A QUARTZ-CRYSTAL MICROBALANCE ASSAY FOR DETECTION OF ANTIBODIES AGAINST THE RECOMBINANT AFRICAN SWINE FEVER VIRUS ATTACHMENT PROTEIN P12 INSWINE SERUM

A novel, piezoelectric, quartz crystal microbalance (QCM) biosensor ha s been developed for the detection of antibodies against the recombina nt African swine fever virus attachment protein p12. The protein p12 w as immobilized on the gold surface of the crystal by adsorption. The r esonance frequency of the piezoelectric crystal is associated with a m ass change at the surface. The measurement of the frequency shift due to the reaction between the antigen immobilized on the piezoelectric c rystal and the antibody enables the detection of the antibody. It was possible to monitor the antigen-antibody binding without the use of a label. The use of an amplified mass immunosorbent assay leads to signi ficant enhancement of the signal. In this case, the anti-p12 antibody detection is accomplished by binding the anti-p12 antibody to the p12 protein immobilized on the QCM, followed by addition of an anti-porcin e antibody conjugated to horseradish peroxidase. Subsequent exposure o f 4-chloro-1-naphtol and H2O2 to the bound sandwich complex results in enzymatically amplified deposition of the oxidized 4-chloro-1-naphtho l on the QCM surface, resulting in a frequency change that corresponds to the level of anti-p12 analyte. The method has a low detection limi t (serum samples could be detected as positive in a dilution of 1/1500 ) and results can be obtained in less than 30 min. Since the immobiliz ation of protein is simple it is possible to prepare several crystals and use this method as a screening method. (C) 1998 Elsevier Science B .V. AU rights reserved.