Production of monoclonal antibodies against hepatitis E virus capsid protein and evaluation of their neutralizing activity in a cell culture system

Nine murine monoclonal antibodies (mAbs) generated against a recombinant ORF2 protein (amino acids 111–660) of a genotype 4 hepatitis E virus (HEV) strain recognized four sets of epitopes by pairwise competitive ELISA. One mAb (H6225) was able to capture HEV efficiently regardless of genotype and was tested for its ability to neutralize a genotype 3 HEV strain (JE03-1760F) in a recently developed cell culture system for HEV in a hepatocarcinoma cell line (PLC/PRF/5). When PLC/PRF/5 cells were inoculated with HEV (4.0 × 10⁵ or 4.0 × 10⁶ copies/ml) incubated with 100 μg/ml of a negative control mAb, HEV RNA in the culture medium continued to be detectable after day 14 or 12 post-inoculation (dpi), respectively. However, when cells were inoculated with the two distinct concentrations of HEV that had been mixed with 100 μg/ml of H6225, the harvested culture supernatants were negative for HEV RNA throughout the 60-day observation period. Upon prior mixing of the virus with 10 μg/ml of H6225, HEV RNA in culture supernatant continued to be undetectable until 46 or 28 dpi, respectively. In conclusion, one mAb (H6225) against HEV capsid protein that can efficiently neutralize HEV in vitro was obtained in the present study.