Fig. 3.

Optical density (OD) values of hepatitis E patient samples and negative control sera in HEV-A4 p239 and HEV-C1 p241 IgG EIAs.

(A) ODs of HEV RT-PCR and Wantai IgG negative donor sera, HEV-A RT-PCR-positive patient sera/plasma, and HEV-C1 RT-PCR positive patient sera/plasma run in parallel in HEV-A4 p239 and HEV-C1 p241 EIAs. Red line represents background thresholds of respective EIAs (0.388 and 0.235 for HEV-A4 p239 and HEV-C1 p241 EIAs, respectively). (B) Two-dimensional scatter plot of HEV-A4 p239 and HEV-C1 p241 OD values showing mostly distinct clusters formed by donor sera, HEV-A RT-PCR positive, and HEV-C1 RT-PCR-positive samples. The cluster formed by the seronegative donor sera is encircled and includes four HEV-A and two HEV-C1 RT-PCR-positive samples that did not show a detectable humoral response in either EIA. (C) Receiver operator characteristic (ROC) curves for establishing cut-offs for individual EIAs and OD_{HEV-A4 p239}/OD_{HEV-C1 p241} (‘A/C ratio’). The blue line is the ROC curve for the HEV-A4 p239 EIA in distinguishing HEV-A and non-HEV-A samples. The red line is the ROC curve for the HEV-C1 p241 EIA in distinguishing HEV-C1 and non-HEV-C1 samples. The green line is the ROC curve for A/C ratios for distinguishing HEV-A and HEV-C1 RT-PCR positive samples. Areas under the curve (AUC) are presented. HEV-A, Paslahepevirus balayani; HEV-C1, Rocahepevirus ratti; OD, optical density.