Hepatitis B virus pre-S deletion mutations are a risk factor for hepatocellular carcinoma: a matched nested case-control study

Combined core promoter mutations and pre-S deletion of HBV may not increase the risk of HCC: a geographical epidemiological study in Guangxi, China

BACKGROUND

Although persistent hepatitis B virus (HBV) infection is a major cause of hepatocellular carcinoma (HCC), the mechanisms of oncogenesis remain obscure.

AIMS

To determine whether the findings that HBV basal core promoter (BCP) A1762T, G1764A double mutations, pre-S deletions and a combination of both are risk factors of HCC are supported by geographical epidemiology.

METHODS

Study subjects were recruited from Long An county, where the incidence of HCC is the highest, and five other counties in Guangxi, where the HCC incidence is lower and varies among them. The Pre-S region and BCP of HBV from all study subjects were amplified and sequenced and the data were analysed using chi-squared tests.

RESULTS

The prevalence of BCP and pre-S mutations differs significantly (χ(2) = 9.850, 5.135, respectively, all P < 0.01) between Long An and the other counties. However, the prevalence of combined BCP and pre-S mutations does not differ significantly (χ(2) = 1.510, P > 0.05). These mutations are less frequent in the young but the prevalence of pre-S deletions does not increase with age. The prevalence of these mutations does not differ significantly between men and women but is significantly higher in Zhuang than the other ethnic populations. Among the other five counties, the prevalence of BCP mutations in counties where the HCC incidence is high is significantly higher than that of counties where the HCC incidence is low.

CONCLUSIONS

Combined BCP double mutations and pre-S deletion may not increase the risk of HCC, although these mutations are a risk factor of HCC when they present alone.

Hepatitis B virus genetic variants: biological properties and clinical implications

Hepatitis B virus (HBV) causes a chronic infection in 350 million people worldwide and greatly increases the risk of liver cirrhosis and hepatocellular carcinoma. The majority of chronic HBV carriers live in Asia. HBV can be divided into eight genotypes with unique geographic distributions. Mutations accumulate during chronic infection or in response to external pressure. Because HBV is an RNA-DNA virus the emergence of drug resistance and vaccine escape mutants has become an important clinical and public health concern. Here, we provide an overview of the molecular biology of the HBV life cycle and an evaluation of the changing role of hepatitis B e antigen (HBeAg) at different stages of infection. The impact of viral genotypes and mutations/deletions in the precore, core promoter, preS, and S gene on the establishment of chronic infection, development of fulminant hepatitis and liver cancer is discussed. Because HBV is prone to mutations, the biological properties of drug-resistant and vaccine escape mutants are also explored.

Synergistic effects of A1896, T1653 and T1762/A1764 mutations in genotype c2 hepatitis B virus on development of hepatocellular carcinoma

The effects of genomic changes in hepatitis B virus (HBV) on the occurrence of hepatocellular carcinoma (HCC) are still unclear, especially in relation to the genotype of HBV. In this study, we examined the effects of genomic changes in HBV of genotype C2 on the development of HCC. A total of 318 patients with HBV-associated HCC and 234 patients with chronic hepatitis B (CHB) were studied. All of HCC cases were diagnosed histologically and treated with surgical resection. The whole of the X, S, basal core promoter (BCP) and precore regions of the viral genome from sera or liver tissues were sequenced. All subjects had HBV of genotype C2. The prevalence of the T1653 mutation in the X region and the A1896 mutation in the precore region of HBV was significantly higher in the HCC group than in the control CHB group (22% vs 11%, P = 0.003; 50% vs 23%, P < 0.001, respectively). Moreover, the T1762/A1764 mutations in the BCP region in combination with either T1653 or A1896 were more common in the HCC compared with the CHB group (BCP+X1653: 18% vs 11%, P = 0.05; BCP+PC, 40% vs 15%, P < 0.001, respectively). In multivariate analysis, T1653 and A1896 were revealed to be independent risk factors for HCC development. G1896A in the precore region and C1653T mutation in the X region of genotype C2 HBV are important risk factors for HCC development. Also, the A1762T/G1764A double mutation may act in synergy with C1653T to increase the risk of HCC in patients chronically infected with HBV genotype C2.

