Evaluation of a Novel CLIA Monotest Assay for the Detection of Anti-Hepatitis E Virus-IgG and IgM: A Retrospective Comparison with a Line Blot and an ELISA

Abstract

Despite the increasing relevance of Hepatitis E, an emerging disease endemic in developing and with increasing numbers of sporadic cases in industrialized countries, commercial tests are mainly based on batch oriented serological assays. In this retrospective study, we compared a line immunoassay (LIA; recomLine HEV, Mikrogen) and an ELISA (EIA; Anti-Hepatitis E Virus ELISA, Euroimmun) with a novel chemoluminescence immunoassay in a monotest format (CLIA; Hepatitis E VirClia, Vircell). Twenty sera of PCR proven cases of hepatitis E and 68 blood samples serologically pre-characterized were included. Applying the WHO reference standard, the CLIA demonstrated the highest analytical sensitivity for IgG and IgM. The combinations of CLIA/EIA (IgG and IgM) and CLIA/LIA (IgG) measurements showed substantial correlation. Compared to overall antibody detection (seropositivity in ≥2 assays), CLIA correlation was excellent, outperforming LIA (IgM) and EIA (IgG and IgM). Minor IgM cross reactivity in samples of patients with acute EBV infection was observed in all three assays. The CLIA showed good performance in diagnostic samples compared to established LIA and EIA assays. Due to its ready-to-use monotest format, the CLIA allows simple, time- and cost-effective handling of single samples. These qualities make the assay suitable for diagnostics, especially in the emergency setting and for low-throughput laboratories.

Keywords: CLIA; ELISA; HEV; LIA; antibody; hepatitis E virus; monotest; serology.

Figure 1

Linearities and detection limits of anti-HEV-antibody assays applied to serial dilutions of the WHO standard. Values indicate the arithmetic mean of two independent runs. The horizontal bars in (A,C) represent areas with borderline results. (A) IU/mL (IgG) and ratio (IgM) cut-off: ≥1.1 = positive; <0.8 = negative (B) S/CO band intensity of O2CGt3 cut-off: ≥1.0 = positive; <1.0 = negative (C) RLU index IgG cut-off: ≥1.1 = positive; 0.9–1.1 = equivocal; <0.9 = negative; RLU Index IgM cut-off: ≥0.5 positive; 0.4–0.5 = equivocal; <0.4 = negative.

Figure 2

Comparison of measurement results for clinical samples. Fifty-four sera were analyzed applying the three assays. (A–C) represent IgG measurements, (D,E) IgM measurements. (A,D}) compare results from EIA and CLIA, (B,E) from LIA and CLIA, (C,F) from LIA and EIA, respectively. Gray bars mark areas with borderline in-terpretation.

Figure 3

Concordance of positive results. Overlapping areas demonstrate concordance between the different anti-HEV-antibody assays for IgM (A) and IgG detection (B).