Ducklings Were Susceptible to Swine Acute Diarrhea Syndrome Coronavirus Under Experimental Conditions

Swine acute diarrhea syndrome coronavirus (SADS-CoV), similar to other coronaviruses, exhibits extensive host tropism and has caused huge losses to the pig industry since its first outbreak in 2017. However, the susceptibility of SADS-CoV in waterfowl remains unclear. In the present study, 10-day-old ducklings were orally administered 5.95 log₁₀ TCID₅₀ (the tissue culture infective dose 50%) of SADS-CoV, with a medium serving as a control treatment, to assess ducklings' susceptibility. Results indicated that the ducklings exhibited mild diarrhea symptoms, experienced slow weight gain, and one duckling died seven days after inoculation. Histopathological examination revealed that the viral infection caused pathological damage to the spleen, intestine, and lungs. Tissue immunofluorescence demonstrated viral replication in the spleen, lungs, and intestine. This study provides the first evidence that SADS-CoV can infect ducklings under laboratory conditions. Given that waterfowl may serve as significant reservoirs for various viruses, this finding raises considerable concerns.