A direct and rapid RT-LAMP method for Point-of-Care test of porcine deltacoronavirus.

Porcine deltacoronavirus (PDCoV) is a significant enteric pathogen in swine, necessitating rapid and accessible diagnostic tools for effective control. In this study, we developed a streamlined, extraction-free Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) assay integrated with a TaqMan probe for on-site PDCoV detection. By targeting the conserved N gene and modifying the loop primer (LB) as a fluorescence probe, a highly specific reaction system was established. The assay demonstrated high sensitivity, with a limit of detection (LOD) of 9.3 copies/μL for cDNA and 5.9 copies/μL for RNA within 40 min, while showing no cross-reactivity with common swine viruses. Reproducibility assays yielded a coefficient of variation (CV) of < 2.5%, indicating excellent stability. Furthermore, the method was successfully integrated with nucleic acid extraction-free technology for fecal sample analysis. In clinical validation using 75 samples, the assay showed 100% concordance with column-based RT-LAMP and standard RT-qPCR methods. This extraction-free RT-LAMP-TaqMan assay offers a rapid, reliable, and cost-effective Point-of-Care Testing (POCT) solution for PDCoV surveillance in swine herds.