Search results for "hepadnaviridae"
showing 10 items of 57 documents
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…
Detection of different viral strains of hepatitis B virus in chronically infected children after seroconversion from HBsAg to anti-HBs indicating vir…
1998
Abstract Background/Aims: Seroconversion to anti-HBs or the loss of HBsAg is usually associated with complete elimination of the replicative hepatitis B virus. Usually in these patients hepatitis B virus DNA (HBV DNA) becomes undetectable. Routine controls of patients who underwent anti-HBs seroconversion by more sensitive tests showed that in some cases the virus persisted in the patient. Therefore the aim of our study was to evaluate if virus persistence could also be found in children with chronic hepatitis B after anti-HBs seroconversion. The virus pool should be characterized before and after seroconversion. Methods: Viral DNA was extracted from nine HBsAg negative or anti-HBs positive…
HBV viral load within subpopulations of peripheral blood mononuclear cells in HBV infection using limiting dilution PCR.
1999
Abstract Extrahepatic viral load in peripheral blood mononuclear cells (PBMCs) of patients with hepatitis B virus (HBV) is still under debate. In this study, HBV infection rates and viral titers were examined within all PBMC subpopulations using limiting dilution-PCR (LD-PCR). PBMCs of patients with acute or chronic hepatitis B were separated by magnetic beads in monocytes, B-cells, CD4+ T-cells, CD8+ T-cells, and NK cells. Using two-round nested PCR, HBV-DNA sequences were detected in all patients examined within each PBMC subpopulation. The frequencies of HBV-positive cells and viral loads were calculated by Poisson analysis of HBV PCR results from serial dilutions of cells and cell lysat…
A review of virus infections of cataceans and the potential impact of morbilliviruses, poxviruses and papillomaviruses on host population dynamics.
1999
Viruses belonging to 9 families have been detected in cetaceans. We critically review the clinical features, pathology and epidemiology of the diseases they cause. Cetacean morbillivirus (family Paramyxoviridae) induces a serious disease with a high mortality rate and persists in several populations. It may have long-term effects on the dynamics of cetacean populations either as enzootic infection or recurrent epizootics. The latter presumably have the more profound impact due to removal of sexually mature individuals. Members of the family Poxviridae infect several species of odontocetes, resulting in ring and tattoo skin lesions. Although poxviruses apparently do not induce a high mortali…
Hepatocytes of double-transgenic mice expressing high levels of hepatitis B virus e antigen and interferon-gamma are not injured by HBeAg specific au…
2000
Seroconversion from HBeAg to alphaHBe of persons chronically infected by HBV is usually associated with a transient exacerbation of liver disease and subsequent normalization of liver histology. It is speculated that these clinico-pathological features may be due to the activation of cytodestructive mechanisms by alphaHBe antibodies. The aim of the present study was to investigate the pathogenic potential of alphaHBe antibodies in a transgenic mouse model. Therefore, alphaHBe autoantibodies were elicited in double-transgenic mice expressing high amounts of HBeAg and interferon-gamma in the liver. Interferon-gamma has reviously been shown to play an important role in the development of hepat…