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Wild-type HBV (wild-type + hbv)
Selected AbstractsSpontaneous HBeAg seroconversion and loss of hepatitis B virus DNA after acute flare due to development of drug resistant mutants during entecavir monotherapyHEPATOLOGY RESEARCH, Issue 1 2009Ri-Cheng Mao Aims:, Patients with chronic hepatitis B virus (HBV) infection under entecavir (ETV) treatment develop resistant mutants with viral rebound. Here, we report an interesting case of spontaneous loss of HBV-DNA and seroconversion following an acute flare after the development of ETV-resistant mutants. This patient received ETV after lamivudine breakthrough. Methods:, Cloning and sequence analysis of the HBV reverse transcriptase (RT) region were performed with seven samples during ETV therapy. In addition, two full-length HBV genomes derived from samples before and after the emergence of ETV resistance were sequenced. Results:, ETV resistant mutants appeared at week 228, with virological and biochemical rebound at the same time. Unexpectedly, HBeAg seroconversion occurred 8 weeks later. The viral load decreased and became undetectable from week 252. Analysis of HBV isolates in the patient at week 124 revealed that wild-type HBV was predominant at that time and ETV resistant mutants were not found among 20 clones. Interestingly, a new mutant type with rtL180M+rtT184L was found alongside rtL180M+rtT184L+rtM204V/I at week 228 and appeared to develop independently, according to the sequence analysis. In contrast to the previously identified ETV resistant mutants, it did not carry the rtM204V/I mutations. Conclusion:, The data presented here indicates that the flare following the emergence of ETV resistant mutants may reflect immune-mediated control of HBV infection, leading to a spontaneous loss of HBV-DNA and seroconversion. [source] TLRs antiviral effect on hepatitis B virus in HepG2 cellsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2008C. Xia Abstract Aims:, A hepatoma cell line, HepG2, was used as a model system to detect Toll-like receptor (TLR) expression in hepatocytes and examine the antiviral effect on hepatitis B virus (HBV). Methods and Results:, Toll-like receptor expression was detected in HepG2 cells by RT-PCR. The TLRs, which were strongly expressed in HepG2 cells, were stimulated with specific ligands. Interferon (IFN) response was evaluated poststimulation with Western blotting for signal transduction and activators of transcription-1. Furthermore, HepG2 cells were transiently transfected with wild-type HBV 1·3-fold over-length plasmid and treated with specific ligands at indicated times. Replication of HBV DNA, transcription of HBV RNA intermediate and expression of HBV antigens were respectively detected by Southern blotting, real time PCR, ELISA and Western blotting. Activation of different TLRs induced antiviral effects on HBV to varying degrees. Conclusions:, The TLRs, which were strongly expressed in HepG2 cells, could be stimulated with specific ligands. Activation of TLRs induced apparent production of antiviral cytokines such as IFN-,/, and inhibited HBV lifecycle in the hepatocyte cell model. Significance and Impact of the Study:, Expression of TLRs in hepatocytes may be related to local immunity of liver and participate in the outcome of viral hepatitis. [source] Molecular characterization of a variant virus that caused de novo hepatitis B without elevation of hepatitis B surface antigen after chemotherapy with rituximabJOURNAL OF MEDICAL VIROLOGY, Issue 12 2008Masami Miyagawa Abstract Hepatitis B virus (HBV) reactivation in hepatitis B surface antigen (HBsAg)-negative patients following treatment with rituximab has been reported increasingly. The aim of this study was to investigate the molecular mechanisms underlying HBV reactivation in an HBsAg-negative patient. HBV was reactivated in a 75-year-old man following chemotherapy with rituximab, without elevation of HBsAg. The patient's full-length HBV genome was cloned and the entire sequence was determined. Transfection studies were performed in vitro using recombinant wild-type HBV (wild-type), the patient's HBV (patient), and two chimeric HBV constructs, in which the preS/S region of the patient and wild-type virus had been exchanged with one another. Secreted HBsAg and intra- and extra-cellular HBV DNA were measured. The number of amino acid substitutions in HBV from this patient was much higher than in previous reports of HBV mutants, such as occult HBV and vaccine escape HBV mutants. Levels of