Fast measurement of serum amyloid A in different specimens from swine by using a new one-step time-resolved fluorescent immunoassay

Abstract

The objective of the present study was to develop a one-step, fast, competitive time-resolved fluorescent immunoassay to determine porcine serum amyloid A (SAA) by using species-specific reagents. The assay consisted of an all-in-one format involving only 55 min of incubation that was adapted and validated for use in 3 different specimens: serum, saliva, and meat juice. The method had overall within- and between-run coefficients of variation under 8% and 12%, respectively, and coefficients of determination higher than 0.93 for linearity under dilution analysis for all specimens. The limits of detection were 0.32 mg/l, 0.28 mg/l, and 1.74 mg/l for serum, saliva, and meat juice measurements, respectively. Upper and lower limits of quantification were determined for each sample type and resulted in wide assay ranges that allowed a precise SAA measurement in all the fluids investigated. Statistically significant differences (P = 0.0004 for serum and P < 0.0001 for the saliva and meat juice samples) in SAA levels were found when healthy (n = 20) and diseased (n = 20) pigs were compared. The obtained results indicate that this fast, sensitive, and robust assay for SAA measurement could be of use to determine health and welfare status in swine by employing alternative samples to serum.