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)

Exposure to hepatitis C virus (HCV) and its effect on ALT levels was studied in 35 transfusion dependent cases of thalassaemia major. Twenty-one (60%) cases were anti HCV positive and also showed raised Alanine Transaminase (ALT) levels. Of 14 anti HCV negative, Hepatitis B Surface Antigen (HBs Ag) negative seven showed raised ALT levels, indicating the chances of acute viraemia. Thus there is an urgent need to start anti HCV screening on all blood donations.
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PMID:Prevalence of antibody to hepatitis C virus in Pakistani thalassaemics by particle agglutination test utilizing C 200 and C 22-3 viral antigen coated particles. 871 23

In view of the high antigenic variability of human immunodeficiency virus type 1 (HIV-1), a vaccine against AIDS must induce an immune response to epitopes as invariable as possible among the various virus strains and clones. Previously the highly conserved six amino acid sequence Glu-Leu-Asp-Lys-Trp-Ala (ELDKWA) from gp41, defining the epitope of the human MAb 2F5, was shown to elicit HIV-1-neutralizing antibodies when presented on haemagglutinin of influenza virus. We investigated the immunogenic potential of the MAb 2F5 epitope and two of its major escape epitopes as internal fusions to the hepatitis B virus (HBV) surface antigen (HBsAg). Recombinant HBsAg-HIV proteins produced in the methylotrophic yeast Pichia pastoris self-assembled into 22 nm lipoprotein particles. Mice immunized with these particles developed an anti-HBsAg immune response in a range that is considered to be protective against HBV infection in humans. More importantly, antisera had extremely high titres of antibodies reactive with a structurally flexible form of the HIV-1 epitope, whereby strong cross-reactivity with the escape variants of the epitope was observed. Although HIV-1 gp 160 and the ectodomain of gp41 containing the epitope were significantly recognized, the antisera failed to neutralize HIV-1 in vitro. These data, together with those on the haemagglutinin-ELDKWAS fusion suggest that the ability of the MAb 2F5 epitope to induce neutralizing antibodies depends on the molecular context in which it is presented. Therefore, further characterization of secondary and tertiary structure requirements of the epitope is indispensable for the full exploitation of its potential as a vaccine component.
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PMID:Immunogenic presentation of a conserved gp41 epitope of human immunodeficiency virus type 1 on recombinant surface antigen of hepatitis B virus. 881 Sep 96

It has been hypothesized that antibody induced by Plasmodium falciparum circumsporozoite protein vaccine would be effective against endemic human malaria. In a malaria endemic region of Kenya, 76 volunteers, in 38 pairs sleeping adjacently, were immunized with subunit circumsporozoite protein Asn-Ala-Asn-Pro tetrapeptide repeat-pseudomonas toxin A, or hepatitis B vaccine. After quinine and doxcycycline, volunteers were followed for illness daily, parasitemia weekly, antibody, T-lymphocyte responses, and treated if indicated. Anopheles mosquitoes resting in houses were collected, and tested for P. falciparum antigen, or dissected for sporozoites and tested for blood meal ABO type and P. falciparum antigen. Vaccine was safe, with side-effects similar in both groups, and immunogenic, engendering IgG antibody as high as 600 micrograms ml-1, but did not increase the proportion of volunteers with T-lymphocyte responses. Estimation of P. falciparum challenge averaged 0.194 potentially infective Anopheles bites/volunteer/ day. Mosquito blood meals showed no difference in biting intensity between vaccine and control groups. Both groups had similar malaria-free survival curves, cumulative positive blood slides, cumulative parasites mm-3, and numbers of parasites mm-3 on first positive blood slide, during three post-vaccination observation periods. Every volunteer had P. falciparum parastemia at least once. Vaccinees had 82% and controls 89% incidences of symptomatic parasitemia (P = 0.514, efficacy 9%, statistical power 95% probability of efficacy < 50%). Vaccine-induced anti-sporozoite antibody was not protective in this study. Within designed statistical precisions the present study is in agreement with efficacy studies in Colombia, Venezuela and Tanzania.
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PMID:Plasmodium falciparum circumsporozoite vaccine immunogenicity and efficacy trial with natural challenge quantitation in an area of endemic human malaria of Kenya. 881 30

A new hepatitis B virus (HBV) mutant with an Asp to Ala substitution in aa144 of the envelope major protein was identified from the blood samples of two persistently infected patients. They were born to HBsAg-positive carrier mothers. The patients had been immunized with HBV vaccine after birth, under a standard schedule of 3 injections at 0, 1 and 6 months, but failed to be protected. The mutant was stable and was present in the blood samples collected at 1 and 4 years of age from patient 105. To study the antigenic differences, two expression plasmids, pExpW (wild type) and pExpM (mutant), were constructed, and HBsAgs were expressed in COS-M6 cells. The binding activities of the HBsAg from pExpW and pExpM were compared with anti-a-epitope monoclonal antibody and with anti-HBs polyclonal antibody, respectively, by radioimmunoassay. The results showed that the binding activity of HBsAg of pExpM was distinctly lower than that of pExpW, and the HBV mutant with envelope major protein144Asp-->Ala was shown to be a new immune escape variant.
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PMID:A new immune escape mutant of hepatitis B virus with an Asp to Ala substitution in aa144 of the envelope major protein. 883 56

