Nicotinamide Efficiently Suppresses Porcine Epidemic Diarrhea Virus and Porcine Deltacoronavirus Replication

Porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV), members of the coronavirus family, mainly cause acute diarrhea, vomiting and dehydration in piglets, and lead to serious economic losses. In this study, we investigated the effects of nicotinamide (NAM) on PEDV and PDCoV replication. NAM treatment significantly inhibited PEDV and PDCoV reproduction. Moreover, the results showed that NAM plays an important role in viral RNA and protein synthesis to inhibit the optimal replication of PEDV and PDCoV rather than viral other replication processes. Furthermore, we demonstrated that NAM treatment inhibits the replication of PEDV and PDCoV, likely by downregulating the expression level of transcription factors through activation of the ERK1/2/MAPK pathway. Overall, this study is the first to suggest that NAM might not only be an important antiviral factor for swine intestinal coronavirus but also a potential candidate to be evaluated against other human and animal coronaviruses.