Immunological and Morphological Properties of HBeAg Subtypes (HBeAg/1 and HBeAg/2) in Hepatitis B Virus Core Particles

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Abstract
Summary A polypeptide of 21500 mol. wt., structurally associated with hepatitis B virus core particles, was shown to have two kinds of HBeAg antigenicity (HBeAg/1 and HBeAg/2). This was revealed by transferring a single core peptide from polyacrylamide gels to nitrocellulose sheets (Western blotting), which reacted with anti-HBeAg/1 and anti-HBeAg/2. Selective discrimination of the two HBe antigens was achieved by radioimmunoassay (RIA). When highly purified core particles were incubated at 37°C in a 0.1% SDS-0.1% 2-mercaptoethanol solution, only HBeAg/1 was released after 5 min incubation and the release of HBeAg/2 occurred only after prolonging incubation for 30 min. The course of degradation was also detected by CsCl density gradient centrifugation. These results indicate that HBeAg/1 is less closely associated with core particles than is HBeAg/2. Electron microscopy showed that the core particles from which HBeAg/1 was removed were more labile than the original preparation when incubated at 56 °C in aqueous solution, or at 37 °C in Sarkosyl solutions; when placed in 1 m-NaCl or -CsCl solution, the particles swelled to a larger diameter than untreated cores.