HBV Mutants Research Articles

Detection of precore hepatitis B virus mutants in asymptomatic HBsAg-positive family members

Precore hepatitis B virus mutants have been detected mainly in HBeAg-negative patients with active liver disease. We previously reported two novel mutations: M1 (C-to-T change at nucleotide 1856 [proser at codon 15]) and M3 (G-to-A change at nucleotide 1898 [gly-ser at codon 29]) in addition to two well-described mutations: M2 (G-to-A change at nucleotide 1896 [trp-stop at codon 28]); and M4 (G-to-A change at nucleotide 1899 [gly-asp at codon 29]) in Chinese patients. The aims of this study were to determine (a) the prevalence of precore HBV mutations in asymptomatic carriers and (b) whether family members share the same mutated sequence as the index patients. Fifty-three index patients and 89 HBsAg-positive family members were studied by means of direct sequencing of polymerase chain reaction-amplified hepatitis B virus DNA. M0, a conserved mutation (T-to-C at nucleotide 1858, codon 15), was detected in 81% and 12% family members of index patients with and without M0, respectively (p < 0.0001). The clustering of M0 indicates that most subjects were infected through intrafamilial transmission. M1 was detected in all the family members of patients with M1 but in none of the family members of patients with wild-type or M2 sequences (p < 0.0001). M2 was detected in 25%, 0% and 15% of family members of patients with M2, M1 and WT sequences, respectively (p = 0.19). M3 was detected in five and M4 in four family members.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular immunity and HBV persistence in patients with and without HBV mutants

Cellular immunity and HBV persistence in patients with and without HBV mutants

第22回日本総合健診医学会学術大会講演抄録集 HBe抗原セロコンバージョン血清でのHBV (変異株) の存在 (PCR (MSSA) 法を用いて)

第22回日本総合健診医学会学術大会講演抄録集 HBe抗原セロコンバージョン血清でのHBV (変異株) の存在 (PCR (MSSA) 法を用いて)

Replication defective HBV mutant from an immunologically negative patient

Replication defective HBV mutant from an immunologically negative patient

Antigenic analysis by monoclonal antibodies of HBsAg transcribed from a vaccine escape HBV mutant in cell culture

Antigenic analysis by monoclonal antibodies of HBsAg transcribed from a vaccine escape HBV mutant in cell culture

Predictive value of pre-core HBV mutants in spontaneous & interferon induced HBeAg clearance . Tulane Univ & VA Medical Center, New Orleans, LA

Predictive value of pre-core HBV mutants in spontaneous & interferon induced HBeAg clearance . Tulane Univ & VA Medical Center, New Orleans, LA

Detection of pre-core HBV mutations in asymptomatic HBsAg+ family members . Tulane Univ and VAMC, New Orleans, LA

Detection of pre-core HBV mutations in asymptomatic HBsAg+ family members . Tulane Univ and VAMC, New Orleans, LA

Cytotoxic T lymphocyte activity and HB virus mutant in chronic HB virus carriers.

We conclude that firstly, in our system it appears that HBV Ag-specific CTL response is mediated by CD8-positive T cells with HLA class I restriction, and in chronic HBV carriers, CTL response is mainly directed towards nucleocapsid antigen. Secondly, mutant HBV in pre-core and core region is deeply related to the clinical course of the disease. Some variants should be targeted for the CTL response. Altenatively, others may escape the immunosurveillance of CTL by altering the relevant T-cell epitope. However, further study will be necessary to confirm how CTL response changes and what clones are cleared or escape by aggravation of the illness.

Nucleotide sequence of a cloned human HBV mutant (pDKHBV) in duck hepatoma of Qidong County.

This is the first report to describe the presence of an HBV-like DNA sequence in two hepatoma and their tumor surrounding liver tissues, one precancerous and one non-malignant liver tissue of ducks collected from Qidong County of China. The HBV-like sequences were either in an episomal form of 3.2 kb or in an integrated form of various sizes, while the DHBV DNA sequences (3.0 kb) were either present or absent in these tissues and in different size pattern. Furthermore, there was no evidence of cross-hybridization between HBV-like DNA sequences in duck and DHBV DNA. A 3.2 kb HBV-like DNA sequence has been cloned from one duck hepatoma (40 K), designated as pDKHBV. The 3218 bp full-length nucleotide sequence of this clone has been determined, which had no apparent homology with Duck Hepatitis B Virus (DHBV) genome, but was highly homologous to human HBV adw2 subtype (99.0%). The sequence was composed of four open reading frames for HBV gene Pre-S/S, X, C and P respectively. In addition to multiple sites of point mutation, one nt and two nt deletion were detected downstream the initiation codon of Pre-S1 gene and at the 3' end of C gene respectively, thereby suggesting a frameshift mutation in Pre-S gene and C gene. Based on these results, it was implicated that an unusual HBV variant might exist in Qidong County, which might have transmitted into duck through some yet unknown mechanisms. The possibility from exogenous contamination could be thus excluded.

