Abstract: Porcine deltacoronavirus (PDCoV) is a highly pathogenic virus that causes acute watery diarrhea, vomiting and high mortality (30%～50%) in suckling piglets, posing a significant threat to the global swine industry. To develop a sensitive and accurate detection method for PDCoV, this study designed specific primers and probes targeting the conserved region of the PDCoV nucleocapsid (N) gene, optimized the reaction system, and successfully established a TaqMan-based fluorescence quantitative PCR (qPCR) assay. Using a recombinant plasmid containing the PDCoV N gene as a standard, the method exhibited a strong linear correlation within the range of 8.79×101 to 8.79×108 copies/μL (R2=0.997, slope=-3.236), with optimal primer and probe concentrations of 0.4 μmol/L and 0.2 μmol/L, respectively. The assay demonstrated high sensitivity, with a detection limit of 8.79 copies/μL; excellent specificity, with no cross-reactivity observed with Porcine Epidemic Diarrhea Virus (PEDV), Pseudorabies Virus (PRV), or Porcine Reproductive and Respiratory Syndrome Virus (PRRSV); and good reproducibility, with inter- and intra-assay coefficients of variation below 1.5%. The qPCR method developed in this study provides a reliable technical platform for the clinical diagnosis and epidemiological surveillance of PDCoV.

Key words: pig, PDCoV, N gene, TaqMan qPCR, piglet diarrhea