Lack of association between hepatitis B virus pre-S mutations and recurrence after surgical resection in hepatocellular carcinoma

Pre-S mutation of hepatitis B virus (HBV) is known to be a risk factor for hepatocarcinogenesis. A previous study suggested that pre-S mutation(s) may associate with increased recurrence after surgical resection. In the present study, 64 patients with HBV-related hepatocellular carcinoma (HCC) were categorized into two groups according to the presence or absence of pre-S mutation(s). The clinicopathological variables of the two groups were analyzed to assess the relationship between pre-S mutations and postoperative recurrence. Nineteen patients (29.7%) had pre-S mutations;13 had a pre-S deletion, three had a pre-S2 start codon mutation, two patients had both a pre-S deletion, and a pre-S2 start codon mutation, and one patient had a pre-S2 insertion. The two groups did not differ in terms of baseline clinicopathological parameters. Cirrhosis and satellite lesion(s) were predictive factors for postoperative recurrence and poor overall survival. Recurrence-free survival (P = 0.320) and overall survival (P = 0.238) did not differ significantly when pre-S mutations were present. In conclusion, this study did not find evidence supporting the notion that pre-S mutation(s) are associated with postoperative recurrence after surgical resection.

Risk stratification for hepatitis B virus related hepatocellular carcinoma

Hepatitis B virus (HBV) infection is the major cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC) worldwide, especially in the Asia-Pacific region. Several hepatitis B viral factors predictive of clinical outcomes in HBV carriers have been identified. The Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer-HBV (REVEAL-HBV) study from Taiwan illustrated the strong association between HBV-DNA level at study entry and risk of HCC over time. In this community-based cohort study, male gender, older age, high serum alanine aminotransferase level, positive hepatitis B e antigen, higher HBV-DNA level, HBV genotype C infection, and core promoter mutation are independently associated with a higher risk of HCC. Another large hospital-based Elucidation of Risk Factors for Disease Control or Advancement in Taiwanese Hepatitis B Carriers cohort of Taiwanese patients further validated the findings of REVEAL-HBV. The risk of HCC started to increase when HBV-DNA level was higher than 2000 IU/mL. Both HBV-DNA and HBsAg levels were shown to be associated with HCC development. While HBV-DNA level had better predictive accuracy than HBsAg level, when investigating the overall cohort in patients with HBV-DNA level < 2000 IU/mL, HBsAg level ≥ 1000 IU/mL was identified as a new independent risk factor for HCC. With the results from REVEAL-HBV, a risk calculation for predicting HCC in non-cirrhotic patients has been developed and validated by independent cohorts (Risk Estimation for Hepatocellular Carcinoma in Chronic Hepatitis B).Taken together, ample evidence indicates that HBsAg level can complement HBV-DNA level in predicting HCC development, especially in HBV carriers with low viral load. In conclusion, HBV treatment guidelines should include the risk stratification of HCC to individualize the management of HBV carriers with different levels of HCC risk.

Hepatitis B virus gene mutations and hepatocarcinogenesis

Chronic hepatitis B virus (HBV) infection has long been the most common cause of hepatocellular carcinoma (HCC). However, some aspects of the pathogenesis of HBV infection and genesis of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) are still inconclusive. An increasing number of published studies indicate that hepatitis B virus mutations are associated with risk of HCC. These variations include, in particular, mutations in ORF S,C,X gene regions. This mini-review summarizes results of clinical studies and molecular mechanisms on the possible relations of HBV mutations with the development of hepatocellular carcinoma.

Whole genome HBV deletion profiles and the accumulation of preS deletion mutant during antiviral treatment

Background

Hepatitis B virus (HBV), because of its error-prone viral polymerase, has a high mutation rate leading to widespread substitutions, deletions, and insertions in the HBV genome. Deletions may significantly change viral biological features complicating the progression of liver diseases. However, the clinical conditions correlating to the accumulation of deleted mutants remain unclear. In this study, we explored HBV deletion patterns and their association with disease status and antiviral treatment by performing whole genome sequencing on samples from 51 hepatitis B patients and by monitoring changes in deletion variants during treatment. Clone sequencing was used to analyze preS regions in another cohort of 52 patients.

