Fig. 2.

Mechanism of the neutralizing activity of 8D6. a Immunohistochemistry results indicate that 8D6 neutralized HCV during the re-attachment steps. For the pre-attachment assay, 10 µg/ml mAbs were incubated with HCVcc for 1 h before the mixture was added to the cells. For the post-attachment assay, HCVcc was first incubated with Huh7.5.1 cells for 4 h at 37 °C to allow virus entry. Cells were washed to remove unattached virus followed by adding 8D6 to the medium. The anti-influenza virus mAb 3E1 was used as an isotype control. The cells were incubated at 37 °C for 72 h, followed by methyl alcohol fixation and NS5A immunostaining. pre, pre-attachment; post, post-attachment. b Statistical analysis and a graph were used to quantify the virus plaques that escaped 8D6 neutralization. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, NS, not significant (two-tailed Student’s t test). c The effect of 8D6 on the binding of E2 to CD81 was studied by ELISA. AR3A served as a positive control, and 3E1 served as the isotype control. The data are representative of at least three independent experiments