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Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sedimentation of radiolabelled 22 nm hepatitis B surface antigen particles was unaffected by treatment with either trypsin or SDS alone, but combined treatment disrupted the particulate nature of the radiolabelled material. Considerable antibody binding activity by the group-specific determinant (a) was preserved after combined SDS and trypsin treatment but was released from the bulk of the radiolabelled protein; gel filtration indicated an approximate mol. wt. of 5000 to 15000 for the released antibody binding material. This material was precipitated by concanavalin A, suggesting the presence of carbohydrate. Its serological activity was remarkably resistant to boiling and to proteolytic digestion, but was partially sensitive to treatment with 0-01 M-periodate or with mixed carbohydrases and neuraminidase, and was greatly reduced by treatment with reducing agent. These data suggest that the stability of the a determinant is due to the structure of the antibody binding site itself, rather than to involvement in the quaternary structure of the particle, and that intact disulphide bonds and carbohydrate, closely related to the antibody binding site, are necessary for the full expression of serological acitivity.
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PMID:Tryptic cleavage of antibody binding sites from hepatitis B surface antigen particles. 6 23

The purpose of this study was to explore a method by which an improved immunofluorescent staining can be applied to formalin-fixed paraffin sections to demonstrate cellular or tissue deposits of immunoglobulins, complement and fibrin, and to demonstrate alpha-1-antitrypsin storage and hepatitis B antigens in liver, toxoplasma in heart, and carcinoembryonic antigens in colonic cancer. It was shown that immunohistochemical demonstration for the above mentioned antigens, but not for complement, was feasible. The paraffin sections were first treated with trypsin and the indirect staining method was used. The trypsin treatment was found to decrease the nonspecific background fluorescence through digestion of the tissue. It probably also unmasked the immunoreactive sites of viral antigens and alpha-1-antitrypsin. In general, a 2-hour digestion was satisfactory for the types of tissues examined in this study, and an optimal period of digestion could be sought to obtain the best result for a specific antigen. This method may be a useful adjuvant to histopathologic study, in which a retrospective immunohistochemical examination may be desirable.
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PMID:Application of immunofluorescent staining on paraffin sections improved by trypsin digestion. 6 99

The recombinant gene for hepatitis B core antigen (HBcAg) was cloned and expressed, and the protein was purified from Escherichia coli cultures. Purified HBcAg was tested for the effects of various physical and chemical agents on its immunoreactivity by a paramagnetic particle-based enzyme immunoassay. Recombinant HBcAg retained its immunoreactivity when heated at 70 degrees C for 60 min but was inactivated at 85 degrees C in 10 min. It was stable between pHs 5 and 10.5 but not at pHs 2 and 13.5. Treatment with sodium dodecyl sulfate (SDS), ethanol, and methanol caused a significant loss in HBcAg reactivity. The proteolytic enzymes papain and bacterial protease (type VIII from Bacillus licheniformis) degraded HBcAg significantly, but trypsin and chymotrypsin did not. The effect of combined SDS and 2-mercaptoethanol on recombinant HBcAg was an immediate loss in immunoreactivity, followed by rapid recovery to about 50% of the initial level. This level was maintained for 24 to 48 h and was followed by an almost total loss of HBcAg in about 120 h.
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PMID:Stability of the recombinant hepatitis B core antigen. 162 88

