Effects of a naturally occurring mutation in the hepatitis B virus basal core promoter on precore gene expression and viral replication

Molecular and serological characterization of hepatitis B virus genotype A and D infected blood donors in Poland

Hepatitis B virus (HBV) genotypes have distinct geographical distributions and influence severity of clinical outcome and response to antiviral therapies. HBV polymorphism in HBV surface antigen (HBsAg) positive first time blood donors from Poland was examined. HBV serological markers and HBV DNA were tested in 170 samples. Whole genome (n = 53) or specific region sequences: pre-S/S and basic core promoter/precore (BCP/PC) region (91 and 154 samples, respectively) were phylogenetically analyzed. The median age of infected donors was 21 years. Anti-HBs, anti-HBe and hepatitis B e antigen were detected in 5%, 92.4% and 10.5% of tested donors, respectively. The HBV DNA load ranged between unquantifiable and 3.1 x 10(10) IU/mL (median: 4.10 x 10(3) IU/mL). Genotypes A2 (81.2%) and D (18.8%) co-circulated. Phylogenetic analyses revealed differences between the genotypes. Viral load and level of HBsAg tended to be lower in genotype D. The median HBsAg/HBV DNA ratio expressed in IU/mL was one for both genotypes, but very low or very high ratios appeared more frequent in genotype D infections. Higher amino acid variability in the surface proteins (median: 4%vs 1.5%; P = 0.01) and in the major hydrophilic region was observed in genotype D (P = 0.01). BCP/PC region analysis revealed the double mutation 1762T/1764A in 49/125 (39.2%) genotype A2 and 6/29 (20.7%) genotype D strains (P = 0.08). Mutations in PC and BCP regions correlated neither with HBsAg nor HBV DNA levels. HBV genotype A2 is dominant in HBsAg positive donors in Poland. Minority genotype D strains are significantly more substituted than genotype A2 strains potentially affecting the course of infection.

Hepatocellular carcinoma in the world and the middle East

Hepatocellular carcinoma (HCC) is a major worldwide public health concern. Despite recent advances, there has been little success in improving the survival of HCC patients. Due to advances in diagnostic modalities and the increasing incidence of chronic viral hepatitis and nonalcoholic fatty liver disease (NAFLD), both of which are well known risk factors of HCC, the prevalence of HCC is increasing in developed countries and it is expected that this trend will continue in the future. In Middle Eastern countries the prevalence of this cancer is lower compared to sub-Saharan Africa and some Far East countries; however it is documented that the prevalence of this cancer in some parts of the Middle East is also increasing. In the current review, the prevalence and burden of this disease worldwide, particularly in Middle Eastern countries, and risk factors for HCC are discussed.

Enhanced intracellular retention of a hepatitis B virus strain associated with fulminant hepatitis

A plasmid carrying 1.3-fold HBV genome was constructed from a HBV strain that caused five consecutive cases of fulminant hepatitis (pBFH2), and HepG2 cells were transfected with pBFH2 or its variants. The pBFH2 construct with A1762T/G1764A, G1862T, and G1896A showed the largest amount of core particle-associated intracellular HBV DNA, but no significant increase of extracellular HBV DNA in comparison with the wild construct, suggesting that these mutations might work together for retention of the replicative intermediates in the cells. The retention might relate to the localization of hepatitis B core antigen (HBcAg) in the nucleus of HepG2, which was observed by confocal fluorescence microscopy. HBcAg immunohistochemical examination of liver tissue samples obtained from the consecutive fulminant hepatitis patients showed stronger staining in the nucleus than acute hepatitis patients. In conclusion, the fulminant HBV strain caused retention of the core particles and the core particle-associated HBV DNA in the cells.

Risk factors for early and late recurrence in hepatitis B-related hepatocellular carcinoma

BACKGROUND/AIMS

Hepatitis B virus (HBV) levels correlate with the development of hepatocellular carcinoma (HCC), but the role of viral load in HCC recurrence after tumor resection remains unclear. Herein we aimed to investigate the role of viral load in HCC recurrence following tumor resection.

METHODS

From 1990 to 2002, 193 HBV-related HCC patients who underwent tumor resection in Taipei Veterans General Hospital were enrolled. Serum HBV DNA level and mutations were analyzed for association with early and late recurrence, together with other clinical variables.

RESULTS

During a follow-up of 58.2+/-44 months, 134 patients had HCC recurrence. Multivariate analysis showed that multinodularity (Hazard ratio [HR], 95% confidence interval [CI]; 2.232, 1.021-4.878), macroscopic venous invasion (4.693, 1.645-13.391), AFP >20 ng/ml (3.891, 1.795-8.475), and cut margin <or= 1cm (3.333, 1.487-7.470) were correlated with early recurrence (within two years of operation) of HCC. In addition, multivariate analysis determined that Ishak hepatic inflammatory activity >6 (4.658, 1.970-11.017), multinodularity (3.266, 1.417-7.526), ICG-15 >10% (2.487, 1.095-5.650) and HBV DNA level >10(6) copies/ml (2.548, 1.040-6.240) were significantly associated with late recurrence (>two years after resection). Patients with high viral loads tended to have higher Ishak inflammatory (7.00+/-3.07 vs. 5.33+/-2.96, p=0.001) and fibrosis scores (4.17+/-2.01 vs. 3.20+/-2.41, p=0.007) than those with lower loads.

CONCLUSIONS

Tumor factors were associated with early HCC recurrence while high viral loads and hepatic inflammatory activity were associated with late recurrence. Pre- and post-operative antiviral and anti-inflammatory therapies may be crucial in reducing late recurrence.

Lamivudine treatment in a patient with hepatitis B virus reactivation after allogenic peripheral bone marrow transplantation

We report the case of a 52-year-old woman with hepatitis B virus (HBV) reactivation during treatment for chronic graft vs. host disease (GVHD) after peripheral bone marrow transplantation (PBSCT) to treat chronic myelocytic leukemia. She was given cyclosporine and prednisolone orally to treat chronic GVHD after PBSCT. Liver dysfunction first developed 25 months after transplantation with the appearance of hepatitis B s antigen (HBsAg), hepatitis B e antigen (HBeAg), and elevation of HBV-DNA up to 4.5 log copies/ml. Retrospective examination of her serum before PBSCT proved negative for HBsAg and HBeAg, and positive for anti-HBsAg, anti-HBeAg, anti-hepatitis B core antigen, and HBV-DNA (2.7 log copies/ml), showing that she was in a state of occult HBV infection. Nucleotide sequences of the HBV genome obtained from her serum showed no core promoter mutations at nt 1762 and 1764 and no pre-core mutation at nt 1896. Polymerase chain reaction-restriction fragment length polymorphism showed that she was infected with HBV genotype B. The administration of lamivudine, a nucleoside analog, improved her liver function and reduced HBV-DNA replication. We conclude that antiviral agents, such as lamivudine, are effective for treating hepatitis B reactivation during immunosuppressive treatment, such as for GVHD. The administration of a nucleoside analog before transplantation should also be considered in the light of HBV genotypes and mutations, even if HBsAg was negative and the viral load was low before transplantation.

Hepatitis B virus variants

HBV replicates through reverse transcription of an RNA intermediate; the inherent lack of proofreading causes a high mutation frequency. Mutations in the precore and core promoter regions that abolish or reduce the production of hepatitis B e antigen occur most commonly. Patients with these HBV variants remain viremic and can develop progressive liver disease. Mutations in the core promoter region are associated with an increased risk of hepatocellular carcinoma. Exogenous selection pressure might favor certain mutations. Mutations in the HBV polymerase that confer resistance to nucleoside and nucleotide analog treatments are a major barrier to the success of therapy for hepatitis B. The development of antiviral drug resistance negates the initial treatment response and can lead to hepatitis flares and hepatic decompensation. Prompt addition of another drug to which the virus is not cross-resistant is required. Mutations in the HBV surface protein that facilitate escape from host immunity are responsible for the failure of immune prophylaxis in infants who received HBV vaccine and in liver transplant recipients who received hepatitis B immune globulin.

To "be" or not to "be": that is the question

Treatment guidelines currently consider hepatitis B early antigen (HBeAg) seroconversion to be the end point of treatment with oral antivirals for HBeAg-positive patients. However, it is clear that with the high HBeAg relapse rate (both natural and after treatment) along with the high rate of mixed infection and the prevalence of HBeAg-negative disease, HBeAg status can no longer be considered the most useful end point of treatment or the signal to initiate therapy. Hepatitis B surface antigen (HBsAg) loss or seroconversion is associated with a favorable prognosis in both HBeAg-positive and HBeAg-negative disease and should be considered the test result that, combined with undetectable HBV DNA, will trigger treatment cessation.

