Search results for "EPAD"

Hepatitis B virus with antigenically altered hepatitis B surface antigen is selected by high-dose hepatitis B immune globulin after liver transplanta…

1998

“Escape” variants of hepatitis B virus (HBV) can cause infection despite previous immunization. These viruses show alterations of the immunogenic major hydrophilic loop of the HBV small surface protein (s-protein). We studied whether HBV “escape” variants were selected in patients with graft infection after liver transplantation for HBV-related diseases who received passive immunoprophylaxis with high-dose polyclonal hepatitis B hyperimmune globulin (HBIG). For that, pre- and posttransplantation sera of 34 patients were analyzed for the occurence of HBV S-gene variants. In addition, binding of in vitro–translated variant s-proteins to HBIG was studied. Variants with exchanges of amino acid …

Mutation specific PCR and direct solid phase sequencing assay for the detection of hepatitis B virus pre-C/C mutants in anti-HBe-positive, chronic he…

1994

Sequence analysis of the HBV DNA from patients with anti-HBe+, chronic hepatitis B revealed that the lack of HBeAg is mostly due to a single GA transition at nucleotide position 1896, resulting in a translational stop codon. A point mutation-specific polymerase chain reaction (msPCR) for the detection of this genetic variant was established. Two serologically defined groups of patients with symptomatic chronic hepatitis B (HBeAg+ n = 14, anti-HBe+ n = 11) were included in this study. Viral DNA from 43 sera (26 eAg+/17 anti-HBe+) was amplified twice, using two different sets of PCR primers. Each set contained the same — strand primer, but the + strand primers differed at their 3′-end, thus b…

The significance of the pre-S region of the hepatitis B virus

1986

Biological standards for hepatitis B virus assays.

1992

Semiquantitative assessment of pre-core stop-codon mutant and wildtype hepatitis B virus during the course of chronic hepatitis B using a new PCR-bas…

1996

In most patients with chronic hepatitis B positive for antibodies (anti-HBe) to HBe antigen (HBeAg), a pre-core mutant hepatitis B virus (HBV) with a point-mutation at nt. 1896 can be isolated. Clinical significance of the mutant virus in chronic hepatitis B is not proven yet, and screening of large numbers of sera during different clinical courses of numerous patients is necessary. We therefore aimed to develop a fast and reliable assay, that allows to discriminate wildtype from nt. 1896 G-->A mutant HBV and to determine the ratio of mutant and wildtype HBV in patients' sera. A mutation specific polymerase chain reaction (ms PCR) with new primers served to distinguish nt. 1896 G-->A mutant…

Pre-core mutants of hepatitis B virus in patients receiving immunosuppressive treatment after orthotopic liver transplantation.

1996

Orthotopic liver transplantation (OLT) is a possible treatment for acute or chronic liver failure due to hepatitis B virus (HBV) infection, but reinfection of the graft can be a serious complication. The aim of this study was to monitor HBV markers, to analyse pre-core-/core-mutations as well as to identify the viral population causing reinfection after OLT, and to investigate the emergence or disappearance of these mutants in patients receiving immunosuppressive treatment. Fifty-four pre-and posttransplant serum samples of 17 patients were analysed. All patients underwent OLT for HBV-related liver disease and had HBV-DNA before and after OLT. Total DNA was extracted from all sera and a 240…

Selection of hepatitis B virus variants with aminoacid substitutions inside the core antigen during interferon-? therapy

2000

The hepatitis B virus (HBV) core antigen carries many epitopes relevant for B and T cell response that show aminoacid variation during viral infection. In a longitudinal analysis, sequential serum samples of 15 patients that suffered from chronic HBV infection were collected before, during, and after high-dose IFN-α treatment. The HBV preCore/Core (preC/C) sequence of the selected samples in each patient was determined and analysed for sequence variations compared to the pretreatment sample. The positions of HBV core aminoacid substitutions were assigned to immunodominant B, CD4+ and CD8+ cell epitopes. Seventy-five percent of all aminoacid substitutions were found within immunodominant T a…

Myristylation is involved in intracellular retention of hepatitis B virus envelope proteins

1991

The envelope of hepatitis B virus contains three related proteins, one of which is myristylated. The nonmyristylated small and middle protein are assembled into empty envelope particles which are secreted from cells, whereas the myristylated large envelope protein is mainly found in complete virions and is not secreted in the absence of the nucleocapsid. The block to secretion can be partially overcome by mutation or deletion of the myristylation site. Creation of a myristyl attachment site in the small protein impairs the secretion of empty envelope particles but not their intracellular assembly. Myristylation may therefore play a crucial role in hepatitis B virus replication by channeling…

Modification of Hepatitis B Virus Infection by Recombinant Leukocyte Alpha A Interferon

1986

A defect in alpha interferon production in patients with chronic type B hepatitis offers a rationale principle for treating this disease with interferon. Two trials with interferon in chronic type B hepatitis indicate that this therapy achieves an elimination of HBsAg and HBeAg significantly higher than spontaneous. Our study and that of others indicate, however, that the response to interferon therapy is dependent on many variables including: the type of interferon, the interferon dose, duration of interferon treatment, sex, sexual preference in men and coinfection with other viruses. As of the multiple modes of action of interferon, a better understanding of viral replication, of the anti…

Functional analysis of a rare HBV deletion mutant in chronically infected children.

2003

Liver damage caused by chronic hepatitis B virus (HBV) infection may be enhanced through the selection of deleted HBV preS mutants by intracellular accumulation of viral proteins and subsequent cell death. However, the prevalence and impact of such mutants on the clinical course of infection have not yet been studied in children. Serum samples from 60 children (mean age 9.8 y) were investigated by means of PCR and direct sequencing of the entire preS region. Only one patient (1.5%) was found with a mixed HBV population of a deletion spanning 183 nucleotides and wild-type sequences. This mutation alters the HBV large-surface protein and removes the small-surface promoter. To clarify the sign…