Results

Among the core, preS, and basic core promoter (BCP) deletion hotspots, we identified preS to have the highest frequency and the most complex deletion pattern using whole genome sequencing. Further clone sequencing analysis on preS identified 70 deletions which were classified into 4 types, the most common being preS2. Also, in contrast to the core and BCP regions, most preS deletions were in-frame. Most deletions interrupted viral surface epitopes, and are possibly involved in evading immuno-surveillance. Among various clinical factors examined, logistic regression showed that antiviral medication affected the accumulation of deletion mutants (OR = 6.81, 95% CI = 1.296 ~ 35.817, P = 0.023). In chronic carriers of the virus, and individuals with chronic hepatitis, the deletion rate was significantly higher in the antiviral treatment group (Fisher exact test, P = 0.007). Particularly, preS2 deletions were associated with the usage of nucleos(t)ide analog therapy (Fisher exact test, P = 0.023). Dynamic increases in preS1 or preS2 deletions were also observed in quasispecies from samples taken from patients before and after three months of ADV therapy. In vitro experiments demonstrated that preS2 deletions alone were not responsible for antiviral resistance, implying the coordination between wild type and mutant strains during viral survival and disease development.

Conclusions

We present the HBV deletion distribution patterns and preS deletion substructures in viral genomes that are prevalent in northern China. The accumulation of preS deletion mutants during nucleos(t)ide analog therapy may be due to viral escape from host immuno-surveillance.

Correlation between pretreatment viral sequences and the emergence of lamivudine resistance in hepatitis B virus infection

The emergence of amino acid or nucleotide substitutions leads to lamivudine resistance in hepatitis B virus (HBV) infected patients. The aim of this study was to investigate whether viral sequences help predict the emergence of lamivudine resistance. The study subjects comprised 59 consecutive patients infected with HBV treated with daily therapy of 100 mg lamivudine. Among those, 32 patients with adequate pretreatment serum preservation were investigated for the correlation between viral amino acid substitutions and the appearance of lamivudine resistance with consideration of clinical background by determining dominant HBV full open reading frames. Viral resistance to lamivudine emerged in 28 of 59 patients (47%) in a median period of 2.45 years. Sequence comparisons of HBV genomes between patients who later developed lamivudine resistance and patients who did not revealed the existence of significant differences between the two groups in the pre-S1 84 (P = 0.042), pre-S2 1 (P = 0.017) and 22 (P = 0.015), and polymerase tp 95 (P = 0.046), judged by a log-rank test. Viral sequence analyses revealed the presence of amino acid substitutions in HBV pre-S1 and pre-S2 that may be associated with the emergence of lamivudine resistance during chronic HBV infection.

Effects of genomic changes in hepatitis B virus on postoperative recurrence and survival in patients with hepatocellular carcinoma

PURPOSE

To determine whether the genomic changes in hepatitis B virus (HBV) affect the clinical outcomes of hepatocellular carcinoma (HCC) in patients with HBV-associated HCC treated with curative surgical resection.

METHODS

A total of 247 patients with HBV-associated HCC were treated with curative surgical resection. They were followed regularly for a median of 30 months. The whole X, S, basal core promoter (BCP), and precore regions of HBV were sequenced.

RESULTS

The genomic changes such as the G1896A at precore, the A1762T/G1764A at BCP, the C1653T and the T1753V at X gene, and pre-S2 deletion were not significantly associated with postoperative recurrence of HCC or survival of patients after curative resection. However, in univariate analysis, younger age, elevated serum α-fetoprotein level, elevated serum alanine aminotransferase level, larger tumor size, microvascular invasion, and advanced Cancer of the Liver Italian Program stage were closely associated with shorter survival after surgical resection. In multivariate analysis, only microvascular invasion revealed to be an independent risk factor of postoperative recurrence (relative risk [RR] 5.406; P < 0.001); the independent risk factors of shorter survival appeared to be infiltrative type (RR 5.110; P = 0.032), larger tumor size (RR 1.976; P = 0.047), and microvascular invasion (RR 6.118; P < 0.001).

CONCLUSIONS

The postoperative recurrence or survival period may not be affected by the genomic changes at the precore, BCP, X, and pre-S2 regions in HBV of genotype C2 in patients with HBV-associated HCC treated with curative surgical resection. Rather, it may be closely associated with tumor characteristics, such as the size and type of HCC or presence of microvascular invasion.

Hepatitis B virus pre-S2 start codon mutations in Indonesian liver disease patients

AIM: To identify the prevalence of pre-S2 start codon mutations and to assess their association with liver disease progression.

METHODS: The mutations were identified by direct sequencing from 73 asymptomatic carriers, 66 chronic hepatitis (CH), 66 liver cirrhosis (LC) and 63 hepatocellular carcinoma (HCC) patients. Statistical significances were determined using Fisher’s exact test, χ² test, and t-test analyses whenever appropriate. Pre-S mutation as a risk factor for advanced liver disease was estimated by unconditional logistic regression model adjusted with age, sex, and hepatitis B e antigen (HBeAg). P < 0.05 was considered significant.

