Table 3.
Performance of EHMIL serum HEV IgM and HEV IgA and saliva HEV IgA assays.
| HEV immunoassay | Samples | Cut-off | Positive | Negative | Sensitivity | Specificity |
|---|---|---|---|---|---|---|
| Wantai HEV IgM | 136a | 0.26 OD | 19/19 | 117/117 | Reference | Reference |
|
| ||||||
| EHMIL serumb HEV IgM | ||||||
| (1) No adjustment | 136 | 2857 MFI | 18/19 | 115/117 | 94.7% | 98.3% |
| (2) Ratio | 136 | 4.3 | 18/19 | 115/117 | 94.7% | 98.3% |
| (3) Difference | 136 | 1437 MFI | 18/19 | 115/117 | 94.7% | 98.3% |
|
| ||||||
| EHMIL serumb HEV IgA | ||||||
| (1) No adjustment | 136 | 641 MFI | 18/19 | 116/117 | 94.7% | 99.1% |
| (2) Ratio | 136 | 11.4 | 19/19 | 115/117 | 100.0% | 98.3% |
| (3) Difference | 136 | 543 MFI | 19/19 | 116/117 | 100.0% | 99.1% |
|
| ||||||
| EHMIL salivac HEV IgA | ||||||
| (1) No adjustment | 134d | 571 MFI | 7/19 | 113/115 | 36.8% | 98.3% |
| (2) Ratio | 134d | 2.3 | 17/19 | 113/115 | 89.5% | 98.3% |
| (3) Difference | 134d | 238 MFI | 13/19 | 114/115 | 68.4% | 99.1% |
a
Five serum samples were classified as “borderline” (neither positive nor negative) by Wantai HEV IgM assay and were therefore excluded from the sensitivity and specificity analysis.
b
Serum samples were diluted 1:1000 for EHMIL assay;
c
saliva samples were diluted 1:8 for EHMIL assay;
d
two saliva samples were missing.
OD=optical density; MFI=Median fluorescence intensity.
Note: HEV antigen used in EHMIL assays is fused with GST tag. Cut-off value to calculate sensitivity and specificity of EHMIL HEV assays determined using (1) only HEV specific signal, (2) ratio of HEV to GST specific signal, (3) difference between HEV and GST specific signal.