The correlation of hepatocyte nuclear factor 4 alpha and 3 beta with hepatitis B virus replication in the liver of chronic hepatitis B patients

Hepatocyte nuclear factors 4 alpha (HNF4alpha) and 3 beta (HNF3beta) are members of a group of liver-enriched transcription factors (LETFs) that play important roles in regulating the replication of hepatitis B virus (HBV). Using cell culture and animal models, we showed that HNF4alpha supports HBV replication in nonhepatic cells and HNF3beta inhibits HBV replication. However, the expression of HNF4alpha and HNF3beta in the liver tissue of chronic HBV-infected patients and the relationship between the levels of HNF4alpha and HNF3beta and HBV replication are unclear. In this study, liver biopsy specimens from 86 chronic HBV-infected patients were collected. The expression levels of HNF4alpha, HNF3beta, hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) were detected by an immunohistochemical technique and the level of HBV DNA was checked by in situ hybridization with serial sections from liver biopsy tissue samples. We show here that samples with higher levels of HNF4alpha expression also have higher levels of HBsAg, HBcAg and HBV DNA. In contrast, in samples with higher levels of HNF3beta expression, levels of HBsAg, HBcAg and HBV DNA were lower. There was a positive correlation between HNF4alpha expression and HBV replication, and a negative correlation between HNF3beta expression and HBV replication, in the liver of chronic HBV-infected patients. This suggests that HNF4alpha and HNF3beta likely participate in HBV replication in patients with HBV infection, or that HBV replication may somehow influence the expression of HNF4alpha and HNF3beta in the liver.

Associations between hepatitis B virus mutations and the risk of hepatocellular carcinoma: a meta-analysis

Background

The association between hepatitis B virus (HBV) mutations and hepatocarcinogenesis remains controversial because of conflicting data in the literature. We conducted a meta-analysis of case–control and cohort studies to examine HBV PreS, enhancer II (EnhII), basal core promoter (BCP), and precore mutations in relation to the risk of hepatocellular carcinoma (HCC).

Methods

We searched databases for studies of these associations that were published in English or Chinese up to August 31, 2008. HBV mutation–specific odds ratios and relative risks were pooled by use of a random-effects model and stratified by potential confounders. All statistical tests were two-sided.

Results

Of the 43 studies included in this meta-analysis, 40 used a case–control design. The 43 studies evaluated a total of 11 582 HBV-infected participants, of whom 2801 had HCC. Statistically significant summary odds ratios of HCC were obtained for any PreS mutation (3.77, 95% confidence interval [CI] = 2.57 to 5.52), C1653T in EnhII (2.76, 95% CI = 2.09 to 3.64), T1753V (2.35, 95% CI = 1.63 to 3.40), and A1762T/G1764A in BCP (3.79, 95% CI = 2.71 to 5.29). PreS mutations were more strongly associated with an increased risk of HCC in subjects who were infected with HBV genotype C than in those who were infected with HBV genotype B, whereas the opposite was true for A1762T/G1764A. C1653T, T1753V, and A1762T/G1764A were more strongly associated with an increased risk of HCC in hepatitis B e antigen (HBeAg)–positive subjects than in HBeAg-negative subjects. PreS mutations, C1653T, T1753V, and A1762T/G1764A accumulated during the progression of chronic HBV infection from the asymptomatic carrier state to HCC (P_trend < .001 for each mutation). PreS mutations, C1653T, C1653T + T1753V, and A1762T/G1764A-based combinations of mutations had specificities greater than 80% for the prediction of HCC. The precore mutations G1896A and C1858T were not associated with the risk of HCC, regardless of HBeAg status and HBV genotype.

Conclusions

HBV PreS mutations, C1653T, T1753V, and A1762T/G1764A are associated with an increased risk of HCC. These mutations alone and in combination may be predictive for hepatocarcinogenesis.

Associations between hepatitis B virus mutations and the risk of hepatocellular carcinoma: a meta-analysis

BACKGROUND

The association between hepatitis B virus (HBV) mutations and hepatocarcinogenesis remains controversial because of conflicting data in the literature. We conducted a meta-analysis of case-control and cohort studies to examine HBV PreS, enhancer II (EnhII), basal core promoter (BCP), and precore mutations in relation to the risk of hepatocellular carcinoma (HCC).

METHODS

We searched databases for studies of these associations that were published in English or Chinese up to August 31, 2008. HBV mutation-specific odds ratios and relative risks were pooled by use of a random-effects model and stratified by potential confounders. All statistical tests were two-sided.

RESULTS

Of the 43 studies included in this meta-analysis, 40 used a case-control design. The 43 studies evaluated a total of 11 582 HBV-infected participants, of whom 2801 had HCC. Statistically significant summary odds ratios of HCC were obtained for any PreS mutation (3.77, 95% confidence interval [CI] = 2.57 to 5.52), C1653T in EnhII (2.76, 95% CI = 2.09 to 3.64), T1753V (2.35, 95% CI = 1.63 to 3.40), and A1762T/G1764A in BCP (3.79, 95% CI = 2.71 to 5.29). PreS mutations were more strongly associated with an increased risk of HCC in subjects who were infected with HBV genotype C than in those who were infected with HBV genotype B, whereas the opposite was true for A1762T/G1764A. C1653T, T1753V, and A1762T/G1764A were more strongly associated with an increased risk of HCC in hepatitis B e antigen (HBeAg)-positive subjects than in HBeAg-negative subjects. PreS mutations, C1653T, T1753V, and A1762T/G1764A accumulated during the progression of chronic HBV infection from the asymptomatic carrier state to HCC (P(trend) < .001 for each mutation). PreS mutations, C1653T, C1653T + T1753V, and A1762T/G1764A-based combinations of mutations had specificities greater than 80% for the prediction of HCC. The precore mutations G1896A and C1858T were not associated with the risk of HCC, regardless of HBeAg status and HBV genotype.

CONCLUSIONS

HBV PreS mutations, C1653T, T1753V, and A1762T/G1764A are associated with an increased risk of HCC. These mutations alone and in combination may be predictive for hepatocarcinogenesis.

Case-control study for the identification of virological factors associated with fulminant hepatitis B

BACKGROUND

Host and viral factors can promote the development of fulminant hepatitis B (FHB), but there have been no case-control studies for figuring out virological parameters that can distinguish FHB.

METHODS

In a case-control study, virological factors associated with the development of FHB were sought in 50 patients with FH developed by transient hepatitis B virus (HBV) infection (FH-T) and 50 with acute self-limited hepatitis B (AHB) who were matched for sex and age. In addition, 12 patients with FH developed by acute exacerbation (AE) of asymptomatic HBV carrier (ASC) (FH-C) were also compared with 12 patients without FH by AE of chronic hepatitis B (AE-C).

RESULTS

Higher HBV DNA levels, subgenotype B1/Bj, A1762T/G1764A, G1896A, G1899A and A2339G mutation were significantly more frequent (P < 0.05), while hepatitis B e-antigen was less frequent in the FH-T patients than AHB. In multivariate analysis, G1896A mutation (odds ratio [OR], 13.53; 95% confidence interval [CI], 2.75-66.64), serum HBV DNA more than 5.23 log copies/mL (OR, 5.14; 95% CI, 1.10-24.15) and total bilirubin more than 10.35 mg/mL (OR, 7.81; 95% CI, 1.77-34.51) were independently associated with a fulminant outcome by transient HBV infection. On the other hand, in comparison with the patients between FH-C and AE-C groups, there was no significant difference of virological factors associated with the development of FHB.

CONCLUSION

A number of virological factors have been defined that may distinguish FH-T from AHB in a case-control study. The pathogenic mechanism of FHB between transient HBV infection and AE of ASC would be different.

Chimeric constructs between two hepatitis B virus genomes confirm transcriptional impact of core promoter mutations and reveal multiple effects of core gene mutations

Hepatitis B virus (HBV) clone 4B replicated much more efficiently than clone 2A of the same genotype. Introduction of its T1753C, A1762T, G1764A, and C1766T core promoter mutations into the 2A genome greatly enhanced genome replication and suppressed HBeAg expression. Here we show that these effects are mediated by transcriptional up regulation of pregenomic RNA and suppression of precore RNA. Analysis of chimeric constructs suggested that the 5' end of the 2A core gene conferred higher level of pregenomic RNA, but less core protein and genome replication relative to the 4B sequence. Genome maturity of secreted virions was reduced by mutations present in the core protein of the 2A genome but enhanced by mutations found in the 4B core protein. The 4B core protein migrated faster than that of clone 2A. The possible links among the various phenotypes and the responsible mutations remain to be established.