RESULTS: Mutation of the hepatitis B virus (HBV) pre-S2 start codon was found in 59 samples from 268 subjects (22.0%), with higher prevalence in patients with cirrhosis 27/66 (40.9%) followed by HCC 18/63 (28.6%), chronic hepatitis 12/66 (18.2%) and asymptomatic carriers 2/73 (2.7%) (P < 0.001). Logistic regression analysis showed that pre-S2 start codon mutation was an independent factor for progressive liver disease. Other mutations, at T130, Q132, and A138, were also associated with LC and HCC, although this was not statistically significant when adjusted for age, sex, and HBeAg. The prevalence of pre-S2 start codon mutation was higher in HBV/B than in HBV/C (23.0% vs 19.1%), whilst the prevalence of T130, Q132, and A138 mutation was higher in HBV/C than in HBV/B. The prevalence of pre-S2 start codon mutation was higher in LC (38.9%) and HCC (40.0%) than CH (5.6%) in HBeAg(+) group, but it was similar between CH, LC and HCC in HBeAg(-) group.

CONCLUSION: Pre-S2 start codon mutation was higher in Indonesian patients compared to other Asian countries, and its prevalence was associated with advanced liver disease, particularly in HBeAg(+) patients.

Fine mapping of hepatitis B virus pre-S deletion and its association with hepatocellular carcinoma

BACKGROUND

Naturally occurring pre-S deletion mutants have been identified in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC).

AIMS

This study investigated whether specific deletions within the pre-S region were associated with HCC development.

METHODS

The virologic characteristics of 56 HBV chronic carriers and 112 age-matched patients with HBV-related HCC were examined.

RESULTS

The HCC patients had a significantly higher frequency of high viral load, basal core promoter mutation and pre-S deletion than chronic carriers. Sequencing analysis showed that the deleted regions were clustered mainly in the C terminus of pre-S1 (70.5%) and the N terminus of pre-S2 (72.7%) in HCC patients. Immuno-epitope mapping of these pre-S deletion sequences showed that all the deletion regions encompassed T- and B- cell epitopes and the B-cell epitope at amino acid 1-6 of pre-S2 was significantly deleted in HCC patients (60.0% vs. 0.0%; P = 0.036). Functional mapping of these deletion mutants showed that most of HCC patients lost one or more functional sites and the deletion of site for viral secretion (aa 1-5 of pre-S2 domain) was significantly detected in HCC patients than chronic carriers (62.5% vs. 0.0%; P = 0.029). Computational protein function prediction indicated that these mutants may have different molecular functions and participate in other biological processes compared with wild-type pre-S.

CONCLUSIONS

Deletion of B-cell epitope at amino acid 1-6 of pre-S2 region and the site for virion secretion are significantly associated with the development of HCC in HBV carriers.

Impact of hepatitis B virus (HBV) preS/S genomic variability on HBV surface antigen and HBV DNA serum levels

To evaluate whether hepatitis B virus (HBV) preS/S gene variability has any impact on serum hepatitis B surface antigen (HBsAg) levels and to analyze the replication capacity of naturally occurring preS/S variants, sera from 40 untreated patients with HBV-related chronic liver disease (hepatitis B e antigen [HBeAg]-positive, n = 11; HBeAg-negative, n = 29) were virologically characterized. Additionally, phenotypic analysis of three different preS/S variant isolates (carrying a 183-nucleotide deletion within the preS1 region, the deletion of preS2 start codon, and a stop signal at codon 182 within the S gene, respectively) was performed. HBV infecting 14 (35%) patients had single or multiple preS/S genomic mutations (i.e., preS1 and/or preS2 deletions, preS2 start codon mutations, C-terminally truncated and/or "a" determinant mutated S protein). Presence of preS/S variants negatively correlated with HBsAg titers (r = -0.431; P = 0.005) and its prevalence did not significantly differ between HBeAg-positive and HBeAg-negative patients. No correlation was found between HBsAg and HBV DNA levels in patients infected with preS/S mutants, whereas a significant correlation was found between HBsAg and viremia levels (r = 0.607; P = 0.001) in patients infected with wild-type HBV strains. HepG2 cells replicating the above-mentioned three preS/S variants showed significant reduction of HBsAg secretion, retention of envelope proteins in the endoplasmic reticulum, less efficient virion secretion and nuclear accumulation of significantly higher amounts of covalently closed circular DNA compared with wild-type HBV replicating cells.

