Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoclonal antibodies (McAb) specific for the pre-S region of the hepatitis B virus (HBV) envelope protein were prepared using HBV particles of hepatitis B surface antigens (HBsAg) as immunogens. The antibodies reacted in Western blot analyses and in ELISA with pre-S2 sequences of the HBV envelope protein. Pepsin or protease V8 treatment of the antigen abolished reactivity. The fine specificity of one of the McAb (F376) was established by immunoassays using synthetic peptides and a pre-S2-beta-galactosidase fusion protein expressed in E. coli. The shortest peptide recognized by F376 is demarcated by residues pre-S(132) at the N-terminal and pre-S(140)-pre-S(145) at the C-terminal. The corresponding amino acid sequence (for HBV subtype adw2) is: QDPRVRGLY(LPAGG). Additional amino acid residues at the N-terminal, and possibly at the C-terminal ends contribute to the binding of McAb, probably due to conformational influences. The McAb was applied to immunoassays of pre-S2 sequences in purified HBsAg and in human sera containing HBsAg.
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PMID:Characterization of monoclonal antibodies specific for the pre-S2 region of the hepatitis B virus envelope protein. 243 Dec 99

DNA from the pre-S region of the duck hepatitis B virus (DHBV) genome was inserted into an open reading frame vector designed to give high-level expression in Escherichia coli. The resulting fusion protein contained the first 8 amino acids of beta-galactosidase, 86 amino acids of the DHBV pre-S region, and 219 amino acids of chloramphenicol acetyltransferase at the C terminus (beta-gal:pre-S:CAT). Rabbit antiserum against purified beta-gal:pre-S:CAT was used to identify pre-S-containing polypeptides in DHBV particles by Western blotting. A dominant species of 36 kilodaltons (kDa) was identified. Antiserum against the major 17-kDa DHBsAg polypeptide also reacted with the 36-kDa protein. This suggests that the DHBV envelope gene polypeptides share the same carboxyl terminus, but differ in the sites from which translation is initiated. N-linked carbohydrate was not detected on either the 17- or 36-kDa envelope proteins. Anti-beta-gal:pre-S:CAT abolished infectivity of the virus in an in vitro assay. Thus, the pre-S region is exposed on the surfaces of infectious virions and may be directly involved in binding of virus to host-cell receptors.
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PMID:Characterization of a pre-S polypeptide on the surfaces of infectious avian hepadnavirus particles. 243 17

Tripartite fusion proteins comprising the nontoxic mutant protein CRM228 of diphtheria toxin (DT), the hepatitis B virus surface antigen (HBsAg), and beta-galactosidase were obtained by expression of hybrid genes from the pR promoter of bacteriophage lambda and purification by affinity chromatography. The antigenicity and immunogenicity of the individual protein constituents were analyzed. A major neutralizing epitope of DT was inactivated by the HBsAg insertion into the DT B fragment. The fusion proteins elicited antibodies reactive with 22 nm HBsAg particles. This suggests a novel approach towards the use of DT mutants as immunogenic carriers of heterologous antigens.
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PMID:Genetically engineered diphtheria toxin fusion proteins carrying the hepatitis B surface antigen. 244 98

Synthetic vaccines for viral diseases can use defined regions of viral proteins as immunogens: the peptide sequence of amino acids 141-160 of the VP1 protein of foot and mouth disease virus (FMDV) elicits virus-neutralizing antibodies to protect guinea pigs, cattle and pigs either when coupled to a carrier protein or when administered in liposomes or in incomplete Freund's adjuvant. The immune response to these peptides is much lower than that to complete virus particles and the same sequence fused to the N terminus of beta-galactosidase did not produce a more potent immunogen than synthetic peptide alone. We report here an expression system for immunogenic epitopes linked to a carrier protein, hepatitis B core antigen, to form part of a virus-like complex which can present these epitopes to the immune system at high density. The immunogenicity of these structures approaches that of FMDV particles.
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PMID:Improved immunogenicity of a peptide epitope after fusion to hepatitis B core protein. 244 37

Mouse monoclonal IgG1 specific for hepatitis B surface antigen and ovine polyclonal antibody raised against digoxin were covalently coupled by a diazotisation method to small unilamellar vesicles (SUV) composed of equimolar phospholipid and cholesterol supplemented with 6 mol% aminophenylstearylamine (APSA). Up to 33% of the antibody used was associated with vesicles, depending on the phospholipid and the antibody type used. Antibody-coated SUV were mixed with carboxyfluorescein (CF) or beta-galactosidase to generate multilamellar dehydration-rehydration vesicles (DRV) containing CF or active enzyme. In contrast, coupling of antibodies directly to beta-galactosidase-containing DRV resulted in total inactivation of the enzyme. About 85% of the SUV-bound antibody was recovered in DRV and of this, 78-82% was exposed on the liposomal surface, possibly because of reorientation of the APSA-antibody complex during DRV formation. Antibody-coated DRV remained stable in the presence of plasma at 37 degrees C and also under storage at 4 degrees C. Further, antibody coupled to such liposomes was capable of efficient interaction with the respective antigen. The present method allows the attachment of antibodies to the liposomal surface independently of entrapment of solutes, the activity of which is thus preserved, and could be adapted to alternative coupling procedures or ligands.
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PMID:Dehydration-rehydration vesicle methodology facilitates a novel approach to antibody binding to liposomes. 271 95

