To investigate the effect of capsaicin(CAP)on the replication of bovine viral diarrhea vi-rus(BVDV).Bovine nasal turbinate osteoblasts(BT)infected with BVDV served as the research model,and viral gene and protein levels were evaluated using RT-qPCR and Western blot.Moreo-ver,molecular docking,molecular dynamics simulation,and oil red O staining were applied to ana-lyze the mechanism by which CAP inhibits BVDV replication.The results revealed no significant effect of CAP at 6.25,12.5,25,and 50 mg/L on the viability of BT cells.CAP was found to signifi-cantly inhibit BVDV 5′UTR RNA and E2 protein levels,according to the antiviral effect study.Molecular docking and molecular dynamics simulations indicated that CAP could bind with high affinity to the active site of PI3K.Additional mechanistic studies indicated that CAP significantly reduced the activation of the PI3K/AKT signaling pathway triggered by BVDV.Furthermore,CAP notably decreased the mRNA levels of FASN,SREBP-1,and ACC-1,which are crucial fatty acid synthesis enzymes in the downstream PI3K/AKT signaling pathway,as well as the levels of lipid droplets.Interestingly,the addition of exogenous oleic acid greatly diminished the antiviral effec-tiveness of CAP and significantly lowered the mRNA levels of IFN-α and IFN-β.The results reveal for the first time that CAP can inhibit BVDV replication,establishing a foundation for its preven-tion and the development of feed additives.

To investigate the effect of capsaicin(CAP)on the replication of bovine viral diarrhea vi-rus(BVDV).Bovine nasal turbinate osteoblasts(BT)infected with BVDV served as the research model,and viral gene and protein levels were evaluated using RT-qPCR and Western blot.Moreo-ver,molecular docking,molecular dynamics simulation,and oil red O staining were applied to ana-lyze the mechanism by which CAP inhibits BVDV replication.The results revealed no significant effect of CAP at 6.25,12.5,25,and 50 mg/L on the viability of BT cells.CAP was found to signifi-cantly inhibit BVDV 5′UTR RNA and E2 protein levels,according to the antiviral effect study.Molecular docking and molecular dynamics simulations indicated that CAP could bind with high affinity to the active site of PI3K.Additional mechanistic studies indicated that CAP significantly reduced the activation of the PI3K/AKT signaling pathway triggered by BVDV.Furthermore,CAP notably decreased the mRNA levels of FASN,SREBP-1,and ACC-1,which are crucial fatty acid synthesis enzymes in the downstream PI3K/AKT signaling pathway,as well as the levels of lipid droplets.Interestingly,the addition of exogenous oleic acid greatly diminished the antiviral effec-tiveness of CAP and significantly lowered the mRNA levels of IFN-α and IFN-β.The results reveal for the first time that CAP can inhibit BVDV replication,establishing a foundation for its preven-tion and the development of feed additives.