CONCLUSION

In patients infected with preS/S variants, HBV DNA replication and HBsAg synthesis/secretion appear to be dissociated. Therefore, the use of HBsAg titer as diagnostic/prognostic tool has to take into account the frequent emergence of preS/S variants in chronic HBV infection.

Tracking the naturally occurring mutations across the full-length genome of hepatitis B virus of genotype D in different phases of chronic e-antigen-negative infection

Hepatitis B e-antigen (HBeAg)-negative chronic HBV infection is highly prevalent in several parts of the world, including India, with the clinical spectrum ranging from inactive carrier (IC) state to chronic 'e-negative' hepatitis B (CHB) and culminating in advanced liver disease such as cirrhosis (LC). The present study has for the first time investigated the natural diversity of HBV belonging to genotype D in treatment-naïve Indian patients representing the above phases of HBeAg-negative infection to identify candidate mutations associated with each disease state. Studies of full-length HBV/D sequences revealed that the progressive accumulation and persistence of mutations in basal core promoter, negative regulatory element, Pre-core region, the B- and T-cell epitopes of X protein as well as deletions in the PreS region contribute significantly to disease progression from IC through CHB to LC. In addition, the development of CHB was associated with a significant increase in viral variants characterized by mutations in enhancer II, preS1 promoter, T-cell epitope of core and B-cell epitope region of PreS1. While few of the mutations were previously reported in the context of HBV genotypes B and C, others had not been documented before. Our results thus highlight a distinct pattern of mutation in HBV/D that may help in predicting clinical outcomes of HBeAg-negative infection and have implications for better clinical management of the patients.

Functional analysis of hepatitis B virus pre-s deletion variants associated with hepatocellular carcinoma

BACKGROUND

Naturally occurring pre-S deletion mutants have been identified in hepatitis B carriers and shown to be associated with the development of hepatocellular carcinoma. The phenotypes of these pre-S deletion genomes remain unclear, and they were investigated in this study.

METHODS

The pre-S deletion genomes: (1) pre-S1 deletion, (2) deletion spanning pre-S1 and pre-S2, (3) pre-S2 N-terminal deletion, and (4) pre-S2 internal deletion were constructed and analyzed by transfection into Huh-7 cells.

RESULTS

Functional analyses reveal that these mutants were divided into two groups: S promoter deletion and non-S promoter deletion variants. Compared with the wild-type genome, S promoter deletion variants led to an inverse ratio of pre-S1 mRNA and pre-S2/S mRNA, and intracellular accumulation of surface proteins. An interesting finding is that a small amount of L proteins was detected in the medium from S promoter deletion variant-transfected cells. Non-S promoter deletion variants conversely displayed a wild-type like mRNA and protein pattern. The secretion of surface proteins from non-S promoter deletion variants was inhibited less than from S promoter deletion variant. Immunofluorescence analysis showed mutant surface proteins colocalized with ER and exhibited an atypical distribution: granular staining pattern in the S-promoter deletion variants and perinuclear staining pattern in the non-S promoter deletion variants.

CONCLUSION

This study shows that these pre-S deletion genomes exhibit two different phenotypes in mRNA transcription, surface protein expression and secretion. This diversity seems to result from the deletion of S promoter rather than result from the deletion of pre-S1 or pre-S2.

Low prevalence of hepatitis B virus pre-S deletion mutation in Indonesia

The molecular epidemiological study of hepatitis B virus (HBV) in Indonesia is still limited. This study was aimed to identify the prevalence of HBV pre-S deletion/insertion mutations, and to assess the association of pre-S deletion mutation with liver disease progression in Indonesia. Pre-S mutations were identified by direct sequencing. Of the 265 subjects, 32 samples (12.1%) harbored pre-S deletion/insertion mutations. The prevalence of those pre-S mutations was 2.7% (2/75), 12.9% (8/62), 16.7% (11/66), and 17.7% (11/62) in asymptomatic carrier, chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma groups, respectively. Statistical analysis showed significant difference among them (P = 0.024). In HBV genotype B (HBV/B), pre-S1, pre-S1/S2, and pre-S2 deletion mutations were detected respectively in 3 (17.6%), 4 (23.5%), and 9 (52.9%) of 17 samples. On the other hand, in HBV/C, 12 of 15 samples (80.0%) showed a pre-S2 deletion mutation, and only 2 samples (13.3%) demonstrated a pre-S1/S2 deletion mutation. These results suggest that in HBV/B deletion mutation tends to occur in pre-S1 or pre-S1/S2 region, while in HBV/C the deletion mutation usually occurs in the pre-S2 region. Analysis of complete genome of four viruses confirmed that 3 isolates were classified into HBV/B3, and 1 isolate was HBV/C1. However, SimPlot and BootScan analyses showed that isolate 08.10.002 was an intragenotypic recombinant between HBV/B3 and HBV/B4. As conclusion, the prevalence of HBV pre-S mutations was relatively low in Indonesian patients compared to those from Taiwan, Japan, and other Asian countries. There was a weak association between pre-S deletion mutation and progressive liver disease.