Two determinants of hepatitis B surface Ag (HBsAg), identified by mAb raised against polypeptide components, were characterized immunochemically. One was expressed on HBsAg irrespective of the four major subtypes, i.e., adw, adr, ayw, and ayr, whereas the other was subtypic but not identical to any of d, y, w, and r determinants. The common determinant was generated by a synthetic pentadecapeptide with a sequence of Thr-Thr-Ser-Thr-Gly-Pro-Cys-Lys-Thr-Cys-Thr-Ile-Pro-Ala-Gln representing amino acids 115-129 of the S gene product, and detected invariably in 366 HBsAg samples in sera from asymptomatic carriers in Japan. The activity of the S gene product, as well as the peptide (115-129), to bind with the mAb was not affected by alkylation alone, but was completely lost after reductive alkylation. The antigenic activity was lost when the S gene product was severed between Lys122 and Thr123 by trypsin. A microconformation maintained by the -Cys121-Cys124 bond, therefore, would be required for the common determinant. The other mAb identified an epitope of HBsAg that was mimicked by a synthetic tetradecapeptide with a sequence of Thr-Cys-Thr-Ile-Pro-Ala-Gln-Gly-Thr-Ser-Met-Phe-Pro-Ser, representing amino acids 123-136 of the S gene product. Among 16 HBsAg samples with known S gene sequences, 5 with Ile126 possessed this subtypic determinant, but the remaining 11 with Thr126 did not. The 5 hepatitis B virus genomes encoding the subtypic determinant differed less than 5.6% from each other in the entire nucleotide sequence, but by 8.0% or more from any of the other 11 genomes without the capacity to encode it.
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PMID:Synthetic oligopeptides bearing a common or subtypic determinant of hepatitis B surface antigen. 169 80

Cellular receptors play an important role in viral pathogenesis. Until now, there has been no reliable information on the receptor(s) for hepatitis B virus (HBV). Therefore, we attempted to identify specific receptors in human hepatocytes using an immunological approach. Anti-idiotypic (Ab2) antibodies were raised in rabbits against our monoclonal antibody (MAb1) F35.25. MAb1 F35.25 (i) recognized the hepatocyte receptor binding site on HBV (located between amino acid residues 21 and 47 of the preS1 sequence) and (ii) blocked the attachment of preS1-positive HBV particles to human hepatocytes. The presence of Ab2 antibodies in rabbit sera was determined by the ability of antisera to inhibit Id (Ab1)/antigen (HBV) recognition. Affinity-purified Ab2 IgGs to F35.25 represented an internal image for the preS1 domain 12-53. Our present studies indicate that Ab2 IgGs to F35.25 (i) recognized the membrane-associated structure of the preS1-specific HBV receptor in a HepG2 cell binding assay, as visualized by immunoenzymatic staining; (ii) strongly bound to a major 35-kDa component and to three other related proteins of 50, 43, and 40 kDa in extracts of HepG2 cells; and (iii) reacted with several soluble and membrane-associated proteins in normal human liver cells. The binding was insensitive to reduction. All preS1 binding proteins were V8 protease sensitive and endoglycosidase H resistant. The 35-kDa species was trypsin resistant and generated a band of 32 kDa by endoglycosidase F treatment. Together, our results suggest that the identified preS1-specific binding proteins may be involved in the putative complex structure of the hepatocyte receptor for HBV.
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PMID:PreS1-specific binding proteins as potential receptors for hepatitis B virus in human hepatocytes. 173 25

Circulating immune complexes (CIC) containing HBsAg and HBeAg were identified in sera of 5 out of 6 children with hepatitis B mediated membranous glomerulonephritis. CIC were precipitated from sera by 3.5% PEG, washed and subsequently analysed after acid dissociation and trypsin digestion. HBsAg, anti-HBs and albumin; HBeAg, anti-HBe and anti-HBc were recovered from the isolated complexes and these findings are discussed. Analysis of 3.5% PEG mediated precipitate of human serum proteins showed the relatively high content of IgG classical pathway complement components: C1q, C4 and C3.
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PMID:Isolation and partial characterization of circulating immune complexes in sera of children with HBV-mediated glomerulonephritis. 184 49

Hepatitis B virus precore and core proteins are related. The precore protein contains the entire sequence of the core protein plus an amino-terminal extension of 29 amino acids. The amino-terminal extension of the precore protein contains a signal sequence for the secretion of the precore protein. This signal sequence is removed after the translocation of the precore protein across the endoplasmic reticulum membrane to produce the precore protein derivative named P22. We demonstrate that both P22 and the core protein can be phosphorylated in cells. Microsomal fractionation and trypsin digestion experiments demonstrate that a fraction of phosphorylated P22 is located in the endoplasmic reticulum lumen. Phosphorylation of P22 likely occurs in the carboxy terminus, since the P22 derivative P16, which lacks the carboxy terminus of P22, is not phosphorylated. Linking the carboxy terminus of the precore-core protein to heterologous secretory and cytosolic proteins led to the phosphorylation of the resulting chimeric proteins. These results indicate that phosphorylation of P22 and the core protein is likely mediated by cellular kinases.
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PMID:Phosphorylation of hepatitis B virus precore and core proteins. 185 14

