Figure 2: HCV ELISA for urea-denatured HCV core mutants. The urea-denatured HCV core antigens (100 μL of 4 μg/mL per well) were used to coat the microplate for the detection of anti-HCV antibody of BBI panel (a) and GBC inhouse panel (b). The absorbance data were compiled statistically as S/Co value (S: sample value; Co: cut-off value). The cut-off value was calculated as the negative control OD plus positive control OD divided by 4 (). The positive samples (i.e., S/Co > 1, marked as open circle, lot number HCV10165-6~9) could be clearly separated from the negative samples (i.e., S/Co < 1, marked as closed circle, lot number HCV10017-1~7, HCV10026-1~5, HCV10058-1~3) of BBI panel. In Figure 2(b), the primary antibodies used are sequentially diluted in 10-fold order from 10x to 70x of the PC (positive control) and NC (negative control). Co value was calculated by the average OD values of NC and 20x PC. The data are marked as • (10x), ∘ (20x), ▾ (30x), ▽(40x), ■ (50x), □ (60x), ♦ (70x), and (negative control).