Prevalence of basal core promoter and precore mutations in Chinese chronic hepatitis B patients and correlation with serum HBeAG titers

The A1762T and G1764A mutations in the basal core promoter (BCP) region and the G1896A mutation in the precore (PC) region of hepatitis B virus (HBV) genome are found commonly in HBeAg-negative patients. Experiments in vitro suggest that BCP and PC mutation reduce and abolish HBeAg expression, respectively. In the present study, the prevalence of the BCP and PC mutations were determined in 207 patients with HBeAg positive chronic hepatitis B from China and correlated with the titers of serum HBeAg. None of the patients received antiviral therapy. The HBV genotype was determined by direct sequencing of the HBsAg gene. The BCP and PC mutations were detected by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and confirmed by DNA sequencing. The HBeAg titer was measured by the microparticle enzyme immunoassay. Fifty-one of the 207 patients (24.6%) were infected with genotype B and the remainder with genotype C. The BCP mutations were detected in 103 patients (50%) while the PC mutation was present in 43 (20.8%). Thirteen patients (6.3%) harbored both BCP and PC mutations. No significant difference in the titers of HBeAg was found between patients infected with the two HBV genotypes, but the presence of either the BCP or PC mutation was associated with reduced HBeAg titer (P < 0.05). The presence of both the BCP and PC mutations was accompanied by even lower HBeAg titer (P < 0.05). These findings confirm that in patients with HBeAg, the BCP and PC mutations reduced the expression of HBeAg.

New approaches in the management of chronic hepatitis B: role of tenofovir

In the field of HIV management, tenofovir disoproxil fumarate (TDF) plays a pivotal role and has been demonstrated to be a safe and well-tolerated antiviral agent. Recent data showed the efficacy of TDF in the treatment of chronically hepatitis B virus (HBV)-infected patients. TDF was superior to adefovir dipivoxil (ADV) in both nucleos(t)ide-naïve HBeAg-positive and HBeAg-negative HBV patients, and appeared to be one of the most potent antiviral agents so far. In addition, several reports showed that TDF was also effective in the nucleos(t)ide-experienced population, although conflicting results have been presented concerning patients with genotypic resistance to ADV. TDF seems to have a good resistance profile as well. The rtA194T mutation in association with lamivudine resistance may confer resistance to TDF, although both in vivo and in vitro studies regarding this mutation demonstrate conflicting results. As treatment with TDF may be associated with nephrotoxicity, all TDF-treated patients should be monitored for renal function at baseline and periodically thereafter. While the relative roles of interferon vs nucleos(t)ide analogues (NA) as initial anti-HBV therapy remains unclear, TDF will probably become one of the key factors in HBV management both as first-choice NA for nucleos(t)ide-naïve patients and as rescue therapy for nucleos(t)ide-experienced patients.

Hepatitis B e antigen-negative mutations in the precore and core promoter regions in Korean patients

Most patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B have variants of the hepatitis B virus (HBV) that include mutations in the precore or core promoter regions of the HBV genome. The aim of this study was to investigate the patterns of precore and core promoter mutations and their relationship to HBeAg expression in Korean patients. Four hundred seventy-five Korean patients with chronic HBV infection between February 1995 and December 2003 were enrolled in this study. There were 236 HBeAg-positive and 239 HBeAg-negative patients. Blood samples were tested for HBsAg, anti-HBs, HBeAg, hepatitis B e antibody (anti-HBe), liver function tests, and serum HBV DNA. Mutations in the precore and core promoter regions were determined by direct sequencing. In the core promoter region, the C1740, C1753, T1762/A1764, and T1766 mutations were associated with HBeAg escape (all; P < 0.05). In the precore region, a higher frequency of the C1802, A1828, T1846, A1850, C1858, T1862, and A1896 mutations was found in HBeAg-negative patients (all; P < 0.05). In particular, the A1896 mutation was associated with high serum levels of ALT and HBV DNA in HBeAg-negative patients (P = 0.014 and 0.026, respectively). Mutations around the Kozak sequence (nucleotides 1809-1812) were found in 6.7% of patients and were not associated with undetectable HBeAg (P = 0.13). In Korean patients, various mutations in the precore and core promoter regions were associated with HBeAg escape and amelioration of hepatic inflammation in HBeAg- negative patients. Only the A1896 mutation contributed to HBeAg-negative chronic hepatitis B.

The rtA194T polymerase mutation impacts viral replication and susceptibility to tenofovir in hepatitis B e antigen-positive and hepatitis B e antigen-negative hepatitis B virus strains

Tenofovir is a new effective treatment option for patients with chronic hepatitis B, but could be potentially hampered by mutations in the hepatitis B virus (HBV) polymerase conferring drug resistance. Drug resistance may occur preferentially if long-term administration is required, for example, in patients with hepatitis B e antigen (HBeAg)-negative HBV infection bearing precore (PC) and basal core promoter (BCP) mutations. The rtA194T polymerase mutation has been found in HBV/HIV coinfected patients during tenofovir treatment and may be associated with tenofovir resistance. We generated replication-competent HBV constructs harboring rtA194T alone or in addition to lamivudine (LAM) resistance (rt180M + rtM204V), PC mutations, and BCP mutations and assessed their replicative capacity after transient transfection in human hepatoma cells. The rtA194T polymerase mutation alone or in conjunction with LAM resistance reduced the replication efficiency as compared with wild-type (WT) HBV. In contrast, combination of rtA194T (+/- LAM resistance) with HBeAg-negative PC or BCP mutants increased the replication capacity of the drug-resistant polymerase mutants, thereby restoring the viral replication to similar levels as WT clones. Clones harboring rtA194T showed partial resistance to tenofovir in vitro and also to LAM but remained susceptible to telbivudine and entecavir.

CONCLUSION

The rtA194T polymerase mutation is associated with partial tenofovir drug resistance and negatively impacts replication competence of HBV constructs. Viral replication, however, can be restored to WT levels, if these polymerase mutations occur together with precore or basic core promoter substitutions as found in HBeAg-negative hepatitis B. Patients with HBeAg-negative chronic HBV infection may therefore be at particular risk when developing drug resistance to tenofovir. Telbivudine or entecavir should be considered as effective alternative treatment options for these patients.

Hepatitis B virus basal core promoter mutation and DNA load correlate with expression of hepatitis B core antigen in patients with chronic hepatitis B

BACKGROUND

Expression of intrahepatic hepatitis B core antigen (HBcAg) is related to the immunopathogenesis of hepatitis B virus (HBV) infection. This study investigated the role that HBV genotype and basal core promoter (BCP) mutation play in the expression of HBcAg.

METHODS

A total of 70 hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis (genotype B in 52 patients and genotype C in 18 patients; BCP mutation T1762/A1764 in 16 patients) were enrolled. Clinical, virologic, and histologic features were compared with regard to localization and expression of intrahepatic HBcAg. The effects that HBV genotype and BCP mutation T1762/A1764 had on expression of HBcAg were further evaluated by in vitro assays.

RESULTS

Cytoplasmic, mixed cytoplasmic/nuclear, and nuclear localization of intrahepatic HBcAg was found in 38 (56.7%), 25 (37.3%), and 4 (6.0%) patients, respectively; HBcAg was not discernible in 3 patients. A total of 58 (82.9%) of these patients expressed a high level of HBcAg. In multivariate analysis, cytoplasmic localization of HBcAg correlated only with a low HBV load in serum (P = .045) and BCP mutation (P = .04). A high expression level of HBcAg also correlated with a high HBV load in serum (P = .015) and with BCP wild-type sequence (P = .037). In vitro assays indicated that the HBV BCP mutant strain had lower subcellular expression of HBcAg than did the BCP wild-type strain.

CONCLUSIONS

HBV BCP mutation and HBV load, but not genotype, contribute to the expression of intrahepatic HBcAg.

Prospective evaluation of hepatitis B 1762(T)/1764(A) mutations on hepatocellular carcinoma development in Shanghai, China

Chronic infection with the hepatitis B virus (HBV) is the most important risk factor for hepatocellular carcinoma (HCC). However, determinants of HCC risk in infected individuals are not well understood. We prospectively evaluated the association between acquired HBV 1762(T)/1764(A) double mutations and HCC risk among 49 incident HCC cases and 97 controls with seropositive hepatitis B surface antigen at baseline from a cohort of 18,244 men in Shanghai, China, enrolled during 1986 to 1989. Compared with HBV carriers without the mutations, chronic HBV carriers with the HBV 1762(T)/1764(A) double mutations experienced an elevated risk of HCC (odds ratio, 2.47; 95% confidence interval, 1.04-5.85; P = 0.04). Risk increased with increasing copies of the double mutations; men with > or =500 copies/microL serum had an odds ratio of 14.57 (95% confidence interval, 2.41-87.98) relative to those without the double mutations (P(trend) = 0.004). Thus, the HBV 1762(T)/1764(A) double mutation is a codeterminant of HCC risk for people chronically infected with HBV.

