Development and Application of Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) for Feline Coronavirus Detection

Abstract

Mutated feline coronavirus (FCoV) causes a highly fatal disease in cats, named feline infectious peritonitis (FIP). Common FIP clinical signs represent an accumulation of fluid in the thorax and/or abdomen. Screening tests currently rely on fluid analysis with cytologic examination to differentiate cellular components. Accordingly, accurate ante-mortem diagnosis is prerequisite for effective treatment strategies. This study focused on developing a rapid diagnostic tool for FCoV by using reverse transcription loop-mediated isothermal amplification (RT-LAMP). Clinical
samples composed of bodily fluids, plasma and feces were obtained from FIP-suspected cats (n = 63), apparent healthy cats living with (n = 12) and without (n = 10) clinically ill cats. Following RNA extraction and quantification, the modified RT-LAMP targeting the highly conserved 3’-untranslated region (3’UTR) was thoroughly performed and results were compared to reverse transcription polymerase chain reaction (RT-PCR). The analysis focused on sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The results showed that
all submitted feline fluid samples were 38% (24/63) positive by RT-PCR and 44% (28/63) positive by RT-LAMP. Cats living in the same household with FIP-suspected cats strikingly displayed 98% (11/12) positivity when detected from plasma and/or feces. For cats with no history of previous FIP exposure, the results demonstrated that 30% (3/10) tested positive by RT-PCR compared to 50% (5/10) by RT-LAMP. Additionally, RT-LAMP represented a diagnostic sensitivity and NPV at 100%, while specificity and PPV were over 80%. In conclusion, RT-LAMP assay is applicable to confirm FIP infection in clinical case and to monitor FCoV carrier in healthy cats.