Development of rapid and simple FCoV RNA detection systems using RT-PCR and RT-RPA combined with STH-PAS to diagnose FIP in cats

Feline infectious peritonitis (FIP) is a fatal disease in cats that is caused by feline coronavirus (FCoV). FCoV RT-qPCR is widely used to diagnose FIP due to its high sensitivity and ability to quantify FCoV RNA. However, its convenience is limited by the need for expensive equipment and/or processing at external laboratories. We herein developed two rapid and simple FCoV RNA detection systems: one combining conventional RT-PCR with the Single Tag Hybridization-Printed Array Strip (STH-PAS) method (the RT-PCR and STH-PAS system) and the other combining RT-RPA, an isothermal nucleic acid amplification method, with STH-PAS (the RT-RPA and STH-PAS system). Evaluations using FCoV RNA standards showed that the limit of detection for the RT-PCR and STH-PAS system was 10^4.2 copies/reaction, while that for the RT-RPA and STH-PAS system was 10⁴ copies/reaction. The clinical performance of these systems was also examined using clinical samples from cats suspected of having FIP and compared to the conventional FCoV RT-qPCR genetic test. The results obtained showed a sensitivity of 66.7 % (95 % CI: 41.0–86.7) and specificity of 100 % (95 %CI: 9.4–100). These systems are a faster and simpler alternative to conventional methods, suggesting their potential in point-of-care testing in veterinary clinics.