The association of HBV core promoter double mutations (A1762T and G1764A) with viral load differs between HBeAg positive and anti-HBe positive individuals: a longitudinal analysis

BACKGROUND/AIMS

Although there have been a few reports regarding the effect of basal core promoter (BCP) double mutations (A1762T and G1764A) on hepatitis B viral loads, the association remains uncertain. We aim to determine the association after controlling for HBeAg - a strong confounding factor.

METHODS

We selected randomly 190 individuals from a Chinese cohort of 2258 subjects for cross-sectional analysis and 56 of the 190 for longitudinal analysis of viral loads.

RESULTS

In multivariable analysis of the cross-sectional data, BCP double mutations are significantly associated with lower viral loads in HBeAg positive subjects but no difference was found in anti-HBe positive subjects. Triple mutations at nucleotide (nt) 1753, 1762 and 1764 and mutations between nt 1809 and 1817, precore stop mutation (nt 1896) and genotype are not associated with viral loads in either HBeAg or anti-HBe positive subjects. Analysis of the longitudinal data yielded similar results to the cross-sectional data. Viral loads differ significantly between individuals infected with wild-type and BCP double mutations prior to HBeAg seroconversion but this difference is lost after seroconversion.

CONCLUSIONS

BCP double mutations are associated with lower viral loads in HBeAg positive individuals but have no effect on the viral loads of anti-HBe positive individuals.

Sequential accumulation of the mutations in core promoter of hepatitis B virus is associated with the development of hepatocellular carcinoma in Qidong, China

BACKGROUND/AIMS

To investigate the mutations in hepatitis B virus (HBV) that might be related to hepatocellular carcinoma (HCC) in the high-risk area Qidong, China.

METHODS

DNA sequences of HBV basal core promoter (BCP) and the overlapping X gene were determined in 58 HCC and 71 chronic hepatitis (CH) patients. In addition, a consecutive series of plasma samples from 15 HCC cases were employed to compare the CP/X sequences before and after the occurrence of HCC.

RESULTS

T1762/A1764 double mutation was frequently found in Qidong patients, regardless of clinical status (65.5% in HCC and 73.2% in CH, P>0.05). Unexpectedly, the adjacent T1766/A1768 mutation significantly increased the risk of HCC (P<0.05). Moreover, the prevalence of triple mutations in BCP was significantly higher in patients with HCC than those with CH (P<0.05). The longitudinal study demonstrated that the mutations in BCP were gradually accumulated during the development of HCC. Colony formation assay showed while A1764 mutation alone did not alter the colony-inhibitory activity of HBx, double or triple mutations largely abrogated this effect.

CONCLUSIONS

The complex mutation involving T1766/A1768 was closely related to HCC. The enhanced risk of HCC caused by BCP variants could be attributable partially to the aberrant activity of HBx.

Adding interferon to lamivudine enhances the early virologic response and reversion of the precore mutation in difficult-to-treat HBV infection

BACKGROUND

The virologic impact of adding interferon to antiviral nucleoside therapy was studied in Japanese patients having perinatally transmitted hepatitis B virus (HBV) genotype C.

METHODS

Sixty-four patients including 41 positive for hepatitis B e antigen (HBeAg) were assigned to receive either (1) a combination of interferon-alpha (6 million units daily for 2 weeks, then three times weekly) plus lamivudine (100 mg daily) for 24 weeks followed by lamivudine alone for 28 weeks (n = 30) or (2) 52-week lamivudine monotherapy (n = 34).

RESULTS

The combination treatment enhanced the early virologic response, and HBV clearance was more frequent at week 8 for patients with baseline HBV DNA < or = 7 log copies/ml (90% vs. 33%, P = 0.013) and at week 24 for patients with baseline HBV DNA > 7 log copies/ml (75% vs. 40%, P = 0.080). In the combination arm, YMDD mutants emerged less often at week 52 (8% vs. 30%, P = 0.047). However, reversion of the precore mutation was more prominent with combination treatment than with monotherapy (McNemar test, P = 0.014 and P = 0.103, respectively). HBeAg seroconversion (P = 0.429) and sustained off-treatment HBV suppression to < or =5 log copies/ml (log-rank test, P = 0.195) were not improved.

CONCLUSIONS

Simultaneous commencement of treatment with interferon and a nucleoside analog may be worthy as a treatment option to augment the early virologic response and prevent drug resistance in difficult-to-treat patients. Combination treatment was also shown to enhance reversion of the precore mutation. Further studies are warranted to clarify the therapeutic implications of this phenomenon.

Associations between hepatitis B virus genotype and mutants and the risk of hepatocellular carcinoma

Background

The risk of hepatocellular carcinoma (HCC) increases with increasing level of hepatitis B virus (HBV) in serum (viral load). However, it is unclear whether genetic characteristics of HBV, including HBV genotype and specific genetic mutations, contribute to the risk of HCC. We examined the HCC risk associated with HBV genotypes and common variants in the precore and basal core promoter (BCP) regions.

Methods

From January 5, 1991, to December 21, 1992, baseline blood samples were collected from 2762 Taiwanese men and women who were seropositive for HBV surface antigen but had not been diagnosed with HCC; the samples were tested for HBV viral load by real-time polymerase chain reaction and genotyped by melting curve analysis. Participants who had a baseline serum HBV DNA level greater than 10⁴ copies/mL (n = 1526) were tested for the precore G1896A and BCP A1762T/G1764A mutants by direct sequencing. Incident cases of HCC were ascertained through follow-up examinations and computerized linkage to the National Cancer Registry and death certification profiles. A Cox proportional hazards model was used to estimate the risk of HCC associated with HBV genotype and precore and BCP mutants after adjustment for other risk factors. All statistical tests were two-sided.

Results

A total of 153 HCC cases occurred during 33 847 person-years of follow-up. The HCC incidence rates per 100 000 person-years for participants infected with HBV genotype B or C were 305.6 (95% confidence interval [CI] = 236.9 to 388.1) and 785.8 (95% CI = 626.8 to 972.9), respectively. Among participants with a baseline HBV DNA level of at least 10⁴ copies/mL, HCC incidence per 100 000 person-years was higher for those with the precore G1896 (wild-type) variant than for those with the G1896A variant (955.5 [95% CI = 749.0 to 1201.4] vs 269.4 [95% CI = 172.6 to 400.9]) and for those with the BCP A1762T/G1764A double mutant than for those with BCP A1762/G1764 (wild-type) variant (1149.2 [95% CI = 872.6 to 1485.6] vs 358.7 [95% CI = 255.1 to 490.4]). The multivariable-adjusted hazard ratio of developing HCC was 1.76 (95% CI = 1.19 to 2.61) for genotype C vs genotype B, 0.34 (95% CI = 0.21 to 0.57) for precore G1896A vs wild type, and 1.73 (95% CI = 1.13 to 2.67) for BCP A1762T/G1764A vs wild type. Risk was highest among participants infected with genotype C HBV and wild type for the precore 1896 variant and mutant for the BCP 1762/1764 variant (adjusted hazard ratio = 2.99, 95% CI = 1.57 to 5.70, P < .001).

Conclusions

HBV genotype C and specific alleles of BCP and precore were associated with risk of HCC. These associations were independent of serum HBV DNA level.

Application of a novel, rapid, and sensitive oligonucleotide ligation assay for detection of cancer-predicting mutations in the precore and basal core promoter of hepatitis B virus

Hepatocellular carcinoma (HCC) and cirrhosis are important causes of mortality worldwide. Persistent hepatitis B virus (HBV) infection is a major cause of these diseases. Double mutations in the basal core promoter (BCP) (A1762T and G1764A) and precore (pre-C) (G1896A) regions of the virus are associated with progression to HCC. The current study is aimed at developing a simple method for screening and detecting BCP and pre-C mutations in HBV carriers. We have developed and validated an oligonucleotide ligation assay (OLA) to detect point mutations in the HBV core gene. We have applied OLA methods to samples from HBV-infected carriers recruited from the Gambia Liver Cancer Study (GLCS) comprising asymptomatic HBsAg carriers, patients with cirrhosis, and patients with HCC. We observed an 89.3% and 95.8% concordance between the OLA and DNA sequencing for BCP and pre-C mutations, respectively. OLA detected the mutations in single-strain infections and in infections with mixtures of wild-type and mutant viruses under conditions where sequencing detected only the single dominant strains. BCP mutations were detected in 75.7% of patients with advanced liver disease (cirrhosis/HCC) compared to 47.6% of asymptomatic carriers, while pre-C mutations were detected in 34.5% of advanced liver disease patients and in 47.6% of asymptomatic HBsAg carriers. There was a significant association between the presence of BCP mutations and advanced liver disease. In conclusion, OLA is a simple, economical, and reliable assay for detection of pre-C and BCP mutations. Its application can lead to improvement in diagnosis and clinical care in regions where HBV is endemic.

