Figure 4. HBV neutralizing activities of mouse anti-HBsAg mAbs evaluated using HBV replication system in HepaRG cells. Decreased virus concentrations, as indicated with HBeAg levels, were observed with increasing level of mAbs. Control mouse IgG showed no impact on the virus replication. The neutralizing activities of 5F11 and 42B6 were comparable (IC₅₀ ~16 ng/mL), both having higher neutralization activity than E2A9. All of 3 epitopes, as recognized by these mAbs, are essential for HBV infection, and likely for maintaining the structure of HBsAg.