Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleocapsid of hepatitis B virus (HBV) is an efficient immunogen in activating T cells to produce interferon-gamma (IFN-gamma) in patients with chronic HBV infection. We investigated hepatitis B core antigen (HBcAg)-specific T cell recognition, which seems to be implicated in the pathogenesis of chronic liver disease. IFN-gamma production by peripheral-blood mononuclear cells of patients with chronic HBV infection [25 patients with chronic active hepatitis (CAH) and 14 asymptomatic carriers of HBV (ASCs)] was measured by an enzyme-linked immunosorbent assay. P19 polypeptide, which is derived from recombinant HBcAg particle (rHBcAg), increased IFN-gamma production in patients with CAH, but its effect was weaker than that of rHBcAg. P19 had no stimulating effect on T cells from ASCs. The fine specificity of T cell recognition of HBcAg was examined using 8 kinds of synthetic peptides. T cells from the patients who responded against P19 polypeptide recognized the sites within the common sequences of HBcAg and HBeAg (p72-90, P90-99, P108-122 and P126-146). These results suggest that HBcAg and P19 are cross-reactive at the T cell level, and that these T cells recognize the sites within the common sequences of HBcAg and HBeAg in HBV-infected patients.
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PMID:Gamma-interferon production in response to hepatitis B core protein and its synthetic peptides in patients with chronic hepatitis B virus infection. 170 82

The capsid protein of hepatitis B virus (P19) is made of 183 amino acids and carries the antigenic sites of hepatitis B core antigen (HBcAg) and hepatitis B e antigen (HBeAg) on the amino-terminal domain. The carboxyl-terminal domain of P19 (amino acids 150-183) is arginine-rich (47%) and faces the interior of the nucleocapsid for the binding with DNA. Monoclonal antibody was raised against an antigenic site on this protamine-like region of P19, which was distinct from HBcAg or HBeAg sites, and the novel antigenic site(s) was provisionally designated as hepatitis B inner core antigen (HBicAg). When P19 in a low concn (150 ng/ml) was immobilized on the solid surface, HBicAg sites were preserved, while HBcAg or HBcAg sites were no longer available on it. This allowed the detection of antibodies against HBicAg (anti-HBic), by sandwiching them between immobilized P19 and anti-IgG labeled with horseradish peroxidase. Anti-HBic was detected in sera from HBsAg carriers, typically those seropositive for antibody to HBeAg. A synthetic arginine-rich decapeptide, with a sequence of Arg-Arg-Arg-Gly-Arg-Ser-Pro-Arg-Arg-Arg, representing amino acids 150-159 of P19 and conserved in the majority of reported hepatitis B virus, absorbed the activity to bind with P19 in seven (44%) out of 16 sera containing anti-HBic. These results indicate that the decapeptide carries an HBicAg epitope and the remaining amino acid sequence of the arginine-rich carboxyl terminal domain (160-183) may be responsible for the other HBicAg epitopes.
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PMID:Antigenic sites on the arginine-rich carboxyl-terminal domain of the capsid protein of hepatitis B virus distinct from hepatitis B core or e antigen. 246 50

The core of Dane particles, the presently accepted hepatitis B virus nucleocapsid, contains two polypeptides (P19 and P45) with the antigenicity of hepatitis B e antigen (HBeAg). The antigenicity of hepatitis B core antigen (HBcAg) was not detectable in either of them by the conventional in vitro assay methods, despite the fact that both of these polypeptides were derived from the core of Dane particles. When a rabbit had been immunized with the purified preparation of P19 emulsified in complete Freund's adjuvant, however, humoral antibody against HBcAg was produced in addition to the antibody against HBeAg. Amino acid analysis of P19 disclosed a high content of arginine (12.9%), leucine (11.9%), serine (10.3%) and proline (10.2%). The amino acid composition of P19 was found to be strikingly similar to the composition of the 183 amino acid sequence deduced from the sequence of hepatitis B virus DNA which has been presumed to be encoding HBcAg. We conclude that both HBeAg and HBcAg are antigenic determinants borne by the major polypeptide (P19) constituting the core of Dane particles.
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PMID:Demonstration of the immunogenicity of hepatitis B core antigen in a hepatitis B e antigen polypeptide (P19). 617 55