A complete genomic analysis of hepatitis B virus genotypes and mutations in HBeAg-negative chronic hepatitis B in China

We aimed to study the distribution of hepatitis B virus (HBV) genotypes/subgenotypes in different parts of China and their clinical impact on the severity of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. Residual serum samples from a cohort of HBeAg-negative chronic hepatitis B patients in Hong Kong, Shanghai and Beijing were studied. Complete HBV genomic sequencing was performed for phylogenetic tree analysis and determination of HBV mutations was carried out. Mutations associated with severe liver fibrosis (Ishak score 4 or more) were selected by computerized information gain criteria. Genotype B (all subgenotype Ba) HBV was present in 19 of 45 (42%), 12 of 31 (39%) and 5 of 25 (20%) patients in Hong Kong, Shanghai and Beijing, respectively (P = 0.16). Ninety-seven per cent of genotype C HBV in Shanghai and Beijing belonged to subgenotype Ce whereas 69% of genotype C patients in Hong Kong belonged to subgenotype Cs (P < 0.001). Patients infected by subgenotype Cs had the lowest serum albumin and highest alanine aminotransferase levels compared with subgenotype Ce and Ba. Patients infected by subgenotype Cs also had more severe histological necroinflammation than subgenotype Ce. Two HBV mutations were identified to associate with severe liver fibrosis (G2858C and C2289A) and one mutation was protective against severe liver fibrosis (T2201C). The T2201C mutation was found exclusively among patients (21 of 46 patients, 45%) infected by HBV subgenotype Ce. The clinical differences in HBeAg-negative chronic hepatitis B in China may be influenced by different distribution of subgenotype C HBV.

Role of hepatitis B virus genotypes and quantitative HBV DNA in metastasis and recurrence of hepatocellular carcinoma

Identification of risk factors for recurrence and metastasis of HCC is important for the prognosis of HCC surveillance in chronic HBV infection. In this article, 125 HCC patients recruited were followed up prospectively for tumor metastasis and recurrence for a median of 104 (10-130) weeks. HBV DNA level was detected by LightCycler-based real-time fluorescence quantitative polymerase chain reaction-restriction system. HBV genotypes were determined by using PCR restriction-fragment length polymorphism. BCP and PC mutations were performed by PCR and direct sequencing of amplified products. Among 125 HCC patients, 19 patients were excluded because of the lack of follow-up data and the remaining 106 patients were followed up of 2 years and entered into analysis. Sixty-nine patients had tumor metastasis or recurrence during the follow-up and the cumulative probability of HCC metastasis or recurrence was 65.1%. On multivariate analysis, genotype C and HBV DNA level were the risk factors for HCC recurrence or metastasis. The incidence of recurrence or metastasis increased with baseline HBV DNA level in a dose-response relationship ranging from 22% for HBV DNA level of less than 3 log10 copies/ml to 80% for HBV DNA level of 5 log10 copies/ml or greater (P = 0.012). Fifty-seven (74.0%) and 12 (41.4%) patients had metastasis or recurrence in patients with genotype C and B, respectively. The adjusted OR of recurrence or metastasis for genotype C compared with genotype B was 9.755 (P = 0.009). In conclusion, elevated HBV DNA level and genotype C are strong risk predictors of HCC metastasis or recurrence.

Effect of basal core promoter and pre-core mutations on hepatitis B virus replication

There are two hypotheses explaining a fulminant outcome after hepatitis B virus (HBV) infection, both of which may be applicable at the same time: (i) basal core promoter (BCP) mutations increase viral replication, allowing rapid spread of the virus through the liver, and (ii) pre-core (pre-C) mutations abrogating hepatitis B e antigen (HBeAg) synthesis remove its tolerogenic effect, leading to a vigorous immune response. This study investigated the effect of these mutations on virus replication efficiency and HBeAg production. Substitutions A1762T/G1764A and T1753C, C1766T and T1768A in the BCP region, and G1896A and G1899A in the pre-C region, were examined either alone or in combination, using a common genetic background. Huh7 cells were transfected with these constructs and real-time PCR was used to quantify released virion-associated and intracellular HBV DNA, pregenomic RNA and pre-C mRNA. In addition, culture supernatants were tested for hepatitis B surface antigen (HBsAg) and HBeAg. The double BCP mutation (A1762T/G1764A) and the pre-C mutations (G1896A, G1899A), either alone or in combination, had no appreciable effect on the replication capacity of the virus. In contrast, clones with mutations at positions 1766/1768, 1762/1764/1766 and 1753/1762/1764 exhibited increased-replication phenotypes. HBeAg was undetectable in all cultures transfected with constructs bearing the G1896A stop-codon mutation, as expected. In contrast, constructs with additional mutations in the BCP region had appreciably lower levels of HBeAg expression than the wild type. Thus, core promoter mutations other than those at 1762/1764 appear to upregulate viral DNA replication and, at the same time, greatly reduce HBeAg production.

Non-A hepatitis B virus genotypes in antenatal clinics, United Kingdom

In the United Kingdom, the National Screening Programme for identification of hepatitits B virus (HBV) infection in pregnant women uses HBV e antigen (HBeAg) and antibody to HBeAg (anti-HBe) as markers of infectivity to determine use of immunoglobulin for hepatitis B. Serum samples from 114 HBV-infected women were analyzed. Viral loads correlated with HBeAg/anti-HBe status and viral genotypes. Among 95 mothers whose serum contained anti-HBe, viral loads ranged between undetectable and 8.6 x 10(6) IU/mL (median 228 IU/mL). Ten (10.5%) of these mothers had plasma viral loads >10(4) IU/mL; 6 were infected with genotype E and one each with genotypes A, B, C, and D. All viruses had precore stop codon or basal core promoter mutations. Preponderance of genotypes other than A among antenatal mothers in the United Kingdom reflects increasing globalization and trends in immigration. HBeAg serostatus is no longer sufficiently accurate for inferring potential infectivity of pregnant HBV carriers.

Virological and clinical implication of core promoter C1752/V1753 and T1764/G1766 mutations in hepatitis B virus genotype D infection in Mongolia

BACKGROUND AND AIM

The aim of the present study was to reveal virological and clinical features of hepatitis B virus (HBV) genotype D infection.

METHODS

One hundred and twenty-two Mongolian chronic liver disease (CLD) patients infected with HBV were subjected for serological HBV-markers screening and HBV-enzyme immunoassay (EIA) genotyping. Nucleotide sequences were analyzed for 48 HBV/D strains (23 isolated from hepatocellular carcinoma (HCC) and 25 from CLD patients).

RESULTS

Prevalence of hepatitis B e antigen (HBeAg) positivity was low (25.9%) in young patients (< or =30 years old) indicating early HBeAg seroclearance in HBV/D carriers. The T1764/G1766 double mutation was the most common basal core promoter (BCP) mutation (29.2%) and was frequent in HBeAg-negative patients (39.3%). Patients harboring T1764/G1766 mutants exhibited lower HBV-DNA and HBV core antigen (HBcAg) levels than those with wild-type BCP strains (P = 0.024, 0.049, respectively). C1752 and/or V (not T) 1753 mutation was significantly prevalent in HCC patients (HCC vs CLD; 52.2% vs 20%, P = 0.033). T1762/A1764 mutation was detected in 75.0% of HCC patients with high viral load (> or =5 log copies/mL). Precore stop codon mutation A1896 was detected in (70.8%) of HBV/D-infected patients.

CONCLUSIONS

In Mongolians infected with HBV/D, C1752 and/or V1753 mutation was associated with HCC.