During therapy of chronic viral hepatitis B (CVHB), some patients treated with natural human interferon alpha (nHuIFN-alpha) lozenges failed to respond. These observations triggered studies aimed to determine whether there are markers predicting patients' response to therapy with nHuIFN-alpha lozenges. In these studies, 32 patients with CVHB were involved: 20 males and 12 females, 16-61 years of age with proven persistent hepatitis B viremia (HBV). Patients were evaluated for clinical, biochemical liver function, and virological markers of disease. During 300 days of treatment of the patients received 75-150 IU nHuIFN-alpha daily in form of lozenges. The responders to oral interferon therapy were those who had initially alanine amino transferase (ALAT) level higher than 100 IU (85.7% cure rate) and weak responses were observed among patients who had an initial ALAT level below 100 IU (9.0% response rate). Therefore, ALAT test in patients with CVHB may serve as a predicting indicator of the outcome of IFN lozenges therapy.
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PMID:Natural human interferon alpha given orally has different effects on patients with distinct forms of chronic viral hepatitis B. 891 25

To investigate if the concomitant presence of hepatitis B virus (HBV) DNA and antibodies to hepatitis B surface antigen (anti-HBs) is associated with mutations in the HBV envelope gene, selected sequences of the HBV genome in 54 patients with chronic liver disease, collected from the Wuhan district of China, were amplified by polymerase chain reaction (PCR) and the DNA sequences of the products were determined. The part of the S gene coding for the 'a' determinant of HBsAg was found to be prone to diversity. A total of 19 aberations occurring at 11 of the 69 nucleotide positions of this part of the genome were found in sera from 15 HBsAg-negative but anti-HBs-positive patients. One of 13 HBsAg/HBeAg-positive and 8 of 17 HBsAg/anti-HBe-positive samples also showed point mutations in this gene sequence. Most prevalent was a point mutation from adenine to guanine at nucleotide 530 resulting in a change from threonine to alanine at amino acid position 126. This study highlights that the long time course of chronic HBV infection could favour a selection of escape mutants. The occurrence of such HBV variants in patients with chronic liver disease are not detected by conventional HBV serology, and the patients can therefore easily by be misdiagnosed. If viral mutants like those described here can be transmitted to other patients, there will be difficulties in identifying these infections, and conventional HBV vaccination will presumably not be protective against them.
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PMID:Increasing heterogeneity of the 'a' determinant of HBsAg found in the presumed late phase of chronic hepatitis B virus infection. 912 41

Fifty percent of healthy hepatitis B surface antigen carriers may have histologically proven chronic hepatitis. Our aim was to study the benefit of interferon-alpha in healthy patients. Twenty-nine hepatitis B surface antigen carriers with normal liver enzymes and with serum hepatitis B virus DNA were randomized into two groups: Group I, 14 patients treated with 9 megaunits of interferon alpha-2a thrice weekly for six months, and Group II, 15 control patients. A liver biopsy was obtained from each patient at study initiation. A second biopsy was available in nine treated patients and six controls. During treatment, a significant increase in alanine amino transferase levels was observed in treated patients as compared with the controls (P < 0.05). After treatment, transaminase levels decreased to normal values. No differences between treated and control patients were observed in clearance of hepatitis B virus markers. A significant increase in the total histological activity index between base line and final liver biopsies was observed in treated patients (P < 0.05). It is concluded that interferon alpha treatment may induce a biochemical and histological activation of liver disease. Accordingly, interferon alpha should not be administered to healthy hepatitis B surface antigen carriers, at least with the schedule used in this work.
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PMID:Activation of liver disease in healthy hepatitis B surface antigen carriers during interferon-alpha treatment. 929 36

