We have studied the properties of HBeAg secreted by L cells transformed with recombinant plasmid containing prscore and core genes of the hepatitis B virus. The HBeAg secreted by transformed mammalian cells in 10% calf serum medium was found to be non-specifically associated with calf serum proteins, which may be the α1 and (3 globulins. The molecular weight of HBeAg associated with serum proteins was about 60-80KD. It was completely precipitated by 50% ammonium sulfate. After disassociation by SDS-PAGE, th...