Characterization of hepatitis B e antigen from human breast milk.
: Hepatitis B e antigen (HBeAg) but not surface antigen (HBsAg) was detected in 20% of the milk samples taken from HBsAg carrier mothers by radioimmunoassay. The density of milk e antigen particles was peaked at 1.32 g/ml in CsCl gradient ultracentrifugation. HBeAg was found in 1.33 M and 3.24 M (NH4) 2SO4 precipitates from breast milk but neither of HBeAg in both precipitates showed exactly identical with serum-derived e antigen. Five bands of polypeptides with molecular weight of 8,000, 21,500, 37,000, 53,000 and 68,000 daltons were seen after polyacrylamide gel electrophoresis from the milk e antigen. In addition, the IgA was shown significantly high in HBeAg positive milk.