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)

The capsid proteins of hepatitis A virus (HAV) were expressed as fusion proteins of beta-galactosidase in E. coli using the expression vector lambda gt11. Four fusion proteins were stably expressed and used to immunize rabbits to obtain mono-specific antisera. The antisera were unable to neutralize viral infectivity or react with HAV by radioimmunoassay. Three of the antisera were able to recognize HAV antigens in infected BS-C-1 cells by immunofluorescence and denatured capsid proteins by immunoblot analysis. The antisera were used to investigate the migration of the capsid proteins in gels by immunoblot analysis using standard SDS-PAGE conditions and in gels containing urea. The migration of VP1 and VP3 correlated with their molecular weights predicted from the nucleotide sequence and was consistent in either the presence or absence of urea. However, VP2 migrated with an apparent molecular weight significantly higher than the predicted value and, in gels containing urea, migrated as a doublet. It is proposed that the upper band of this doublet represents VP0, the proteolytic precursor of VP2 and VP4. The relative molecular mass (Mr) of VP4 was estimated to be less than 1 kDa, which is substantially lower than the 2.5 kDa predicted from the nucleotide sequence.
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PMID:Characterization of hepatitis A virus capsid proteins with antisera raised to recombinant antigens. 165 50

ELISA detection of a hepatitis-E-virus-associated antigen (HEV-AAg) in stools was reappraised for its possible interference with a new Fab-binding factor, termed protein Fv, released during infectious hepatitis. Transaminase elevation, HEV-AAg discharge and Fv leakage appeared simultaneously in a Cercopithecus monkey inoculated with infected stools. Labelled normal, or immune human IgG, were compared with pre- and post-inoculation simian IgG, for HEV-AAg and Fv detection. Coated normal and patient human IgM were also compared to pre- and post-inoculation simian IgM in HEV-AAg and Fv capture assays. Simian IgM and beta-galactosidase-labelled simian IgG minimized Fv interference and appeared to be the best adapted system for HEV-AAg detection. Nevertheless, Fv was still the cause of false-positive interpretations in some cases; therefore adsorption with monoclonal IgM was required to ensure HEV specificity. The improved test was performed on stools from 30 Senegalese patients hospitalized for various sporadic attacks of viral hepatitis. HEV-AAg was detected in 6 out of 30 cases and no positivity was observed in patients suffering from hepatitis due to HAV, HBV, cytomegalovirus or Epstein-Barr virus. The specificity of the assay was confirmed by inhibition experiments with the sera from HEV-infected patients. Hence, this inhibition assay can also be used to detect serum antibodies to HEV-AAg.
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PMID:Hepatitis-E-virus-associated antigen: improved detection in stools by protein Fv removal. 166 35

A hepatitis A virus cDNA fragment coding for the viral proteinase 3C was expressed as a chimeric protein fused in-frame to the C-terminus of beta-galactosidase. Following induction of the lac Z promoter, polypeptides of 150, 28, 26, and 16 kDa, all of which carry 3C antigenicity, were produced. The 28- and 26-kDa proteins were identified as autoproteolytic products of the fusion protein by determination of their N-terminal amino acid sequence. The 16-kDa protein arises from internal initiation. Following substitution of the 37 amino acids at the C-terminus of 3C, the autolytic activity was no longer observed. The recombinant proteinase did not show trans-activity when recombinant proteins of the P1 or P2 region were used as substrates. Antisera directed against recombinant 3C could not detect 3C or its precursors in HAV-infected cells.
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PMID:Autoproteolytic cleavage of recombinant 3C proteinase of hepatitis A virus. 185 Sep 33

Six overlapping genomic regions of capsid proteins VP1 and VP3 of hepatitis A virus (HAV) inserted into the expression vectors pBD or pUR respectively expressed beta-galactosidase-HAV fusion proteins. The recombinant proteins were poorly soluble so they were difficult to detect by human anti-HAV sera in radioimmunoassay, but the fusion proteins dissolved in sodium dodecyl sulfate reacted with human and rabbit anti-HAV-positive sera in immunoblots. Antisera against VP1 and VP3 recombinant proteins reacted with the respective structural proteins of HAV in immunoblots. Two recombinant proteins, one including the first 120 amino acids of the N-terminus of VP1 and the other containing all of VP1 except for the first 60 N-terminal amino acids, induced a transient neutralizing antibody response in rabbits. Antisera directed against other regions of VP1 and VP3 neither neutralized viral infectivity nor recognized native virus in a competitive radioimmunoassay. However, when immunized animals were challenged with a sub-immunogenic dose of HAV, all animals responded with stable virus-neutralizing antibodies.
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PMID:Recombinant proteins VP1 and VP3 of hepatitis A virus prime for neutralizing response. 217 73

Research has been carried out in order to clarify the chemical nature of cell receptors interacting with a fast growing strain of hepatitis A virus (HAV) producing a cytopathic effect on Frp/3 cells. Cell surface susceptibility to HAV attachment has been studied after treatment with enzymes acting on different chemical groupings. Results obtained showed a lowering of cell susceptibility to HAV infection following the action of phospholipase A2, phospholipase C, trypsin and beta-galactosidase. These data suggested that phospholipids, proteins and galactose participate to the cellular receptorial area for HAV.
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PMID:Study of the chemical nature of Frp/3 cell recognition units for hepatitis A virus. 302 55

The ability to rearrange membranes is a unique feature of nonstructural proteins 2B, 2C, and 2BC of some picornaviruses. To analyze in detail membrane binding of the respective proteins of hepatitis A virus (HAV), they were transiently expressed in the vaccinia/T7 system, and their effect on membrane permeability was studied using beta-galactosidase as reporter. Although 2C had no effect, the significantly increased reporter activity observed in the extracellular space of 2B- and 2BC-expressing cells points to a specific effect of HAV proteins 2B and 2BC on membrane permeability. In biochemical fractionation studies, HAV 2C and 2BC showed properties of intregral membrane proteins, whereas 2B was associated with membranes as a peripheral protein. Proteinase 3C-mediated cleavage of precursor 2BC in vivo was most efficient when the enzyme was coexpressed in its precursor forms P3 or 3ABC, which both include the membrane-anchoring domain 3A. 3ABC showed the same solubility pattern as 2BC, suggesting that colocalization of 2BC and 3ABC might be required for the efficient liberation of 2B and 2C and occurs on membranes that have been proposed as the site of viral RNA replication.
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PMID:Membrane permeability induced by hepatitis A virus proteins 2B and 2BC and proteolytic processing of HAV 2BC. 987 31