Development of a time-resolved fluoroimmunoassay for Epstein–Barr virus viral capsid antigen IgA antibody in human serum

Abstract

Viral capsid antigen (VCA) IgA is one of the most commonly tested antibodies for Epstein–Barr virus (EBV) in the clinic and is a proven biomarker to predict the risk of nasopharyngeal carcinoma (NPC) and other diseases. At present, a VCA-IgA antibody is used for clinical diagnosis by enzyme-linked immunosorbent assay (ELISA), which can detect samples only qualitatively or semi-quantitatively, with unsatisfactory sensitivity and specificity. In this study, an indirect time-resolved fluoroimmunoassay (TRFIA) using Eu3+ labeled mouse anti-human IgA monoclonal antibodies as a tracer was developed. This method produced a linear range of 0–30AU/mL, with a limit of detection of 0.018AU/mL. The intra- and inter-assay precisions were 1.62–4.30% and 3.56–7.57%, respectively. TRFIA showed no cross-reactivity against potentially interfering substances and a better sensitivity and specificity compared with commercial ELISA. This study confirmed that an indirect TRFIA meets the requirement for clinical testing and could be an alternative to detect VCA-IgA levels in human serum in the clinic.