A thirty-year man presented with nausea, fever and jaundice of 5 days duration. The biochemical tests revealed a bilirubin of 6.7 mg/dl (conjugated 5.0 mg/ dl) with SGOT/SGPT(AST/ALT) of 1230/900 IU/ ml. The serological tests showed presence of HBs Ag. , IgM anti-HBc and HbeAg. The most likely diagnosis is -