Some Properties of Hepatitis B Core Antigen Isolated from Serum of Infected Humans

Abstract

The nucleocapsid of Dane particles (= hepatitis B core antigen; HBcAg) was isolated from human sera either positive or negative for e-antigen (HBeAg) — an apparent marker for the level of infectious hepatitis B virus in serum. HBcAg from the HBeAg-positive serum pool consisted of two distinct populations of particles, one with a buoyant density (d) of 1.358 g/ml and a sedimentation coefficient (s_{20, w}) of ≈ 110, and another with d = 1.28 to 1.30 g/ml and s_{20, w} ≈ 70. Only the latter type of particles was isolated from an HBeAg-negative serum pool. HBcAg was labelled with ¹²⁵I-p-hydroxyphenylpropionic acid N-hydroxysuccinimide ester, dissociated and analysed by polyacrylamide gel electrophoresis. One major and one minor polypeptide with apparent mol. wt. of 16000 ± 500 and 68000, respectively, were detected. Another component having the properties of a glycolipid with a mol. wt. in the order of 10³ was observed. After isoelectric focusing, HBcAg was recovered in fractions with a pH between 4.0 and 5.8, suggesting heterogeneity in isoelectric points.