Detection of the hepatitis B virus major pre-core mutation by the amplification refractory mutation system technique

HBeAg/anti-HBe seroconversion is associated, in some patients affected by type B chronic active hepatitis (CAH), with the occurrence of HBV pre-core mutants characterized by a common G-A change at codon 83. Since this mutation has important clinical correlations, we tried to develop a fast and reliable PCR test based on the amplification refractory mutation system (ARMS) technique, which has been successfully used to identify point mutations associated with genetic diseases. Following this approached, we analysed HBV particles isolated from 7 patients with anti-HBe CAH and previously characterized by DNA sequencing. Sera containing only wild type or mutant HBV DNA or a combination of both showed a discrete amplification product only in the presence of the specific wild type or mutant upstream primer. These results confirm the efficacy of the ARMS technique in detecting in a rapid and specific fashion the most common and clinically relevant HBV pre-core mutation.

Absence of hepatitis B virus precore mutants in patients with chronic hepatitis B responding to interferon-alpha.

Precore defective HBV mutants may gradually prevail because of immune selection and explain spontaneous seroconversion from HBeAg to anti-HBe in HBV carriers. We have analyzed whether the presence of precore HBV mutants is a determinant of responsiveness to interferon-alpha therapy. Fifteen carriers (nine responders and six nonresponders) who were treated with interferon-alpha were examined. Serum samples were collected before and after therapy. After extraction of DNA, the precore region was amplified by the polymerase chain reaction, and the product was identified by gel electrophoresis and ethidium bromide staining and then Southern blotting and molecular hybridization. The amplified products in all patients were asymmetrically amplified by a modified polymerase chain reaction, and the precore region was directly sequenced. All patients were HBV DNA positive initially. Circulating HBeAg-negative mutants were not identified before treatment in either responders or nonresponders. All nine responders were negative for HBV DNA in serum by dot blot during or after treatment, but seven remained positive by polymerase chain amplification and Southern-blot hybridization. All of the nonresponders remained positive for HBV DNA by dot blot. A silent mutation involving the substitution of an A for G at position 1888 was found in seven carriers; however, no HBeAg-negative mutants were detected in the follow-up of either responders or nonresponders to interferon-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Pre-core HBV mutants: Response to interferon therapy

Pre-core HBV mutants: Response to interferon therapy

HBe antibody unrelated to ‘e minus’ hepatitis B virus variant infection in patients with chronic type D hepatitis

The presence of HBV-DNA sequences was evaluated in DNA extracted from serum samples, peripheral blood lymphocytes and liver biopsy specimens of five HBsAg/anti-HBe-positive carriers with chronic HDV infection. DNAs were tested by polymerase chain reaction (PCR) amplification technique using two pairs of oligonucleotide primers specific for the preC/C and S regions of the HBV; viral sequences were found exclusively in liver extracts and only in three out of the five cases. The direct sequencing of the amplified preC/C regions showed wild-type sequences in two cases, while in the third case a combination of 'wild' and 'e minus variant' viral populations was observed. Moreover, liver DNA of one positive case was electrophoresed through a low melting agarose gel and the following amplification, performed on DNA re-extracted from three different fragments of the gel, showed the presence of free HBV genomes but the absence of replicative intermediate forms. These results show that anti-HBe positivity is not constantly related to precore mutant HBV infection and suggest that HDV inhibits HBeAg production. Moreover, as it was observed in 'e minus' HBV variants, also during a chronic HBV wild-type infection, the viral replication might be suppressed to undetectable levels.

Replicating and virion secreting hepatitis B mutant virus unable to produce preS2 protein

Mutant HBV genomes unable to produce preS2 protein were identified in the serum of a highly viremic chronic carrier. By direct sequencing of the amplified preS region and by sequencing of 50 cloned amplified preS DNA fragments all molecules were found to have deleted the preS2 translation initiation codon and three amino acids 54 nucleotides downstream thereof. In addition, numerous amino acid changes, predominantly located between both deletions, were revealed. HBV-DNA genomes containing the mutated preS sequences were shown to be replication competent and to secrete efficiently virions that were morphologically and by the type of DNA encapsidated not distinguishable from wild-type virus. These data demonstrate that HBV with mutated preS sequences and unable to express preS2 protein can occur as a dominant or exclusive virus population in a highly viremic chronic carrier. The data also show that expression of the preS2 protein is not essential for HBV replication, virion morphogenesis and secretion.

Complementation analysis of mutants defective in different steps of HBV reverse transcription

The HBV P gene encodes a multifunctional polyprotein which contains the major enzymatic activities required for hepadnaviral reverse transcription (protein primer, DNA polymerase, and RNase H). Mutant HBV genomes unable to synthesize fully functional P gene products were analysed for their potential to be rescued by a second mutant HBV genome that either contained a wild type P gene (intergenic complementation) or a mutation in a functionally different P gene domain (intragenic complementation). This analysis was carried out by cotransfecting two mutants at a time into HepG2 cells and assaying for the production of core particles containing DNA polymerase activity. The results obtained demonstrate the existence of intergenic, but not of intragenic complementation. This indicates that the primary P gene product is not processed before core assembly, and furthermore that there is a rather free mixing of all HBV gene products in the HBV infected cell which can lead to the efficient propagation of defective viral genomes.