Japanese Encephalitis Virus infection induces inflammation of swine testis through RIG-I-NF-ĸB signaling pathway.

Japanese Encephalitis Virus (JEV) is an important zoonotic flavivirus transmitted by mosquitos. JEV infection in sows primarily manifests as a reproductive disease such as abortion and transient infertility while in infected boars, it can cause orchitis. Previous studies mainly focused on the pathogenesis of human encephalitis caused by JEV infection, while few concentrations have been made to unveil the potential mechanism of reproductive dysfunction in JEV-infected pigs. In this study, histopathological analysis and immunohistochemistry staining was performed on testis of JEV-infected boars, indicating that JEV could infect testicular cells and cause inflammatory changes in testis. In vitro assays reveal that primary swine testicular cells and swine testis (ST) cells are highly permissive to JEV and significant inflammatory response was shown during JEV infection. Mechanically, we found that JEV infection increases the expression of retinoic acid-inducible gene I (RIG-I) and activates transcription factor NF-κB. Production of pro-inflammatory cytokines was greatly reduced in JEV infected testicular cells after knockout of RIG-I or treatment with the NF-κB specific inhibitor. In addition, activation of NF-κB was also significantly suppressed upon RIG-I knockout. Taken together, our results reveal that JEV could infect boar testicles, and RIG-I-NF-κB signaling pathway is involved in JEV-induced inflammation in swine testicular cells.