Evaluation and validation of a duck IgY antibody-based immunoassay for high-sensitivity C-reactive protein: avian antibody application in clinical diagnostics.

Abstract

High-sensitivity C-reactive protein (hs-CRP) is considered one of the most promising markers for cardiac risk assessment (1). A highly sensitive and interference-resistant CRP assay plays an important role in accurate CRP measurements (2)(3); therefore, manufacturers of in vitro diagnostics have begun modifying their existing CRP assays to meet the requirements. Mammalian antibodies, e.g., rabbit, mouse, and goat IgGs, are the major ones used in clinical immunoassays, but they have some drawbacks. Within the past 10 years, it has been reported that rheumatoid factor and heterophilic antibodies present in samples have caused false-positive results in CRP measurements (4)(5)(6). In addition, monoclonal antibodies for use as diagnostic and therapeutic reagents can induce human anti-mouse antibodies, which may interfere with mammalian IgGs in immunoassays, especially in the sandwich-type methods (7). To eliminate interference without increasing costs, avian antibodies are now considered potential candidates to improve current immunoassays. One such assay, the CRPex-HS® C-Reactive Protein LIT assay (Good Biotech Corp., Taiwan), based on latex microparticle-enhanced immunoturbidimetry, has been developed and is commercially available. The CRPex-HS CRP LIT assay is intended to measure serum hs-CRP concentrations with use of a duck antibody. The duck anti-CRP IgY (ΔFc) antibody is a good substitute for traditional mammalian antibodies. The antibody, purified from egg yolks of white Pekin ducks (Anas platyrhynchos) , is coupled to polystyrene microparticles. When CRP in the serum sample encounters microparticles containing the duck anti-CRP IgY (ΔFc), it agglutinates and the turbidity is measured at 570 nm. The assay calibration range is 0–20.0 mg/L. Practical CRP measurements by the CRPex-HS CRP LIT assay are conducted on a common automated chemistry analyzer, the Hitachi 717. …