Hepatitis B virus infection and the risk of hepatocellular carcinoma

Epidemiological studies have provided overwhelming evidence for a causal role of chronic hepatitis B virus (HBV) infection in the development of hepatocellular carcinoma (HCC). However, the pathogenesis of HBV infection and carcinogenesis of HBV-associated HCC are still elusive. This review will summarize the current knowledge on the mechanisms involved in HBV-related liver carcinogenesis. The role of HBV in tumor formation appears to be complex, and may involve both direct and indirect mechanisms. Integration of HBV DNA into the host genome occurs at early steps of clonal tumor expansion, and it has been shown to enhance the host chromosomal instability, leading to large inverted duplications, deletions and chromosomal translocations. It has been shown that the rate of chromosomal alterations is increased significantly in HBV-related tumors. Prolonged expression of the viral regulatory HBV x protein may contribute to regulating cellular transcription, protein degradation, proliferation, and apoptotic signaling pathways, and it plays a critical role in the development of hepatocellular carcinoma.

A ubiquitin independent degradation pathway utilized by a hepatitis B virus envelope protein to limit antigen presentation

Hepatitis B virus envelope glycoproteins Large (L), Middle (M) and Small (S) are targets of the host cellular immune system. The extent to which the host recognizes viral antigens presented by infected cells is believed to play a decisive role in determining if an infection will be resolved or become chronic. As with other antigens, HBV envelope polypeptides must be degraded, presumably by cellular proteasomes, to be presented by the MHC I pathway. We have used M as a model to study this process and determine how ER quality control monitors these foreign polymeric proteins and disposes of them through the ER-associated degradation (ERAD) pathway. Using both wild type and mutant HBV M protein, we found that unlike most ERAD substrates, which require ubiquitination for retrotranslocation and degradation, the HBV M protein, which only contains two lysine residues, can undergo rapid and complete, ubiquitin independent, proteasome dependent degradation. The utilization of this pathway had a functional consequence, since proteins degraded through it, were poorly presented via MHC I. To test the hypothesis that the level of ubiquitination, independent of protein degradation, controls the level of antigen presentation, we inserted two additional lysines into both the wild type and mutant M protein. Amazingly, while the addition of the lysine residues dramatically increased the level of ubiquitination, it did not alter the rate of degradation. However and remarkably, the increased ubiquitination was associated with a dramatic increase in the level of antigen presentation. In conclusion, using the HBV surface protein as a model, we have identified a novel ubiquitin independent degradation pathway and determined that this pathway can have implications for antigen presentation and potentially viral pathogenesis.

Distinct mutant hepatitis B virus genomes, with alterations in all four open reading frames, in a single South African hepatocellular carcinoma patient

Sequence variation of hepatitis B virus (HBV) can influence the replication, antigen expression and pathogenicity of the virus. We report on the mutational analysis of HBV performed in a 28-year-old Black South African female diagnosed with HBV-induced hepatocellular carcinoma. Full-genome amplification and DNA sequencing of HBV was carried out. Five distinct complete genomic clones were described with extensive genomic and intragenic variation. Phylogenetic analysis revealed that all five clones belonged to subgenotype A1 and that there were at least four virus populations with genomes of different lengths ranging from 3194 to 3253 base pairs. In this particular patient, four major characteristic features, not previously reported to occur simultaneously in HBV isolated from a single patient, were observed. Firstly, all the clones harboured a 13 base pair deletion and a 45 base pair insertion in the basic core promoter (BCP). Secondly, a 37 base pair insertion in the core gene with three adjacent single nucleotide deletions were observed. Thirdly, premature S gene stop codons were observed in some clones and lastly X gene initiation codon mutations were also observed. The complex nature of the mutations in the HBV isolated from this single patient may have contributed to the early onset of hepatocarcinogenesis.