Hepatitis B e antigen (HBeAg) constitutes the nucleocapsid of hepatitis B virus (HBV) and occurs in association with plasma proteins, particularly with IgG, in the serum of persons infected with the virus. A polypeptide with an approximate m.w. of 15,500 (P15.5) is obtained either from HBeAg in the serum or from the nucleocapsid of HBV. P15.5 preparations from serum and virus resembled closely each other in the amino acid composition. The C-terminus amino acid sequence of P15.5 from serum was determined to be -Thr-Thr-Val-Val, whereas that from the virus ended with -Thr-Thr. The same sequence of four amino acid residues was found on the gene coding for the nucleopeptide of hepatitis B virus with a molecular size of 19,000 daltons (P19). P15.5 identified on the nucleotide sequence of P19 was composed of 149 amino acid residues with a calculated molecular size of 16,770 daltons. The gene coding for P19 had two -Asp-Pro-connections. By splitting these connections in P19 and P15.5 preparations with formic acid, smaller polypeptides were obtained with sizes predicted from the nucleotide sequence and with the N-terminus amino acid of proline as expected. One of two monoclonal antibodies raised against the core of Dane particles (HBcAg) bound with P15.5 preparations purified from serum and HBV. The IgG fraction from a human serum containing antibodies to HBcAg but not to HBeAg bound with P15.5 also. On the basis of the results obtained, the IgG molecules associated with P15.5 in the serum of persons infected with HBV may well represent the antibodies against HBcAg with limited specificities.
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PMID:Immunochemical structure of hepatitis B e antigen in the serum. 618 3

Hepatitis B e antigen (HBeAg) occurs in the serum of individuals infected with hepatitis B virus both free and in association with IgG. Utilizing a succession of steps involving salt precipitation, affinity chromatography, ion-exchange chromatography and isoelectrofocusing, we isolated free and IgG-bound forms of HBeAg from the sera of infected individuals with an overall gain in specific activity of 3000-fold and 540-fold, respectively. Polypeptide profiles of purified HBeAg preparations were studied by SDS-polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol. Both free and IgG-bound preparations revealed polypeptides with mol. wt. of 15500 (P15.5) and 16 500 (P16.5), and HBeAg activity was detected corresponding to their positions. The HBeAg polypeptides (P15.5/16.5) derived from sera were physicochemically different from the two polypeptides with HBeAg activity (P19 and P45) liberated from Dane particle cores by the conventional method involving incubation with Nonidet P40 and 2-mercaptoethanol. However, when core particles were prepared in the presence of a proteolytic enzyme, in addition to Nonidet P40 and 2-mercaptoethanol, they gave rise to HBeAg polypeptides with mol. wt. of 31000 (P31) and 15 500. Furthermore, P31 split into P15.5 when heated at 100 degrees C for 2 min. On the basis of these results, P15.5 may be assumed to be the essential polypeptide bearing HBeAg activity in the serum and also in Dane particles.
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PMID:Hepatitis B e antigen polypeptides isolated from sera of individuals infected with hepatitis B virus: comparison with HBeAg polypeptide derived from Dane particles. 744 Dec 14

Recombinant virus-like particles (VLPs) represent a safe and effective vaccine strategy. We previously described a stable transgenic plant system for inexpensive production and oral delivery of VLP vaccines. However, the relatively low-level antigen accumulation and long-time frame to produce transgenic plants are the two major roadblocks in the practical development of plant-based VLP production. In this article, we describe the optimization of geminivirus-derived DNA replicon vectors for rapid, high-yield plant-based production of VLPs. Co-delivery of bean yellow dwarf virus (BeYDV)-derived vector and Rep/RepA-supplying vector by agroinfiltration of Nicotiana benthamiana leaves resulted in efficient replicon amplification and robust protein production within 5 days. Co-expression of the P19 protein of tomato bush stunt virus, a gene silencing inhibitor, further enhanced VLP accumulation by stabilizing the mRNA. With this system, hepatitis B core antigen (HBc) and Norwalk virus capsid protein (NVCP) were produced at 0.80 and 0.34 mg/g leaf fresh weight, respectively. Sedimentation analysis and electron microscopy of transiently expressed antigens verified the efficient assembly of VLPs. Furthermore, a single replicon vector containing a built-in Rep/RepA cassette without P19 drove protein expression at similar levels as the three-component system. These results demonstrate the advantages of fast and high-level production of VLP-based vaccines using the BeYDV-derived DNA replicon system for transient expression in plants.
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PMID:A DNA replicon system for rapid high-level production of virus-like particles in plants. 1930 55