Epidemiological and clinical evaluation of hepatitis B, hepatitis C, and delta hepatitis viruses in Tajikistan

The implication of genotypes is recognized increasingly in the clinical course of hepatitis B virus (HBV) and in response to anti-viral drugs of hepatitis C virus (HCV). Genotypic prevalence of both etiological agents varies geographically and no data are available for Tajikistan. To investigate the epidemiology and clinical significance of HBV and HCV genotypes in chronic hepatitis (group 1) and liver cirrhosis/hepatocellular carcinoma (HCC) (group 2) patients in Tajikistan, 124 patients with chronic liver disease (group 1 = 84 and group 2 = 40) were enrolled. Genotypes of HBV, HCV, and delta hepatitis virus (HDV) were determined by sequencing. The overall prevalence of anti-HCV, HCV core antigen (HCVcAg) and HBsAg was 46% (57/124) and 41.1% (51/124), respectively. Coinfection of HCV/HBV, HBV/HDV, and HCV/HBV/HDV was found in 4.8% (6/124), 11.2% (12/124), and 0.8% (1/124) of cases, respectively. HDV genotype 1 was found in 19.6% (10/51) of HBsAg-positive patients. The HBV/HDV coinfection was relatively high in group 2 compared to group 1 (15% vs. 7.1%). HCV/1b detected in 84.6% (44/52) of HCV RNA-positive patients, followed by 3a (7.6%), 2a (5.7%), and 2c (1.9%). HBV/D was detected in 94.1% (48/51) of HBsAg-positive patients, followed by HBV/A [5.8% (3/51)]. T1762/A1764 double mutation was associated with liver cirrhosis/HCC in HBV-infected patients (P = 0.0004). This is the first study on the molecular epidemiology of hepatitis viruses among chronic liver diseases patients in Tajikistan. Among HBV-infected patients, the T1762/A1764 mutation was associated with liver cirrhosis/HCC.

A population-based study to investigate host genetic factors associated with hepatitis B infection and pathogenesis in the Chinese population

BACKGROUND

Hepatitis B virus (HBV) infection is a significant public health problem that may lead to chronic liver disease, cirrhosis, and hepatocellular carcinoma (HCC). Approximately 30% of the world's population has been infected with HBV and approximately 350 million (5-6%) are persistent carriers. More than 120 million Chinese are infected with HBV. The role of host genetic factors and their interactions with environmental factors leading to chronic HBV infection and its complications are not well understood. We believe that a better understanding of these factors and interactions will lead to more effective diagnostic and therapeutic options.

METHODS/DESIGN

This is a population-based, case-control study protocol to enroll 2200 Han Chinese from medical centers in northern and western China. Adult subjects in the following groups are being enrolled: healthy donors (n = 200), HBV infected persons achieving virus clearance (n = 400), asymptomatic HBV persistent carriers (n = 400), chronic hepatitis B cases (n = 400), decompensated liver cirrhosis with HBV infection cases (n = 400), and hepatocellular carcinoma with HBV infection cases (n = 400). In addition, for haplotype inference and quality control of sample handling and genotyping results, children of 1000 cases will be asked to provide a buccal sample for DNA extraction. With the exception of adult patients presenting with liver cirrhosis or HCC, all other cases and controls will be 40 years or older at enrollment. A questionnaire is being administered to capture dietary and environmental risk factors. Both candidate-gene and genome-wide association approaches will be used to assess the role of single genetic factors and higher order interactions with other genetic or environmental factors in HBV diseases.

CONCLUSION

This study is designed and powered to detect single gene effects as well as gene-gene and environmental-gene interactions. The identification of allelic polymorphisms in genes involved in the pathway leading to chronic viral infection, liver cirrhosis and, ultimately, hepatocellular carcinoma would provide insights to those factors leading to HBV replication, liver inflammation, fibrosis, and the carcinogenic process. An understanding of the contribution of host genetic factors and their interactions may inform public health policy, improve diagnostics and clinical management, and provide targets for drug development.

Collective repression of the hepatitis B virus enhancer II by human TR4 and TR2 orphan receptors

AIM

The human testicular receptor 4 and 2 (TR4 and TR2) orphan receptors are members of the nuclear receptor superfamily that regulate target gene expression via binding to the consensus AGGTCA direct repeats of the hormone response elements. Previous studies have reported that TR4 and other nuclear receptors could bind to the direct repeat 1 element of the hepatitis B virus (HBV) core promoter.

METHODS

Differential gene expression of HBV caused by TR4 and TR2 was determined by gel retardation and functional assays.

RESULTS

Electrophoretic mobility shift assay demonstrated that TR4 and TR2 might bind to the direct repeat 6 element of the HBV enhancer II region. RESULTS of the dual-luciferasereporter gene assay showed that TR4 and TR2 might significantly suppress HBV gene expression through this direct repeat 6 element in the enhancer II.

CONCLUSION

These results implied that TR4 together with its heterodimer partner TR2 could collectively play a significant role in the transcriptional suppression of HBV gene expression via the direct repeat 6 element in the enhancer II. Therefore, the application of nuclear receptors potentially may be antiviral agents in chronic HBV infection.

Hepatitis B virus genotypes: natural history and implications for treatment

There are eight different genotypes named A-H. Genotypes have distinct geographic distribution in different regions of the world. There exists a difference in the disease profile between different genotypes. Genotype A compared with D, and B compared with C have earlier hepatitis B e-antigen seroconversion and less severe liver disease. However, genotypes are closely linked with core promoter and precore mutations. This may have a confounding effect on the association of genotypes with disease progression. Patients with genotype A compared with D and B compared with C have a better treatment response to IFN-alpha. However, there are no differences in the treatment response and rate of emergence of drug-resistant hepatitis B virus between different genotypes to nucleoside/nucleotide analog therapy.

Pre-S deletion and complex mutations of hepatitis B virus related to advanced liver disease in HBeAg-negative patients

BACKGROUND & AIMS

This longitudinal study investigated the interactions and roles of hepatitis B virus (HBV) genotypes, pre-S deletions, and core promoter and precore mutations on the progression of liver disease in hepatitis B e antigen (HBeAg)-negative patients.

METHODS

A total of 141 HBeAg-negative patients without liver cirrhosis or hepatocellular carcinoma at study entry were recruited for this study, including 45 inactive HBV carriers and 96 patients with HBeAg-negative chronic hepatitis B. The HBV genotypes and the sequences of pre-S, core promoter, and precore regions were determined.

RESULTS

Compared with patients without developing liver cirrhosis, patients with the development of liver cirrhosis had higher rates of genotype C; pre-S deletions; C or G1753, T1762/A1764, T1766, and/or A1768 mutants; and G1799 variant. Cox regression analysis showed that older age, higher total bilirubin and HBV DNA levels, pre-S deletions, and T1766 and/or A1768 mutants were significantly associated with the development of liver cirrhosis. HBV with a complex mutation pattern (pre-S deletion, T1762/A1764, and T1766 and/or A1768 mutants) rather than a single mutation was associated with the development of liver cirrhosis, and the patterns of mutation combinations differed between HBV genotype B and C. Moreover, pre-S deletion was a significant risk factor for hepatocellular carcinoma.

CONCLUSIONS

This study indicated that pre-S deletion and combined mutations of HBV are useful molecular markers for predicting the clinical outcomes of HBeAg-negative patients.

Differences of YMDD mutational patterns, precore/core promoter mutations, serum HBV DNA levels in lamivudine-resistant hepatitis B genotypes B and C

The aims of this study were to investigate the viral differences among lamivudine-resistant hepatitis B virus (HBV) genotypes B and C in vivo. Fifty-three patients carrying lamivudine-resistant HBV were enrolled in this study. HBV genotypes, Levels of alanine aminotransferase (ALT), HBV DNA levels were monitored during therapy. The polymerase and precore/core promoter genes were amplified by polymerase chain reaction and their products were sequenced directly. Among 53 patients resistant HBV genotypes B and C accounted for 41.50% and 58.50%, respectively. The occurrence of reverse transcriptase rt204I mutants was lower in genotype B (36.36%) than that in genotype C (87.10%), whereas rt204V mutants was higher in genotype B (63.64%) than that in genotype C (12.90%). The occurrence of precore mutation (nt1896A) was higher in genotype B (77.27%) than that in genotype C (32.26%). Serum HBV DNA levels after emergence of lamivudine resistance were higher in genotype C (7.71 +/- 0.80 Log copies/mL) compared with genotype B (6.97 +/- 0.77 Log copies/mL). Multivariate analysis identified pretreatment HBV DNA levels, HBeAg status and HBV genotype as independent factors associated with a shorter time to lamivudine resistance(P = 0.035, P = 0.006 and P = 0.001, respectively). Multivariate analysis showed that HBV genotype (P = 0.004) and pretreatment ALT levels (P = 0.01) was independently associated with YMDD mutational patterns. The results showed that the YMDD mutational patterns, precore mutation and serum HBV DNA levels differ between lamivudine-resistant HBV genotypes B and C in vivo. It is valuable for treatment of lamivudine-resistant HBV in clinic.

