Identification of coronaviral antibodies and coronavirus - specific antibody complexes in ascites fluid of cats diagnosticated with feline infectious peritonitis

Abstract

Feline infectious peritonitis (FIP) is an infectious lethal cat diseases, prodused by a mutant feline coronavirus (feline infectious peritonitis virus), which is manifested in two clinical forms. Dry form may go unnoticed or be confused with other diseases. Wet form, however, evolve with ascites fluid accumulation, its appearance being correlated with end-stage of the disease. Research has pursued the efficiency of direct immunofluorescence test for the identification of coronavirus - anticoronavirus antibody complexes in ascites fluid. Nine ascites fluid samples, obtained from cats aged between 1,7 months and 13 years, diagnosed with feline infectious peritonitis, were analyzed. The antibody titrers were assessed using indirect immunofluorescence on pig kidney (PK) cell cultures infected with TGEV, on three samples, titres ranging from 1/25 and 1/625. All nine ascites fluid samples tested by direct immunofluorescence for detection of coronavirus specific antibodies complexes were positive. In images obtained with UV in microscopy, fluorescence being seen in the macrophages under the form of a ring arranged on the periphery of the cell membrane and fluorescence localized intracellularly, probably internalized immune complexes. The results lead us to recommend the use of this test for FIP rapid diagnostic.