A Dual-Label Time-Resolved Fluorescence Immunoassay for the Simultaneous Qualitative/Quantitative Detection of Hepatitis A and Hepatitis E Virus IgM Antibodies

Abstract

Background: Clinically, the symptoms of hepatitis A virus (HAV) and hepatitis E virus (HEV) infection are similar, which can easily lead to misdiagnosis. This study was performed to establish a new detection assay to distinguish HAV and HEV infections using a time-resolved fluorescence immunoassay (TRFIA) via the detection of HAV-IgM and HEV-IgM antibodies in serum. Method: A capture TRFIA was established after optimization. Anti-IgM antibodies were immobilized on 96-well plates and used to capture all IgM (including HAV-IgM and HEV-IgM) antibodies, then they were banded together with HAV-specific antigen (HAVAg) and HEV-specific antigen (HEVAg) that labeled with europium (III) (Eu³⁺) and samarium (III) (Sm³⁺) respectively. Lastly, the fluorescence intensity was measured with time-resolved fluorometry. Results: For HAV-IgM, the sensitivity was 0.25 mIU/mL, while for HEV-IgM was 0.32 mIU/mL. In serum samples, the inter-assay and intra-assay CVs (Coefficient of Variations) were under 10% and had high specificity. HAV-IgM and HEV-IgM cut-off values were 0.36 mIU/mL and 0.57 mIU/mL, respectively. Conclusions: Both tests demonstrated detection effect of the TRFIA method we developed is on par with that of clinical ELISA (enzyme-linked immunosorbent assay) methods. TRFIA method is appropriate for qualitatively and quantitatively detecting HAV-IgM and HEV-IgM antibodies to discriminate between HAV and HEV infections.