In Vivo Diagnosis of Feline Infectious Peritonitis by Comparison of Protein Content, Cytology, and Direct Immunofluorescence Test on Peritoneal and Pleural Effusions

Abstract

The diagnosis of feline infectious peritonitis (FIP) is hampered by the characteristic etiopathogenesis of the disease. 9 The coronavirus responsible for the disease (FIPV) originated by a mutation in the widespread feline enteric coronavirus (FECV). 9,14 These coronaviruses are both phenotypically and genotypically identical, as demonstrated by polymerase chain reaction (PCR). 14 Both feline coronaviruses (FCoVs) are able to trigger the production of antibodies. High antiFCoV titers are also detectable in healthy cats in FECVendemic catteries, 9,10 and the formation of immune complexes could results in negative serology in symptomatic cats. 8 Furthermore, false-positive results occur from cross-reactivity with coronaviruses of other species, such as canine coronavirus (CCV) or transimissible gastroenteritis virus (TGEV), or with extraneous noncoronavirus proteins that are copurified with the FCoV and included in commercially available diagnostic enzyme-linked immunosorbent assay kits. 1 Hematology, serum chemistry, and serum protein electrophoresis give only a strongly suggestive but nonpathognomonic pattern of FIP. 9,12,13 In the effusive forms, diagnosis could be improved by cytology 3 and protein analysis of the fluid. 9,11-13 Although FCoV RNA has been demonstrated in the plasma of healthy cats in FECV-endemic catteries, 6 FCoVs detected from areas other than the intestinal lumen should be interpreted as FIPV, particularly if the viruses are detected in lesions 15 or effusions. 2 In this study, the results obtained using 3 different diagnostic methods (anti-FCoV direct immunofluorescence test, cytology, and protein analysis) for 110 cats with effusions over a 5-year period were compared to determine the utility of these methods for diagnosing FIP from analysis of the effusion alone. Cats with clinically detectable effusion were examined (Table 1), although in some cases clinical and laboratory data (serum chemistry, ultrasonography, macroscopic appearance of the effusion) suggested diseases other than FIP.Approximately 2 ml of effusion was withdrawn from each cat before death (72 cats) or within 2 hours after death (38 cats). The sampled fluid was put in a tube containing ethylenediamine tetraacetic acid. The protein content of the effusions of 51 cats was evaluated in a discrete autoanalyzer a by the biuret method. b Fifty to 100 l of fluid was cytocentrifuged c within 15 hours at 130 ϫ g for 10 minutes. Two Received for publication August 25, 1997.slides were obtained from each fluid sample; 1 slide was routinely stained with May Grünwald-Giemsa and the other was used immediately or after storage at Ϫ20 C for no more than 1 week for direct immunofluorescence (DIF) tests as previously described. 2 The slides were fixed and dehydrated in acetone : methanol (3:1) for 20 minutes and incubated for 30 minutes at 37 C in a moist chamber with 100 l of a feline polyclonal fluorescein-conjugated antiserum d detecting FCoV biotypes I and II and cross-reacting with TGEV and CCV. After washing 4 times for 10 minutes e...

Body Cavity Fluids

“…A positive result ( Fig. Using direct immunofluorescence to detect FCoV antigens within effusion macrophages, there was a sensitivity of 100% and a specificity of 71.4% (Litster et al, 2013)-results similar to those previously reported (Paltrinieri et al, 1999). Unfortunately, a negative result does eliminate FIP diagnostically because the NPV of 57% is poor (Hartmann et al, 2003;Parodi et al, 1993).…”

“…Classification as an inflammatory effusion is based primarily on the presence of high total protein (often greater than 4.5 g/dL), which is a reflection of a similar elevation in serum protein, as well as the product of vasculitis and increased vascular permeability. 6-14B) (Norris et al, 2005;Paltrinieri et al, 1999). In a majority of cases the predominant cell is the nondegenerate neutrophil (Fig.…”

“…Paltrinieri et al (1999) found that a total protein greater than 3.5 alone had a sensitivity of 87.1% and a specificity of 60%. The total protein, A:G ratio, and percent globulin in effusions have all been evaluated as a tool for diagnosing FIP from effusions.…”

Performances of different diagnostic tests for feline infectious peritonitis in challenging clinical cases

“…This electrophoretic pattern is also evident in effusions when present (Shelly and others 1988, Paltrinieri and others 1998). The macroscopic, physico‐chemical and cytological pattern of the effusion is also typical and has a high positive predictive value for FIP (Paltrinieri and others 1999). It is described as a yellowish, transparent to cloudy, sticky fluid, often with fibrin clots and characterised by high protein content, high specific gravity and variable amounts of cells, mostly composed of non‐degenerated neutrophils, macrophages and lymphocytes in a granular proteinaceous eosinophilic background.…”

Absence of surface expression of feline infectious peritonitis virus (FIPV) antigens on infected cells isolated from cats with FIP

“…FIPV-infected cells are detected in the pyogranulomas and, based on morphology and the granulocyte/ monocyte/macrophage marker calprotectin, defined as macrophages (Weiss and Scott, 1981;Kipar et al, 1998). Infected mononuclear cells were also isolated from exudates (Cammarata Parodi et al, 1993;Paltrinieri et al, 1999). In one way or another, these infected cells succeed in staying alive and transmitting www.elsevier.com/locate/vetmic Veterinary Microbiology 121 (2007) [131][132][133][134][135][136][137] virus to new susceptible cells in the presence of a high concentration of antibodies.…”