Five subgenotypes of hepatitis B virus genotype B with distinct geographic and virological characteristics

Several hepatitis B virus (HBV) subgenotypes, HBV/A1, A2, Bj and Ba, have been reported with respect to clinical differences among patients infected with these subgenotypes. The population genetics and phylogeography of HBV were investigated based on the complete genome sequences of 484 isolates with 108 from our chronic hepatitis B patients and the remaining from the GenBank database. Besides genotypes A-H (HBV/A-H), five subgenotypes were identified among 169 HBV/B isolates by phylogenetic analysis and nucleotide divergence. There were 27 isolates of subgenotype B(1) (HBV/B(1)) restricted to Japan, 104 isolates of HBV/B(2) with the widest distribution in most Asian countries, 4 isolates of HBV/B(3) restricted to Indonesia, 32 isolates of HBV/B(4) restricted to Vietnam, and 7 isolates of HBV/B(5) restricted to Philippines. HBV/B(2)-B(5) isolates carried a recombination with HBV/C over the precore and core genes. In addition to the characteristics of HBV/B(1)-B(5) at some cis-acting elements, the precore stop-codon mutant (G1896A) was significantly different among HBV/B(1), HBV/B(2), and HBV/B(4) (70.3%, 31.7%, 53.0%, P=0.001), while no such mutation was found in HBV/B(3) and B(5). Among characteristics of the HBV/B(1)-B(5) amino acid sequences, serotype adw (K(122)) was exclusive among HBV/B(1), HBV/B(2), and HB V/B(3) isolates, while serotype ayw (R(122)) was among the HBV/B(4) and HBV/B(5) isolates. Furthermore, distinct variations of T cell and B cell recognition epitopes within surface and core proteins were also found among these subgenotypes. In conclusion, subgenotypes HBV/B(1)-B(5) exhibited distinct geographical distributions, virologic characteristics, and probable clinical implications.

Type B fulminant hepatitis is closely associated with a highly mutated hepatitis B virus strain

OBJECTIVE

Genome-wide sequences of hepatitis B virus strain associated with type B fulminant hepatitis have not been compared with those of acute self-limited hepatitis. We carried out full-length sequencing analysis of viral strains derived from patients with type B acute liver injury.

METHODS

Nine acute self-limited hepatitis and 6 fulminant hepatitis patients were the subjects of this study. Full-length sequencing analysis of viral DNA was done by PCR-direct sequencing.

RESULTS

Higher frequencies in fulminant hepatitis strains compared with acute hepatitis ones were observed in the T1762/A1764 (p < 0.05), A1896 (p = 0.09) and M1753 (M = C or A) (p = 0.09) mutations. Viruses related to fulminant hepatitis possessed the higher number of nucleotide substitutions than those related to acute hepatitis in the whole virus genome (p < 0.01) and various regions including preS/S gene (p < 0.05), precore/core gene (p < 0.01), polymerase gene (p < 0.05) and basic core promoter/core upstream regulatory sequence (p < 0.01). The high number of nucleotide substitutions in viruses related to fulminant hepatitis was predominantly non-synonymous in the preS/S and precore/core genes.

CONCLUSION

Development of type B fulminant hepatitis may be associated with a highly mutated hepatitis B virus strain.

Hepatitis B virus DNA prediction rules for hepatitis B e antigen-negative chronic hepatitis B

After hepatitis B e antigen (HBeAg) seroconversion, hepatitis B may become inactive or progress to HBeAg-negative hepatitis with persistent or intermittent alanine aminotransferase (ALT) elevation. The aim of this study was to prospectively identify factors predictive of the clinical course in HBeAg-negative chronic hepatitis B (CHB). Patients were stratified by ALT and HBeAg status and followed every 3 months for up to 5 years. Kaplan-Meier and Cox regression analysis using the change from normal ALT to elevated ALT as endpoints were performed to determine factors associated with ALT elevation/normalization. Seventy-four HBeAg-negative and 32 HBeAg-positive patients were prospectively evaluated. For HBeAg-negative patients, hepatitis B virus (HBV) DNA was predictive of future ALT. Only 1 patient with normal ALT and an HBV DNA value lower than 10,000 copies/mL developed an elevated ALT within the subsequent year, whereas 67% with an HBV DNA value greater than 100,000 copies/mL had a rise in ALT above normal within 1 year. Patients with a previous history of ALT elevation and longer follow-up at all levels of HBV DNA were more likely to experience ALT elevations. For HBeAg-negative patients with elevated ALT and all HBeAg-positive patients, HBV DNA did not predict future ALT. Other viral and host factors were not predictive of future ALT.

CONCLUSION

HBeAg-negative CHB has a fluctuating course. HBV DNA values lower than 10,000 copies/mL predict persistently normal ALT for at least 1 year. Patients with HBV DNA values between 10,000 and 100,000 copies/mL can safely be followed at 6 monthly intervals, whereas HBV DNA values greater than 100,000 copies/mL are highly predictive of future ALT elevation and should prompt regular follow-up.

Sequential treatment with lamivudine and alpha-interferon in anti-HBe-positive chronic hepatitis B patients: a pilot study

BACKGROUND

In chronic hepatitis B, long-term use of alpha interferon is hampered by side effects, and long-term treatment with nucleos(t)ide analogues is burdened by drug-resistant mutants. We hypothesized that alternate rounds of lamivudine and alpha interferon might circumvent previous shortcomings.

AIM

To evaluate efficacy of sequential lamivudine or IFN-alpha2b monotherapies in preventing occurrence of tyrosine-methionine-aspartate-aspartate (YMDD) mutants and achieving virological and biochemical response.

METHODS

Fifteen patients with hepatitis B surface antigen, anti-HBe-positive chronic hepatitis received four consecutive rounds of monotherapy with lamivudine (100 mg/day), IFN-alpha2b (5MU/tiw), lamivudine, IFN-alpha2b. Serum HBV-DNA levels were evaluated during and off treatment, HBV polymerase and pre-core/core regions sequenced.

RESULTS

End-of-treatment response was achieved in 10 patients (67%). One patient did not respond, a second developed genotypic resistance at week 24. A rebound in viremia occurred in three patients at week 48. Six patients (40%) remained sustained responders. Triple promoter mutations at nucleotides 1762-1764-1896 prevailed in non-responders (60%) as compared to responders (20%). L180M/M204V mutations were identified during virological breakthrough.

CONCLUSION

Sequential approach of alternate rounds of lamivudine or interferon may help patients to tolerate a prolonged schedule of therapy and protect them from emergence of viral strains.

Critical role of the 36-nucleotide insertion in hepatitis B virus genotype G in core protein expression, genome replication, and virion secretion

Frequent coinfection of hepatitis B virus genotype G with genotype A suggests that genotype G may require genotype A for replication or transmission. In this regard, genotype G is unique in having a 12-amino-acid extension in the core protein due to a 36-nucleotide insertion near the core gene translation initiation codon. The insertion alters base pairing in the lower stem of the pregenome encapsidation signal, which harbors the core gene initiator, and thus has the potential to affect both core protein translation and pregenomic RNA encapsidation. Genotype G is also unusual for possessing two nonsense mutations in the precore region, which together with the core gene encode a secreted nonstructural protein called hepatitis B e antigen (HBeAg). We found that genotype G clones were indeed incapable of HBeAg expression but were competent in RNA transcription, genome replication, and virion secretion. Interestingly, the 36-nucleotide insertion markedly increased the level of core protein, which was achieved at the level of protein translation but did not involve alteration in the mRNA level. Consequently, the variant core protein was readily detectable in patient blood. The 12-amino-acid insertion also enhanced the genome maturity of secreted virus particles, possibly through less efficient envelopment of core particles. Cotransfection of genotypes G and A did not lead to mutual interference of genome replication or virion secretion. Considering that HBeAg is an immunotolerogen required for the establishment of persistent infection, its lack of expression rather than a replication defect could be the primary determinant for the rare occurrence of genotype G monoinfection.

Impaired intrahepatic hepatitis B virus productivity contributes to low viremia in most HBeAg-negative patients

BACKGROUND & AIMS

Knowledge of factors regulating transcriptional activity of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) may help in understanding mechanisms of viral decay and how these processes are thwarted in chronically HBV-infected patients.

METHODS

Liver biopsies from 119 treatment-naive chronically infected patients (42 HBeAg-positive and 77 HBeAg-negative) were determined for HBV transcriptional and replicative activity.

