title: Detection of feline coronavirus spike gene mutations as a tool to diagnose feline infectious peritonitis.
abstract: Objectives Feline infectious peritonitis (FIP) is an important cause of death in the cat population worldwide. The ante-mortem diagnosis of FIP in clinical cases is still challenging. In cats without effusion, a definitive diagnosis can only be achieved post mortem or with invasive methods. The aim of this study was to evaluate the use of a combined reverse transcriptase nested polymerase chain reaction (RT-nPCR) and sequencing approach in the diagnosis of FIP, detecting mutations at two different nucleotide positions within the spike (S) gene. Methods The study population consisted of 64 cats with confirmed FIP and 63 cats in which FIP was initially suspected due to similar clinical or laboratory signs, but that were definitively diagnosed with another disease. Serum/plasma and/or effusion samples of these cats were examined for feline coronavirus (FCoV) RNA by RT-nPCR and, if positive, PCR products were sequenced for nucleotide transitions within the S gene. Results Specificity of RT-nPCR was 100% in all materials (95% confidence interval [CI] in serum/plasma 83.9-100.0; 95% CI in effusion 93.0-100.0). The specificity of the sequencing step could not be determined as none of the cats of the control group tested positive for FCoV RNA. Sensitivity of the 'combined RT-nPCR and sequencing approach' was 6.5% (95% CI 0.8-21.4) in serum/plasma and 65.3% (95% CI 50.4-78.3) in effusion. Conclusions and relevance A positive result is highly indicative of the presence of FIP, but as none of the control cats tested positive by RT-nPCR, it was not possible to confirm that the FCoV mutant described can only be found in cats with FIP. Further studies are necessary to evaluate the usefulness of the sequencing step including FCoV-RNA-positive cats with and without FIP. A negative result cannot be used to exclude the disease, especially when only serum/plasma samples are available.
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Felten
authors.affiliation: 2 LABOKLIN GmbH & Co KG, Bad Kissingen, Germany.
authors.forename: Karola
authors.initials: K
authors.lastname: Weider
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Doenges
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Gruendl
authors.affiliation: 3 Institute of Veterinary Pathology, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Kaspar
authors.initials: K
authors.lastname: Matiasek
authors.affiliation: 3 Institute of Veterinary Pathology, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Hermanns
authors.affiliation: 2 LABOKLIN GmbH & Co KG, Bad Kissingen, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Mueller
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Lara
authors.initials: L
authors.lastname: Matiasek
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Fischer
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Weber
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Hirschberger
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wess
authors.affiliation: 1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Hartmann
mesh_terms: D000818:Animals; D001483:Base Sequence; D016022:Case-Control Studies; D002415:Cats; D016765:Coronavirus, Feline / Q000235:genetics / Q000302:isolation & purification*; D016766:Feline Infectious Peritonitis / Q000175:diagnosis* / Q000821:virology; D005260:Female; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary; D012367:RNA, Viral / Q000032:analysis; D012680:Sensitivity and Specificity
chemical_list: D012367:RNA, Viral