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

Viral RNA burdens and distribution in gnotobiotic piglets infected with the PdCV CVM1 or MI strain. PdCV viral RNAs were detected in all samples in Ohio CVM1-infected piglets (Fig. 6) . At 24 h p.i., 9 to 11 log 10 PdCV RNA copies/g or ml was detected in all samples of the small and large intestines. Viral RNA concentrations reached the highest levels at 48 h p.i. and decreased by 72 h p.i. In the duodenal tissues, viral RNAs declined from 24 to 72 h; only 4.7 log 10 PdCV RNA copies/g was detected in the 72-h duodenal sample, correlating to histological evidence for mucosal epithelial cell regeneration. High levels (roughly 10 log 10 viral RNA/g or ml) of viral RNAs were shed in fecal samples 24 to 72 h p.i. PdCV RNA levels in extraintestinal tissues (lung, liver, kidney, spleen, and blood) were relatively low, ranging from 3.1 to 6.27 log 10 PdCV RNA copies/g of sample. Peripheral blood contained 3.4 to 4.1 log 10 copies of PdCV RNA/ml, indicating viremia. These data demonstrated that viral RNA shedding in intestine and feces significantly exceeded that of the input virus (6 log 10 RNA copies/ piglet) and support the conclusion that PdCV caused enteric infection and replicated rapidly in the gastrointestinal tract.