles in host defense. Among the chicken (Ch) TLR family, ChTLR3 and 7 have been shown to recognize viral RNA. In our earlier studies, we have reported polymorphisms of TLR1, 2, 4, 5, 15 and 21. In the present study, we amplified TLR3 and 7 genes from different chicken breeds and analyzed their sequences. We identified 7 amino acid polymorphism sites in ChTLR3 with 6 outer part sites and 1 inner part site, and 4 amino acid polymorphism sites in ChTLR7 with 3 outer part sites and 1 inner part site. These results demonstrate that ChTLR genes are polymorphic among different chicken breeds, suggesting a varied resistance across numerous chicken breeds. This information might help improve chicken health by breeding and vaccination.

Toll-like receptors (TLR) mediate immune responses via the recognition of pathogen-associated molecular patterns, thus playing important roles in hos

Japanese encephalitis virus (JEV) is the causative agent of Japanese encephalitis, which poses great threats to the pig farming industry and human health. To establish infection, JEV has evolved sophisticated strategies to overcome the innate immune responses and finish its life cycle. Previous studies have shown that non-structural protein 1 (NS1) is closely related to its pathogenesis, while its molecular mechanism remains elusive. In this study, host protein ATP-dependent RNA helicase DEAD-box helicase 3 X (DDX3X) was screened to bind with NS1, and both ectopically expressed and virally encoded NS1 further confirmed their interaction. We also proved that the β-roll and wing subdomains of NS1 were responsible for their interaction. In DDX3X-overexpressing cells, the replication of JEV was markedly inhibited, while the viral titers were elevated in DDX3X-silencing cells, indicating that DDX3X might serve as an anti-viral factor during JEV infection. Mechanically, overexpression of DDX3X promotes interferon-beta (IFN-β) transcription, while its transcription was decreased in DDX3X-silencing cells. Consistent with IFN-β, some interferon-stimulated genes (ISGs), including protein kinase R (PKR), myxovirus resistance 1 (MX1), guanylate-binding protein 1 (GBP1), and bone marrow stromal antigen 2 (BST2), were also positively related to the DDX3X expression. Taken together, JEV NS1 blocks IFN-β production by interacting with DDX3X to evade the host’s innate immune response and facilitate virus replication. This finding will deepen our understanding of JEV immune-evasion strategies and provide targets for JEV attenuation. IMPORTANCE: This study focused on JEV, a threat to pig farming and human health. The key finding is that NS1 binds to host protein DDX3X via its β-roll and wing subdomains. JEV NS1 evades the host immune response by interacting with DDX3X to restrain type I interferon production. These results deepen our understanding of JEV’s immune-evasion strategies and offer potential targets for JEV attenuation.