FoxJ1 inhibits African swine fever virus replication and viral S273R protein decreases the expression of FoxJ1 to impair its antiviral effect.

African swine fever (ASF) is a highly pathogenic swine infectious disease that affects domestic pigs and wild boar, which is caused by the African swine fever virus (ASFV). ASF has caused huge economic losses to the pig industry and seriously threatens global food security and livestock health. To date, there is no safe and effective commercial vaccine against ASF. Unveiling the underlying mechanisms of ASFV-host interplay is critical for developing effective vaccines and drugs against ASFV. In the present study, RNA-sequencing, RT-qPCR and Western blotting analysis revealed that the transcriptional and protein levels of the host factor FoxJ1 were significantly down-regulated in primary porcine alveolar macrophages (PAMs) infected by ASFV. RT-qPCR analysis showed that overexpression of FoxJ1 upregulated the transcription of type I interferon and interferon stimulating genes (ISGs) induced by poly(dA:dT). FoxJ1 revealed a function to positively regulate innate immune response, therefore, suppressing the replication of ASFV. In addition, Western blotting analysis indicated that FoxJ1 degraded ASFV MGF505-2R and E165R proteins through autophagy pathway. Meanwhile, RT-qPCR and Western blotting analysis showed that ASFV S273R inhibited the expression of FoxJ1. Altogether, we determined that FoxJ1 plays an antiviral role against ASFV replication, and ASFV protein impairs FoxJ1-mediated antiviral effect by degradation of FoxJ1. Our findings provide new insights into the antiviral function of FoxJ1, which might help design antiviral drugs or vaccines against ASFV infection.