HBc and HBe antigenicity and DNA-binding activity of major core protein P22 in hepatitis B virus core particles isolated from the cytoplasm of human liver cells

Abstract

Highly purified hepatitis B virus core particles were obtained in large amounts from the cytoplasm of infected human liver cells. This DNA polymerase-negative core preparation had only hepatitis B core antigen-specific antigenicity and showed a surprising stability. Two forms of a single protein of 22,000 molecular weight, P22, were resolved electrophoretically; the slower moving species, P22a, appeared to be a reduced form of the protein, and the faster moving species, P22b, could have represented a conformational isomer containing an intramolecular disulfide bond(s). The immunological properties and DNA-binding activity of the reduced form, P22a, were examined following separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by transfer onto nitrocellulose membranes (Western blotting). We found that the hepatitis B virus C gene protein shared the antigenic site responsible for both hepatitis B core and e antigen reactivity. We also demonstrated that the core protein(s) bound specifically the genomic hepatitis B virus DNA in comparison with a plasmid DNA (pBR322). This last observation was further substantiated by a radioimmunological method. P22a was also found to be phosphorylated in vitro by the endogenous protein kinase activity, copurified with the hepatitis B core antigen particles. These findings suggest that P22 is a multifunctional protein which is incorporated into core particles within the cytoplasm of the host cell before DNA encapsidation. A critical role of this protein in hepatitis B virus assembly is suggested.

Detection of an RNase H activity associated with hepadnaviruses

“…The RNase H activity at 34 to 36 kDa was located just behind and in contact with a dark band identified as core protein by its characteristic size and prominence in core preparations (37,42,48). Its appearance as a dark band in this assay is consistent with its property of binding nucleic acid moieties (34,39). These results indicate that the major RNase H activity is efficiently renatured after the sample is boiled in SDS.…”

Hepatitis B virus pre-S gene-encoded antigenic specificity and anti-pre-S antibody: Relationship between anti-pre-S response and recovery

“…Binding of these antigens on pHSA-coated beads served as a control in these experiments. In complementary experiments, we showed that our reference preparations were not bound on the beads coated with purified anti-HBc (14) or normal human IgG, and that anti-HBe present also on the solid phase was not involved in the reaction for pre-S epitopes. Digestion of the reference preparation of recombinant The polystyrene beads were coated with IgG fractions isolated from sera of two patients recovering from acute type B hepatitis and containing anti-pre-S activity or coated with pHSA.…”

RNA-binding proteins of coronavirus MHV: Detection of monomeric and multimeric N protein with an RNA overlay-protein blot assay

“…Oligomeric nucleic acid-binding proteins appear to be common virus structural components. The nucleocapsid of HSV-2 contains a protein of mol wt 350K which consists of two disulfide-linked proteins (Zweig et a& 1979), and disulfide-bonded multimeric forms of DNA-binding proteins of vaccinia and hepatitis B viruses have recently been detected (Ichihashi et uL, 1984;Petit and Pillot, 1985).…”

“…A sensitive nucleic acid overlay-protein blotting method (Bowen et al, 1980) has been useful for the initial identification of both DNA-binding proteins (Blair and Honess, 1983;Braun et &, 1984;Ichihashi et al, 1984;Roberts et d, 1985;Petit and Pillot, 1985) and RNA-binding proteins of Rous sarcoma virus (Bowen et al, 1980;Merit et ai, 1984) and ribosomes (Rozier and Mache, 1984). We have adapted the RNA overlay-protein blot assay (ROPBA) to detect the virus-specific RNA-binding proteins in coronavirus infected cells and virions.…”