Serum hepatitis B virus (HBV) DNA from 4 infants with fulminant hepatitis B, 3 infants with acute self-limited hepatitis B, and 15 infants with chronic HBV infection were amplified by polymerase chain reaction followed by direct sequencing of the region of HBV genome encoding the major antigenic epitopes of hepatitis B surface antigen (HBsAg). All infants were born to carrier mothers and administered immunoprophylaxis from birth. Serum HBV DNA from 13 carrier children born to carrier mothers who did not receive immunoprophylaxis and had comparable length of infection were studied as controls. An S mutant (residue 126, Thr to Ala) initially found in an infant with fulminant hepatitis was replaced by another S mutant (residue 145, Gly to Arg) 4 days later. In a girl with chronic hepatitis B, Ala-126 variant and Arg-145 variant were found at 17 and 25 months of age, respectively. The Arg-145 variant persisted for 8 years in an asymptomatic male carrier and for 1 year in an infant with chronic hepatitis B. The Ala-126 variant persisted for 11 years in one child who had an early loss of hepatitis B e antigen. In the majority of the infants' mothers, corresponding mutations in HBsAg were not detected in serum by direct sequencing. The S mutants detected in three carrier infants were not found in their mothers' serum after cloning and sequencing of 10 DNA clones from each maternal sample. None of the 13 control patients had detectable S mutants. These results suggest that S variants emerge or are selected under the immune pressure generated by the host or by administration of hepatitis B immune globulin and hepatitis B vaccination. An S mutant (residue 129, Gln to Arg) found in one mother-infant pair suggested a direct maternal-infant transmission, resulting in immunoprophylaxis failure. None of the family members of children infected with Arg-145 variant had the same variant infection, implying this variant's low transmissability.
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PMID:Surface gene mutants of hepatitis B virus in infants who develop acute or chronic infections despite immunoprophylaxis. 930 14

Envelopment of the hepatitis B virus (HBV) nucleocapsid depends on the large envelope protein L, which is expressed as a transmembrane polypeptide at the endoplasmic reticulum membrane. Previous studies demonstrated that the cytosolic exposure of the N-terminal pre-S domain (174 amino acids) of L was required for virion formation. N-terminal truncations of L up to Arg 103 were tolerated. To map sites in the remaining C-terminal part of pre-S important for virion morphogenesis, a series of 11 L mutants with linker substitutions between Asn 98 and Pro 171 was generated. The mutants formed stable proteins and were secreted in transfected cell cultures, probably as components of subviral hepatitis B surface antigen particles. All four constructs with mutations between Asn 98 and Thr 125 were unable to complement in trans the block in virion formation of an L-negative HBV genome in cotransfected HuH7 cells. These mutants had a transdominant negative effect on virus yield in cotransfections with the wild-type HBV genome. In contrast, all seven mutants with substitutions downstream of Ser 124 were able to envelop the nucleocapsid and to secrete HBV. The sequence between Arg 103 and Ser 124 is highly conserved among different HBV isolates and also between HBV and the woodchuck hepatitis virus. Point mutations in this region introducing alanine residues at conserved positions blocked virion formation, in contrast to mutations at nonconserved residues. These results demonstrate that the pre-S sequence between Arg 103 and Ser 124 has an important function in HBV morphogenesis.
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PMID:A short linear sequence in the pre-S domain of the large hepatitis B virus envelope protein required for virion formation. 937 94

Duck gp180 was previously identified by its ability to bind to the preS envelope protein of duck hepatitis B virus particles (Kuroki, K. , Cheung, R., Marion, P. L., and Ganem, D. (1994) J. Virol. 68, 2091-2096). Cloning and sequencing of gp180 cDNA revealed that it is a polyprotein with three carboxypeptidase-like domains (Kuroki, K., Eng, F., Ishikawa, T., Turck, C., Harada, F., and Ganem, D. (1995) J. Biol. Chem. 270, 15022-15028). To evaluate enzymatic properties of this protein, a soluble 170-kDa form of the protein (gp170) lacking the C-terminal transmembrane domain and cytoplasmic tail was expressed in a baculovirus system. The purified 170-kDa protein cleaved 5-dimethylaminonaphthalene-1-sulfonyl (dansyl)-Phe-Ala-Arg with a pH optimum of 5.5-6.5. With this substrate at pH 5.5, the 170-kDa protein displayed a Km of 12 microM and a Kcat of 57 s-1. Dansyl-Pro-Ala-Arg and dansyl-Phe-Phe-Arg were cleaved with Km values of 17 and 21 microM, and Kcat values of 57 and 17 s-1, respectively. Constructs containing only the first or second carboxypeptidase domains also showed enzymatic activity. The effects of inhibitors and ions on enzyme activity of gp170 were generally similar to the effects of these compounds on purified bovine carboxypeptidase D. To evaluate the regions within gp180 necessary for binding preS, a series of deletion mutants were expressed in the 293T human kidney cell line. Deletions of the first and second domains, leaving the third domain intact, eliminated carboxypeptidase activity but retained preS binding. Deletion of the third domain eliminated preS binding but not carboxypeptidase activity. These results indicate that the third domain is responsible for preS binding, and this binding does not require carboxypeptidase activity.
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PMID:gp180, a protein that binds duck hepatitis B virus particles, has metallocarboxypeptidase D-like enzymatic activity. 952 48


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