Development of a monoclonal antibody-based colloidal gold immunochromatographic strip for rapid detection of feline coronavirus

Feline infectious peritonitis (FIP), caused by feline coronavirus (FCoV), is a fatal disease with no effective vaccine. Early detection is crucial for FIP management, and a rapid, accurate diagnostic method is urgently needed. Hence, the purpose of this study was to establish a rapid, sensitive, specific immunochromatographic strip (ICS) for clinical detection of FIP. We selected the highly conserved N protein of FIPV and expressed recombinant N protein as an immunogen to prepare monoclonal antibodies (mAbs). Five mAbs specific to FIPV were produced. The antigenic epitopes recognized by the 2B10 and 10E7 mAbs used for ICS preparation were identified, and the structure and conservation of the epitopes were analyzed. Subsequently, we paired the 2B10 and 10E7 mAbs, assembled the ICS, and implemented several optimization measures. The specificity of the ICS was confirmed by positive reactions with FIPV-positive samples and negative reactions with FHV, FPV, and FCV. Sensitivity testing detected FIPV suspensions (TCID₅₀ = 10^6.5/mL) diluted to 1: 512. The ICS showed 98.3 % agreement with RT-PCR results in detecting 60 suspected samples and remained stable for 6 months at room temperature. In conclusion, this study developed a simple, sensitive, and specific ICS for the detection of FIPV.