HBV vaccine efficacy and detection and genotyping of vaccineé asymptomatic breakthrough HBV infection in Egypt

AIM

To evaluate the impact of mass vaccination against the hepatitis B virus (HBV) in Egypt, and to search for vaccinee asymptomatic breakthrough HBV infection and its genotype.

METHODS

Seven hundred serum samples from vaccinated children and adults (aged 2-47 years) were used for quantitative and qualitative detection of HBsAb by ELISA. Three hundred and sixty serum samples representing undetectable or low or high HBsAb were screened for markers of active HBV infection (HBsAg, HBcAb (IgG) and HBeAb by ELISA, plus HBsAg by AxSYM) and HBV-DNA genotyping by nested multiplex PCR and by DNA sequencing.

RESULTS

It was found that 65% of children aged 2-4 years, and 20.5% aged 4-13 years, as well as 45% adults were good responders to HBV vaccination mounting protective level HBsAb. Poor responders were 28%, 59.5% and 34%, and non-responders were 7%, 20% and 21% respectively, in the three studied groups. Markers of asymptomatic HBV infections were HBsAg detected by ELISA in 2.5% vs 11.39% by AxSYM. Other markers were HBcAb (IgG) in 1.38%, HBeAb in 0.83%, and HBV-DNA in 7.8%. All had HBV genotype E infection.

CONCLUSION

It is concluded that HBV vaccine is efficient in controlling HBV infection among children and adults. The vaccine breakthrough infection was by HBV genotype E. A booster dose of vaccine is recommended, probably four years after initial vaccination.

Genotypes, mutations, and viral load of hepatitis B virus and the risk of hepatocellular carcinoma: HBV properties and hepatocarcinogenesis

Chronic infection with hepatitis B virus (HBV) is the major risk factor for hepatocellular carcinoma (HCC) worldwide. Ten HBV genotypes (A-J) have been discovered so far. Genotypes B and C are endemic in East and Southeast Asia. Genotype C HBV is associated with increased risks of cirrhosis and HCC. Genotype B (B2) is associated with the development of HCC in non-cirrhotic patients younger than 50 years and with relapse of HCC after surgical treatment. It is also associated with earlier hepatitis B e antigen seroconversion than genotype C. High HBV load is independently associated with the occurrence and post-treatment recurrence of HCC. Different genotypes have distinct patterns of mutations. Viral mutations in the core promoter region and in the preS region are frequently found to be significantly associated with an increased risk of HCC. These mutations often occur before the onset of HCC and accumulate during the progression of chronic HBV infection. Multiple such mutations are more frequent in patients with HCC and are specific for HCC. HBV subgenotypes, viral mutations, and viral load can be used for the prediction of HCC. Early identification of HBV-infected individuals who will eventually develop HCC will help to develop active prophylactic protocols to reduce or delay the occurrence of HCC.

Profile of pre-S deletions in the natural history of chronic hepatitis B infection

It have been suggested that hepatitis B virus (HBV) pre-S deletions may play a role in hepatocarcinogenesis. The aim of the study was to determine the prevalence of pre-S deletions in chronic hepatitis B patients in Hong Kong, the factors associated with the deletions and its relationship with hepatitis B e antigen (HBeAg) seroconversion. HBV pre-S deletions were determined by nucleotide sequence analysis in 178 patients with chronic HBV (cross-sectional study). Eighty-four patients had paired samples before and after HBeAg seroconversion (longitudinal study). The prevalence of pre-S deletions was 12.9% (23/178). A majority of the pre-S deletions (73.9%) occurred in the 5' terminus of pre-S2 region whereas deletions in the pre-S1 region appeared less frequently (47.8%). There was no relationship between age and pre-S deletions. Male gender [odds ratio (OR) =10.88; 95% confidence interval (CI) =1.37-86.52; P=0.024] and HBV genotype C (OR=13.85; 95% CI=3.05-62.92; P=0.001) were independent factors associated with pre-S deletions. Only 17 out of the 84 patients with paired samples before and after HBeAg seroconversion had pre-S deletions. The patterns of pre-S deletions before and after HBeAg seroconversion were variable. Compared with genotype B, HBV genotype C was associated with earlier emergence of pre-S deletions. In conclusion, 12.9% of chronic HBV carriers had pre-S deletions (predominantly pre-S2 deletions) in a geographical area highly endemic for chronic hepatitis B. Male gender and HBV genotype C were associated independently with the development of pre-S deletion mutations. There was no clear relationship between HBeAg seroconversion and pre-S deletions.

