OBJECTIVETo develop human recombinant neutralizing IgG monoclonal antibodies to hepatitis A virus (HAV) by baculovirus expression system.

METHODSThe heavy and light chain genes of two human-derived neutralizing Fab antibodies to HAV were cloned into baculovirus expression vector Pac-kappa-Fc and Pac-L-Fc, and further expressed in insect cells as IgG antibodies. The IgG products were purified and well characterized.

RESULTSThe baculovirus expressed McAb HAFc16 fully retained the specificity of binding to hepatitis A virus and the competition with mouse anti-hepatitis A virus McAb using ELISA. The viral neutralization assay in vitro demonstrated the retention of antibody function after expression of the human antibody in insect cells. The other expressed antibody HAFc78 also has the neutralizing activity but it is directed against different epitopes of HAV when compared with HAFc16.

CONCLUSIONThe recombinant baculovirus/insect cells expressed human neutralizing IgG antibodies to hepatitis A virus retained all biological functions specific for hepatitis A virus. The results provided the possibility of using these antibodies to rapidly protect high risk or early exposure populations from hepatitis A virus infection.