HBsAg is known to bind to human serum albumin polymerized by glutaraldehyde, human serum albumin has been found in preparations of HBsAg by several investigators. However, it is not yet known whether natural human serum albumin binds to hepatitis B virus under physiological conditions. We studied the binding between natural or recombinant HBsAg and monomeric human serum albumin by immunological, biochemical and biophysical methods. The binding capacity of 20-nm HBs spheres was variable but ranged up to six molecules HSA/sphere. A reversible binding site for human serum albumin was exclusively localized in the preS2 domain, whereas the S domain was inactive in vitro. Human serum albumin copurified with HBsAg of human origin during gel chromatography or sucrose-gradient centrifugation. This human serum albumin was monomeric in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The preS2-bound part of the human serum albumin could be removed from HBsAg by high-salt, such as CsCl centrifugation, but another part could only be removed by treatment with a disulfide cleaving reagent. Most of this covalently bound human serum albumin was retained at the HBsAg particle after complete cleavage of medium-sized HBs protein with trypsin. This indicates a second way in which albumin binds irreversible to cysteine(s) of the small HBs protein (SHBs, P24 and GP27).
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PMID:Interaction between hepatitis B surface proteins and monomeric human serum albumin. 216 67

The diagnostically important surface antigen pre-S2 of hepatitis B virus was produced in large amounts in the periplasmic space of Escherichia coli. The DNA fragments (pre-S2) coding the pre-S2 antigen were tandemly duplicated or triplicated and ligated in the same reading frame to a fragment containing the promoter and the signal sequence of the alkaline phosphatase-coding gene (phoA) of E. coli. Further, a DNA fragment (bla) coding mature beta-lactamase was joined to the region coding the C terminus of the pre-S2 repeat to stabilize the gene product. Upon induction of the phoA-(pre-S2)3-bla fusion gene, the fusion protein was produced at up to 30% of the total cellular protein. Fractionation of the cellular components and trypsin accessibility of the product showed that the antigen was secreted in the periplasm and formed inclusion bodies there. The signal sequence of alkaline phosphatase was found to be correctly processed in E. coli.
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PMID:Production and secretion in Escherichia coli of hepatitis B virus pre-S2 antigen as fusion proteins with beta-lactamase. 227 30

To identify further the surface proteins of the native virus, hepatitis B virus (HBV) particles purified from HBe antigen (Ag)-positive human sera were used as immunogens to produce murine monoclonal antibody (MAb)-secreting hybridomas. The specific binding of antibodies to the HBV envelope (env) proteins was determined in indirect radioimmunoassay and by Western blot analysis. Six MAbs directed against major hepatitis B surface antigen (HBsAg) recognized conformational epitopes on S proteins (P24s/GP27s). Three preS2-specific MAbs reacted with the middle env proteins (GP33s/GP36s) in the 22 nm HBsAg spherical particles. One MAb, F222, was found to react specifically with the two very large (VL) HBV surface proteins with Mr 54K and 66K. The epitope recognized by F222 was located on the protruding N terminus which, in the assembled virus particles, was readily split off by trypsin or V8 protease treatment. The presence of these VL proteins appeared to correspond to the presence of the large env proteins (P39s/GP42s). The data described here indicate that F222 probably recognized an assembled topographic site which could be involved in virus entry into hepatocytes. Moreover, our results suggest that the preS-coded part of the HBV env proteins, which is sensitive to proteases in vitro, could be unstable in vivo and stabilized by immunoglobulins.
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PMID:Antigenic mapping of the surface proteins of infectious hepatitis B virus particles. 244 3


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