A bidirectional expression vector containing both the 11KD late promoter (p11) and the presumptive 25KD early promoter (p25) was constructed. These bidirectional vectors have been applied to the expression of hepatitis B surface antigen by using one of the promoters for beta-galactosidase as the marker gene and the other one for hepatitis B surface antigen as the target gene.
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PMID:Construction and application of plasmids containing bidirectional promoters of vaccinia virus. 284 96

We have developed a procedure for the quantitation of specific DNA which employs nonradioisotopic probes and beta-galactosidase as a detector. The sample DNA was immobilized on a nitrocellulose filter paper. After the filter paper had been processed to hybridization with a biotinylated probe DNA, the paper was incubated with avidin-beta-galactosidase complex. The optimum ratio of avidin to biotinylated beta-galactosidase for preparation of a complex between the two was determined. The filter paper was punched. Each punched piece was put into a microtiter well and beta-galactosidase activity was measured using 4-methylumbelliferyl beta-D-galactosidase as a substrate. By this method, we were able to quantify as little as a few picograms of specific DNA. The application of this method for the quantitative assay of hepatitis B virus DNA in serum sample is also described. The sensitivity for the detection of the DNA by our method was practically comparable to that of the conventional radioisotopic method. The validity of our method for detection of the virus DNA was further supported by comparison with the serological data.
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PMID:A quantitative assay for the detection of hepatitis B virus DNA employing a biotin-labeled DNA probe and the avidin-beta-galactosidase complex. 309 60

A novel expression system based on coinfection of cells with two recombinant vaccinia viruses has been developed. One recombinant vaccinia virus contained the bacteriophage T7 RNA polymerase gene under control of a vaccinia virus promoter. The second recombinant vaccinia virus contained a target gene of choice flanked by bacteriophage T7 promoter and termination sequences. Maximum expression of the target gene occurred when cells were infected with 10 PFU of each recombinant virus. Although T7 RNA polymerase synthesis began shortly after infection, the target gene was not expressed until late times and was largely inhibited when DNA replication was blocked. Target gene transcripts were analyzed by agarose gel electrophoresis and had the predicted size. With this system, Escherichia coli beta-galactosidase, hepatitis B virus surface antigen, and human immunodeficiency virus envelope proteins were made. In each case, the level of synthesis was greater than had previously been obtained with the more conventional recombinant vaccinia virus expression system.
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PMID:Use of a hybrid vaccinia virus-T7 RNA polymerase system for expression of target genes. 311 59

Sequence analysis of the hepatitis B virus (HBV) genome revealed the presence of an open reading frame (ORF X) which has the potential to encode a 154-amino acid polypeptide. A fusion protein containing 145 of the amino acids encoded by ORF X and 8 amino acids of beta-galactosidase was expressed and characterized in bacterial extracts. Immunoprecipitations with the ORF X fusion protein as a radioactively labeled antigen were performed to screen sera of humans infected with HBV for the presence of antibodies against ORF X-encoded determinants (anti-X). Such antibodies were identified in 9 samples from a set of 26 sera characterized as positive for HBV surface antigen but were not found in 16 normal human sera. The data reported here demonstrate that sera from some patients with markers of HBV infection contain antibodies directed against the polypeptide encoded by ORF X. As such, these findings represent evidence that ORF X constitutes a gene, or a portion of a gene, which is expressed during HBV infection. Although there does not appear to be a direct relationship between anti-X and any individual markers of HBV infection, our data suggest that anti-X is more prevalent in HBV-positive sera containing antibodies to HBe3 antigen (anti-HBe3).
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PMID:Hepatitis B virus polypeptide X: expression in Escherichia coli and identification of specific antibodies in sera from hepatitis B virus-infected humans. 351 Mar 11

The genome of the hepatitis B virus (HBV) contains a sequence, designated X, capable of encoding a protein of 154 amino acids. To determine whether the putative protein synthesized from this region is antigenic, we examined the sera of HBV-infected patients for the ability to react with a hybrid protein that contained 133 amino acids encoded by the X region and portions of the bacterial ompF and beta-galactosidase genes. Some HBV-positive sera tested contained antibodies that specifically recognized the hybrid protein. All sera were from patients diagnosed as suffering from chronic active hepatitis. We conclude that the X region of HBV encodes a protein and that this protein is antigenic in some patients.
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PMID:Detection of hepatitis B virus X product using an open reading frame Escherichia coli expression vector. 351 47


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