Coinfection of porcine deltacoronavirus and porcine epidemic diarrhea virus altered viral tropism in gastrointestinal tract in a piglet model.

Coinfection of porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV) is one of common findings in diarrheal piglets that cause massive economic losses to the pig industry globally. However, the mechanism of the co-infection is unclear. In this study, neonatal non-colostrum-fed piglets were exposed orally with a single infection of PDCoV or PEDV, or coinfection of PDCoV and PEDV. Clinically all viral infected piglets developed watery diarrhea and dehydration in 24 h post-exposure (hpe) and were succumbed to viral diarrhea disease and euthanized at 72 hpe. Histopathologically, acute gastroenteritis is evident in all viral infected piglet. Immunohistochemistry, RNAscope and RT-qPCR demonstrated that PEDV tropism changes from epithelial cells of small intestine to gastric epithelial cells and macrophages in Peyer's patches in the ileum. These findings suggest that coinfection of PDCoV and PEDV can alter PEDV tropism that may affect the outcome of viral disease in piglets. This animal model can be used for the pathogenesis and vaccination of viral coinfection in piglet in the future.