Origin, Evolution, and Virulence of Porcine Deltacoronaviruses in the United States

Ma, Yuanmei; Zhang, Yu; Liang, Xueya; Lou, Fangfei; Oglesbee, Michael; Krakowka, Steven; Li, Jianrong

PdCV in Gn piglets: similarities with PEDV and TGEV. We have shown that both the PdCV Ohio CVM1 and MI strains induce significant disease in Gn pigs. The pathogenesis of TGEV and PEDV is well studied. Both TGEV and PEDV are members of the Alphacoronavirus genus and cause almost identical clinical signs and gross and histological lesions in young, susceptible pigs (6, 12, 24, 26) , even though there is no serological cross-reactivity between TGEV and PEDV. In contrast, PdCV is a member of the genus Deltacoronavirus most closely related to avian CoVs (15) . The overall clinical disease associated with PdCV infection is very similar to that induced by TGEV and PEDV, except that vomiting is more commonly seen in PdCV-infected piglets and the mortality rates are reported to be lower (on the order of 40 to 50%) than those for PEDV and TGEV (90 to 100%). Similar to TGEV and PEDV, PdCV replicates extensively in the small intestine. High levels of genomic RNA were detected in feces, intestinal contents, and tissues. A large number of antigen-positive cells were detected in all sections of the small intestine. Intestinal gross and histologic findings in PdCV-infected piglets are similar to those described for PEDV and TGEV. Finally, moderate levels of PdCV RNA were detected in blood and extraintestinal tissues, consistent with viremic dissemination similar to what has been observed in TGEVand PEDV-infected piglets.