HBsAg and HBV DNA production in vitro were significantly lower in the patient compared to wild-type transfections. From analyses of the chimeric constructs, the altered preS/S region was responsible mainly for this impairment. These results show that highly mutated HBV can reactivate after chemotherapy with rituximab, despite an unusually large number of mutations, resulting in impaired viral replication in vitro. Severe immune suppression, probably caused by rituximab, may permit reactivation of highly mutated HBV. These findings have important clinical implications for the prevention and management of HBV reactivation and may explain partially the mechanism of recent, unusual cases of HBV reactivation. J. Med. Virol. 80:2069,2078, 2008. © 2008 Wiley-Liss, Inc. [source] Dynamics of lamivudine-resistant hepatitis B virus during adefovir monotherapy versus lamivudine plus adefovir combination therapyJOURNAL OF MEDICAL VIROLOGY, Issue 7 2008Samreen Ijaz Abstract Adefovir dipivoxil has been used alone or together with lamivudine to suppress lamivudine-resistant hepatitis B virus (HBV). However, the dynamics of HBV populations under different selection pressures and their impact on treatment outcome are poorly understood. Pyrosequencing® was applied to quantify longitudinally the evolution of wild type and lamivudine/ adefovir-resistant HBV. Eight patients, with lamivudine-resistant HBV, were randomized to receive adefovir monotherapy or adefovir/lamivudine combination therapy for a median of 79 and 71 weeks, respectively. Pyrosequencing® proved highly sensitive with a lower limit of quantitation of minor HBV populations of 2% irrespective of viraemia levels. Adefovir/lamivudine treatment resulted in greater viraemia reduction than adefovir monotherapy. During combination therapy, lamivudine-resistant HBV populations (codons 180 and 204) remained dominant (>90%) and no adefovir-resistance developed. During adefovir monotherapy, reversion to wild-type HBV was detected in two patients with one patient accumulating rapidly adefovir-resistant HBV along with increased viraemia. In conclusion, the dynamics of drug-resistant HBV strains vary under different selection pressures which have a significant impact on the success of rescue therapy, as well as for the selection of new mutations. The use of techniques such as Pyrosequencing provides an evidence-based approach for successful management of drug-resistant HBV. J. Med. Virol. 80: 1160,1170, 2008. © 2008 Wiley-Liss, Inc. [source] Role of surface promoter mutations in hepatitis B surface antigen production and secretion in occult hepatitis B virus infection,JOURNAL OF MEDICAL VIROLOGY, Issue 3 2007Sonali Sengupta Abstract The production, secretion, and localization of surface proteins of hepatitis B virus (HBV) and the ratio of large to small surface protein S was studied in HepG2 cells transfected with the wild-type and mutant pre-S1 and pre-S2/S promoters of HBV molecular clones 313.1 (GenBank accession no. AY161147) and 761.1 (GenBank accession no. AY161159) from two patients with occult HBV infection. Fusion constructs were made by in frame fusion of the wild-type surface gene to the mutant pre-S1 and pre-S2/S promoters and wild-type promoter so that the structural part of the small surface protein remains identical. HepG2 cells transfected transiently were used for analysis. HBV surface proteins production and secretion was determined by enzyme linked immuno assay (ELISA) and localization by immunofluorescence. Immunoprecipitation of the large, middle, and small surface protein was carried out in transient transfected and metabolically labeled cells to determine the ratio of the large to small surface protein. The results indicate that HepG2 cells transfected with mutant HBV promoters had reduced HBV surface proteins secretion compared to wild-type HBV. HepG2 cells transfected with mutant HBV pre-S1 and pre-S2/S promoters showed cytoplasmic aggregation of HBV surface proteins compared to wild-type HBV promoters, which showed diffuse cytoplasmic localization. In all cases, the HBV surface proteins localized to the endoplasmic reticulum. The ratio between the large and small surface protein was 1.89 and 0.56 with mutant HBV 313.1 and 761.1 pre-S1 and pre-S2/S promoters, respectively, compared to 0.17 in wild-type. Thus, the aggregation of surface proteins, altered ratio and secretion of surface proteins were possibly the causes of occult hepatitis B infection. J. Med. Virol. 79:220,228, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||