Comparative analysis of feline coronavirus (FCoV) by molecular techniques

Feline coronavirus (FCoV) infection is an important viral problem threatening feline health as it can lead to the fatal disease Feline Infectious Peritonitis (FIP). In this study, we aimed to evaluate the diagnostic performance of a uniquely designed Reverse Transcriptase Loop-mediated Isothermal Amplification (RT-LAMP) method for the detection of FCoV in cats with suspected FIP in comparison with a standard nested PCR (nPCR) method. For this purpose, ascites fluid (n=25), blood (n=17) and rectal swab (n=8) samples from 50 cats with suspected FIP were used. All samples were analyzed for the presence of FCoV RNA by nested PCR (nPCR), which is accepted as the reference method, and fluorimetric and colorimetric RT-LAMP methods developed to target the FCoV S2 gene region in our study. Of the 50 samples analyzed, 15 (30%) were positive by nPCR, while 23 (46%) were positive by the RT-LAMP method. In addition to detecting all samples found positive by nPCR, the RT-LAMP test gave positive results in 8 more samples found negative by nPCR. The highest positivity rate in both tests was found in ascites fluid samples. Furthermore, there was complete agreement (100%) between colorimetric and fluorimetric RT-LAMP results. As a result of this study, it was demonstrated that the developed RT-LAMP method has a higher detection rate than the standard nPCR method in detecting FCoV RNA in FIP suspected samples. Furthermore, the practicality and reliability of colorimetric LAMP demonstrated that this assay has significant potential for rapid diagnosis, especially in clinical settings.