RESULTS

Significantly lower median serum HBV DNA (-4 log), intrahepatic HBV DNA (-2 log), and cccDNA (-1 log) amounts were measured in HBeAg-negative versus HBeAg-positive patients. Despite a good correlation found between intrahepatic amounts of progeny virions and serum HBV DNA in all patients, cccDNA levels did not correlate with serum titers in HBeAg-negative individuals. Analysis of HBV RNA transcripts showed that impaired virion productivity in HBeAg-negative individuals was due to lower steady-state levels of pregenomic RNA produced per cccDNA. Interestingly, preS/S RNA levels and serum HBsAg concentrations did not differ between HBeAg-positive and HBeAg-negative patients when normalized for cccDNA contents, showing that subviral particle production was not impaired in HBeAg-negative patients and correlated with cccDNA levels. Although the majority of HBeAg-negative individuals harbored cccDNA with common precore and/or basal core promoter mutations, occurrence of these variants was not responsible for reduced viral replication. Instead, replacement of wild-type cccDNA with core promoter mutants reestablished high virion productivity.

CONCLUSIONS

Lower viremia in HBeAg-negative individuals is not only due to lower cccDNA content but also to impaired virion productivity, which can arise without emergence of HBeAg variants and without affecting HBsAg production.

Genetic characteristics of hepatitis B virus genotypes as a factor for interferon-induced HBeAg clearance

The factors determining the responsiveness of different hepatitis B virus (HBV) genotypes to interferon treatment are not fully understood. We investigated the relationship between HBV genetic characteristics and the outcome of short (16 weeks) or prolonged (32 weeks) treatment with standard interferon-alpha in a prospectively followed cohort of 103 patients across Europe with HBeAg positive chronic hepatitis B. INNO-LiPA assays and HBV DNA sequencing were used to determine HBV genotypes, mutations in the core promoter and precore/core regions. After 16-weeks interferon-alpha treatment, the rate of HBeAg clearance was higher in genotype A versus all other genotypes (P = 0.014), or genotype D alone (P = 0.05). The HBV genome analysis revealed that: (i) after 16-weeks treatment, an HBV subpopulation with core promoter mutations emerged or increased (P < 0.001) only in genotype A; (ii) the core gene of genotype A has the lowest number of amino acid variations in comparison with genotypes B, C, or D. Logistic regression analysis identified genotype A as a positive predictor of short (16 weeks) treatment response (P = 0.001; odds ratio 6.19, 95 confidence interval 1.94-19.8), having a greater impact than baseline HBV DNA or alanine aminotransferase (ALT) levels. In contrast, the response to prolonged interferon-alpha treatment was not different between HBV genotypes. These results suggest that HBV genotype A responds earlier to interferon treatment than other genotypes, which is associated with its molecular characteristics. The optimal duration of interferon-based therapies in chronic hepatitis B may vary between different HBV genotypes.

Clinical significance and evolution of core promoter and precore mutations in HBeAg-positive patients with HBV genotype B and C: a longitudinal study

BACKGROUND/AIMS

The aims of this longitudinal study were to investigate whether the clinical outcome and evolution of core promoter and precore mutations were different during hepatitis B e antigen (HBeAg) seroconversion between hepatitis B virus (HBV) genotypes B and C in HBeAg-positive patients with chronic hepatitis B.

PATIENTS AND METHODS

The core promoter and precore sequences were determined from serial sera of 156 HBeAg-positive patients with chronic HBV infection.

RESULTS

In HBV genotype C, the T1762/A1764 mutant was detected earlier than the A1896 mutant, and the frequency was significantly higher than in HBV genotype Ba over the entire follow-up period. In HBV genotype Ba, A1896 was found earlier than the T1762/A1764 mutant, and the frequency was significantly higher than in genotype C only before HBeAg seroconversion, and the A1896 mutant played an important role in HBeAg seroconversion in HBV genotype Ba. In addition, the T1846 variant was an independent factor associated with HBeAg seroconversion. Furthermore, HBV genotype C was associated with the development of G or C1753 and T1766/A1768 mutations, and the reactivation of hepatitis after HBeAg seroconversion. Based on Cox's regression analysis, the significant risk factors of liver cirrhosis were older age at entry [hazard ratio (HR)=1.085, 95% confidence interval (CI)=1.036-1.136, P=0.001], alanine transaminase (ALT) >80 U/l (HR=3.48, 95% CI=1.37-8.86, P=0.009), and the T1762/A1764 mutant (HR=5.54, 95% CI=2.18-14.08, P<0.001).

CONCLUSIONS

Our study showed that different HBV genotypes were associated with various mutations in the core promoter and precore regions during HBeAg seroconversion. T1762/A1764 mutation could be useful in predicting clinical outcomes in HBeAg-positive patients with HBV infection.

Presence of hepatitis B virus core promoter mutations pre-seroconversion predict persistent viral replication after HBeAg loss

BACKGROUND

In patients with chronic hepatitis B virus (HBV) infection DNA levels do not always fall after anti-hepatitis B e (anti-HBe) seroconversion.

OBJECTIVES

To follow longitudinally through HB e antigen (HBeAg) loss HBV DNA levels and core promoter/precore sequences in a cohort of 21 chronic HBV carriers.

STUDY DESIGN

Treatment-naïve HBeAg seropositive HBV carriers were monitored through HBeAg loss for between 2 and 22 years (mean 9.3). Core promoter/precore sequences, genotypes, HBV DNA levels and HBe status were determined.

RESULTS

Patients were grouped into those in whom serum/plasma HBV DNA remained high after HBeAg loss (group 1, n=11; HBV DNA>5log(10)IU/ml) and those in whom HBV DNA declined (group 2, n=10). Re-appearance of HBeAg was seen in seven group 1 patients. Pre-seroconversion mutations in the core promoter region including A1762T and/or G1764A were detected more frequently in group 1 (P=0.031). Overall sequence changes at sites other than 1762/1764 were more common post-seroconversion in group 1 than group 2 patients (P=0.037).

CONCLUSIONS

The presence of core promoter mutations prior to HBeAg loss identified those patients in whom HBV DNA persisted at high levels and was associated with temporary re-emergence of serum HBeAg. These patients may benefit from early anti-viral treatment.

Impact of viral genotypes and naturally occurring mutations on biological properties of hepatitis B virus

Hepatitis B patients worldwide are infected with different viral genotypes. Within the same individual the dominant viral species evolves over the course of chronic infection to generate viral variants or mutants. The mutations, often selected by the host immune response or antiviral therapy, are sometimes restricted by viral genotypes. We are interested in characterizing mutations that affect the expression of hepatitis B e-antigen (HBeAg), a protein with a large effect on duration of infection and severity of liver diseases. HBeAg is encoded by the precore region in addition to the core gene. Core promoter mutations reduce HBeAg expression at the transcriptional level. We found that the hot spot mutations (A1762T/G1764A) only mildly reduced HBeAg expression and enhanced genome replication, while incorporation of additional core promoter mutations intensified both phenotypes. At the step of translation, a G1896A nonsense mutation in the precore region abolishes HBeAg expression. We first reportedthat the G1896A mutation rarely occurred in genotype A. Subsequent studies by others established the role of polymorphism at nucleotide 1858, rather than genotype, as the determinant for the G1896A mutation. Conversion of the precore/core protein to HBeAg requires proteolytic removal of both the amino and carboxy termini, and a (151)RRGR(154) motif has been implicated as the carboxy terminal cleavage site. In this regard, genotype A is unique in possessing a dipeptide insertion that expands the motif into (151)RRDRGR(156). We found that genotype A is cleaved primarily at R156, generating a mature HBeAg that is two amino acids longer than HBeAg from other genotypes. There are different avenues whereby HBeAg expression or its antigenicity can be modulated by viral genotype and naturally occurring mutations.

Changes in viral loads of lamivudine-resistant mutants during entecavir therapy

AIM

Entecavir therapy is effective against lamivudine-resistant virus in patients with hepatitis B virus infection. We investigated viral load changes of YMDD mutant virus (rtM204I [YIDD sequence], rtM204V [YVDD]) in serial serum samples during entecavir treatment for lamivudine-resistant virus and determined changes in viral precore and core promoter mutants.

METHODS

Nineteen patients were treated in randomized, double-blind phase II clinical trials of entecavir at 0.5 or 1.0 mg for breakthrough hepatitis due to lamivudine-resistant virus. Viral changes in YMDD mutants (rtM204I, rtM204V), amino acid changes in the polymerase reverse transcriptase region and precore/core promoter mutations at 52 weeks were determined in 18 patients.

RESULTS

Changes in viral loads of rtM204I and rtM204V were similar. No differences in load changes were seen betweenthe 0.5 and 1.0 mg groups. However, load changes for rtM204I alone were greater than those for the rtM204I + rtM204V mixed-type (P = 0.042, at both 40 and 52 weeks). Load changes in rtM204I and rtM204V with G1896A tended to be greater than those without. Moreover, G1896A was replaced by wild-type virus in two patients at 52 weeks.

CONCLUSION

RtM204I only or the existence of precore mutation was more sensitive to entecavir therapy against lamivudine-resistant virus.