Measurement of Feline Alpha-1 Acid Glycoprotein in Serum and Effusion Using an ELISA Method: Analytical Validation and Diagnostic Role for Feline Infectious Peritonitis.

Abstract

BACKGROUND: Alpha-1 acid glycoprotein (AGP) may support a clinical diagnosis of feline infectious peritonitis (FIP). In this study, we assessed the analytical and diagnostic performances of a novel ELISA method to measure feline AGP. METHODS: AGP was measured in sera and effusions from cats with FIP (n = 20) or with other diseases (n = 15). Precision was calculated based on the coefficient of variation (CV) of repeated testing, and accuracy was calculated by linearity under dilution (LUD). RESULTS: The test is precise (intra-assay CVs: <6.0% in individual samples, <15.0% in pooled samples; inter-assay CVs <11.0% and <15.0%) and accurate (serum LUD r: 0.995; effusion LUD r: 0.950) in serum and in effusions. AGP is higher in cats with FIP than in other cats in both serum (median: 1968, I-III interquartile range: 1216-3371 &#x3bc;g/mL and 296, 246-1963 &#x3bc;g/mL;= 0.009) and effusion (1717, 1011-2379 &#x3bc;g/mL and 233, 165-566 &#x3bc;g/mL;< 0.001). AGP discriminates FIP from other diseases (area under the receiver operating characteristic curve: serum, 0.760; effusion, 0.877), and its likelihood ratio is high (serum: 8.50 if AGP > 1590 &#x3bc;g/mL; effusion: 3.75 if AGP > 3780 &#x3bc;g/mL). CONCLUSION: This ELISA method is precise and accurate. AGP in serum and in effusions is a useful diagnostic marker for FIP.