Gold(III) enhanced chemiluminescence immunoassay for detection of antibody against ApxIV of Actinobacillus pleuropneumoniae

We report, for the first time, a chemiluminescence immunoassay (CLIA) method based on AuCl4- -enhanced luminol chemiluminescence (CL) reaction for the highly sensitive detection of ApxIV antibody of Actinobacillus pleuropneumoniae (APP). The AuCl4-, which was the dissolution product of the gold nanoparticle-rabbit anti-pig IgG conjugate, served as an analyte in the CL reaction for the indirect measurement of antibody against ApxIV. The optimal condition of gold dissolution was composed of a 5.0 x 10(-2) M HCl, 1.5 x 10(-2) M NaCl, and 2.5 x 10(-4) M Br-2 solution. Under the optimal conditions, a good correlation between the relative CL photon counting and the dilution coefficient of serum was obtained in the dilution range of 1:160-1:40 000. Based on the analysis of clinical samples, the results indicated that CLIA had remarkable advantages in terms of reliability and practical use compared with indirect hemagglutination (IHA) and enzyme-linked immunosorbent assays (ELISA). The proposed method provided a new tool for the indirect determination of antibody against ApxIV in pig serum samples and showed great potential for numerous applications in immunoassays.