A colloidal gold immunochromatographic test strip based on mAbs anti-S protein to detect porcine deltacoronavirus

Porcine deltacoronavirus (PDCoV), an important porcine enteric coronavirus, poses a serious threat to the swine industry. Effective prevention and control require early diagnosis and detection. Previously developed colloidal gold immunochromatographic test strips targeted nucleocapsid protein. However, several studies have reported cross-reactivity between PDCoV and porcine epidemic diarrhea virus, mainly due to similarities in the nucleocapsid protein. To achieve rapid and specific detection, we developed a double-antibody sandwich colloidal gold immunochromatographic test strip using monoclonal antibodies against the PDCoV spike protein. The assay detected PDCoV within 15 min, with a detection limit of 10⁵ TCID₅₀/mL. No cross-reactivity was observed with Porcine epidemic diarrhea virus (PEDV), Transmissible Gastroenteritis virus (TGEV), or Porcine rotavirus (PoRV), confirming strong specificity. Intra- and inter-batch analyses showed no significant differences, indicating good reproducibility. Variation with 77 clinical samples (fecal samples, fecal swabs, and intestinal tissues) demonstrated 92.2 % coincidence rate with RT-qPCR. PDCoV was detected in 67.53 % of samples using the test strip and in 72.72 % of samples using RT-qPCR. These results indicate that the test strip provides rapid, convenient, and reliable detection of PDCoV, with high specificity, sensitivity, and stability. It represents a valuable tool for the clinical diagnosis of PDCoV.