Porcine epidemic diarrhea virus does not replicate in porcine monocyte-derived dendritic cells, but activates the transcription of type I interferon and chemokine

Porcine epidemic diarrhea virus (PEDV) belongs to the alphacoronavirus of the Coronaviridae. It is the major etiological agent of the recent outbreaks of piglet diarrhea and death in the US. Limited knowledge is currently available regarding the role of dendritic cells in PEDV infection. Here, we observed that PEDV did not replicate in monocyte-derived dendritic cells as evidenced by the decrease of viral gene transcript copies in infected cells by qRT-PCR and the absence of viral proteins by immunofluorescence staining as well as the absence of virus particles in infected cells by transmission electron microscopy. In addition, PEDV did not compromise cell viability at 48, 72, and 96 h after infection at either a MOI of 2.5 or 5. Interestingly, an increased transcription of type I interferon including interferon-α and β was observed in infected cells compared to mock infected cells. Surprisingly, we did not detect any interferon-β in the supernatants of infected cells. A slight increase in interferon-α protein production in the supernatants of PEDV-infected cells was observed compared to mock infected cells. We also observed a markedly increased transcription of interferon inducible protein −10 (IP-10). Overall, PEDV does not replicate in porcine Mo-DC, but activates the transcription of type I interferon and chemokine IP-10.