Neutralizing epitope mapping for deltacoronavirus receptor-binding domain and seroepidemiological survey across different animal species

motif was found to be indispensable for the conformational recognition by mAb 3A11. Using these mAbs, we developed two blocking enzyme-linked immunosorbent assay (bELISA) methods (bELISA-1C12 and bELISA-3A11). Evaluation of 150 clinical samples demonstrated that bELISA-1C12 exhibited 93.3% concordance with a virus neutralization test (VNT), indicating higher diagnostic sensitivity than bELISA-3A11 (92.7%). A large-scale serosurvey of pig populations across ten Chinese provinces in 2025, conducted using bELISA-1C12, revealed a PDCoV seropositivity rate of 13.6%. Notably, when extending the serological screening to 21 additional animal species, we detected PDCoV antibodies in peafowl serum for the first time, suggesting possible exposure to the virus. This study identifies key antigenic epitopes on the PDCoV RBD and provides valuable tools for epidemiological surveillance and assessing the transmission risk of PDCoV.