Figure 1 - Linearity of HEV IgG determination over multiple dilution levels. Three samples in which HEV IgG was detectable at high levels were serially diluted in HEV IgG negative serum and measured in duplicate. The 1:64 dilution proved negative in both the recomWell HEV IgG assay (cut-off 20 U/ml) (a) and the LIAISON® Murex anti-HEV IgG assay (cut-off 0.3 IU/ml) (b). The 1:16 dilution level was consistently found to be positive in the recomLine HEV IgG assay, while at the 1:32 dilution level only one of the three sera was positive in the immunoblot. The raw data can be found in the supplement.

HEV-IgM

The recom Well HEV IgM and the LIAISON® Murex anti-HEV IgM immunoassays were compared by analyzing 102 serum samples. A sensitivity of 67.9 % [95% CI, 0.54 to 0.79] and a specificity of 100% [95% CI, 0.91 to 1.00] was calculated (Table 2). An aberrant result was demonstrated in 17 samples, so the WANTAI HEV IgM immunoassay was used to decide how to score these sera. Nine out of 17 samples were quoted HEV IgM negative by the WANTAI assay and confirmed the result of the LIAISON® Murex IgM CLIA (Supplementary data). Thus, a sensitivity of 81.8% [95%CI, 0.68 to 0.91] and a specificity of 100% [95% CI, 0.91 to 1.00] was calculated for the LIAISON test. When immunoblot results were considered, the sensitivity and specificity of the latter was 88.9 % [95% CI, 0.71 to 0.97] and 53.9 % [95% CI, 0.35 to 0.71], respectively (Table 2). HEV RNA was not detected in any of the 17 discrepant sera by RT-PCR.
Table 2 – Agreement of the recomWell/recomLine HEV IgM and DiaSorin LIAISON® Murex anti-HEV IgM immunoassays. The raw data can be found in the supplement.* HEV RNA was not detected in these 17 samples by RT-PCR. In the recomWell HEV IgM test, a borderline result means that the antibody concentration is in the range of 20 to 24 IU/ml.