title: Comparison of real-time reverse transcriptase polymerase chain reaction of peripheral blood mononuclear cells, serum and cell-free body cavity effusion for the diagnosis of feline infectious peritonitis.
abstract: Objectives Diagnosis of feline infectious peritonitis (FIP) remains challenging, especially in cats without effusions. The objective of this study was to evaluate the sensitivity and specificity of a real-time reverse transcriptase polymerase chain reaction (RT-PCR) detecting feline coronavirus (FCoV) RNA in peripheral blood mononuclear cells (PBMCs) and serum in comparison with the same real-time RT-PCR in cell-free body cavity effusion. Methods This prospective case-control study included 92 cats. Forty-three cats had a definitive diagnosis of FIP, established either by histopathological examination (n = 28) or by positive immunofluorescence staining of FCoV antigen in macrophages of effusions (n = 11), or by both methods (n = 4). Forty-nine control cats had other diseases but similar clinical signs. Real-time RT-PCR was performed on PBMCs of 37 cats (21 cats with FIP, 16 controls), on serum of 51 cats (26 cats with FIP, 25 controls) and on cell-free body cavity effusion of 69 cats (36 cats with FIP, 33 controls). Sensitivity, specificity, positive and negative predictive value, including 95% confidence intervals (CI), were calculated. Results Real-time RT-PCR of PBMCs, serum and cell-free body cavity effusion showed a specificity of 100% (95% CI 79.4-100% in PBMCs, 86.3-100% in serum, 89.4-100% in cell-free body cavity effusion) and a sensitivity of 28.6% (95% CI 11.3-52.2%) in PBMCs, 15.4% (95% CI 4.4-34.9%) in serum and 88.9% (95% CI 73.9-96.9%) in cell-free body cavity effusion to diagnose FIP. Conclusions and relevance Although it is known that RT-PCR can often provide false-positive results in healthy cats, this real-time RT-PCR was shown to be a specific tool for the diagnosis of FIP when applied in a clinical setting. Sensitivity in cell-free body cavity effusion was high but low in PBMCs and serum. PBMC samples showed a higher sensitivity than serum samples, and are therefore a better choice if no effusion is present.
authors.affiliation: 1 Clinic of Small Animal Medicine, LMU University of Munich, Germany.
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Doenges
authors.affiliation: 1 Clinic of Small Animal Medicine, LMU University of Munich, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Weber
authors.affiliation: 1 Clinic of Small Animal Medicine, LMU University of Munich, Germany.
authors.forename: Roswitha
authors.initials: R
authors.lastname: Dorsch
authors.affiliation: 2 Institute for Infectious Diseases and Zoonoses, LMU University of Munich, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Fux
authors.affiliation: 1 Clinic of Small Animal Medicine, LMU University of Munich, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Hartmann
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology; D016022:Case-Control Studies; D002415:Cats; D016765:Coronavirus, Feline / Q000276:immunology / Q000302:isolation & purification; D016766:Feline Infectious Peritonitis / Q000097:blood / Q000175:diagnosis*; D005260:Female; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008297:Male; D011446:Prospective Studies; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D012680:Sensitivity and Specificity
chemical_list: D012367:RNA, Viral