Association of hepatitis B virus pre-S deletions with the development of hepatocellular carcinoma in chronic hepatitis B

BACKGROUND

We aimed to determine whether hepatitis B virus (HBV) pre-S deletion was an independent factor for the development of hepatocellular carcinoma (HCC).

METHODS

Pre-S deletions were determined in HBV isolates from 115 chronic hepatitis B (CHB) patients with HCC. Sixty-nine patients were further matched with 69 CHB patients without HCC for age, sex, hepatitis B e antigen (HBeAg) status, and HBV genotype.

RESULTS

HBV pre-S deletions were clustered mainly in the 3' end of pre-S1 and 5' end of pre-S2 regions. Adjusted for confounding risk factors, patients with HCC had a higher prevalence of HBV with pre-S deletions than did patients without HCC (23 [33.3%] of 69 vs 11 [15.9%] of 69; P = .018; odds ratio [OR], 2.64). In particular, only pre-S2 deletions but not pre-S1 deletions were significantly associated with the development of HCC (P = .020). A higher prevalence of pre-S deletions was observed in HBV isolates from HCC patients under the age of 50 years than from those older than 50 years (10 [62.5%] of 16 vs 13 [24.5%] of 53; P = .012; OR, 5.13). Emergence of de novo pre-S deletions was documented before the development of HCC.

CONCLUSIONS

HBV pre-S2 deletions were an independent factor associated with the development of HCC. Its oncogenic role may be more important in young patients with HCC.

Management of hepatitis B: Consensus of the Japan Society of Hepatology 2009

Recently, much progress has been made in the field of hepatitis B, such as natural history of the disease in relation to the amount of hepatitis B virus (HBV) DNA, genotypes of HBV influencing the natural course and treatment effects, mutations of HBV influencing the severity of the disease and development of hepatocellular carcinoma, and antiviral treatment such as nucleos(t)ide analogues and pegylated interferon. To make the consensus for the diagnosis, management and treatment of hepatitis B, a meeting was held during 45th annual meeting of Japan Society of Hepatology (JSH) in June 2009. In the meeting, recommendations and informative statements were discussed on the following subjects: (i) natural history of HBV infection; (ii) clinical implication of HBV genotypes; (iii) HBV mutations and their potential impact on pathogenesis of HBV infection; (iv) indications for antiviral treatment of chronic hepatitis B; (v) nucleos(t)ide analogues for chronic hepatitis B; and (vi) interferon therapy for chronic hepatitis B. The presenters reviewed the data on these subjects and proposed the consensus statements and recommendations. These statements were discussed among the organizers and presenters, and were approved by the participants of the meeting. In the current report, the relevant data were reviewed and the 12 consensus statements and nine recommendations on chronic hepatitis B were described.

A complex hepatitis B virus (X/C) recombinant is common in Long An county, Guangxi and may have originated in southern China

Recently, a complex (X/C) hepatitis B virus (HBV) recombinant, first reported in 2000, was proposed as a new genotype; although this was refuted immediately because the strains differ by less than 8 % in nucleotide distance from genotype C. Over 13.5 % (38/281) of HBV isolates from the Long An cohort in China were not assigned to a specific genotype, using current genotyping tools to analyse surface ORF sequences, and these have about 98 % similarity to the X/C recombinants. To determine whether this close identity extends to the full-length sequences and to investigate the evolutionary history of the Long An X/C recombinants, 17 complete genome sequences were determined. They are highly similar (96–99 %) to the Vietnamese strains and, although some reach or exceed 8 % nucleotide sequence difference from all known genotypes, they cluster together in the same clade, separating in a phylogenetic tree from the genotype C branch. Analysis of recombination reveals that all but one of the Long An isolates resembles the Vietnamese isolates in that they result from apparent recombination between genotype C and a parent of unknown genotype (X), which shows similarity in part to genotype G. The exception, isolate QL523, has a greater proportion of genotype C parent. Phylogeographic analysis reveals that these recombinants probably arose in southern China and spread later to Vietnam and Laos.

Significant association of different preS mutations with hepatitis B-related cirrhosis or hepatocellular carcinoma

BACKGROUND

The associations of nucleotide substitution mutations in the preS region of hepatitis B virus (HBV) with hepatocellular carcinoma (HCC) and cirrhosis remain unknown. We aimed to determine the associations of preS mutations with HCC or cirrhosis.

METHODS

HBV from 603 asymptomatic hepatitis B surface antigen carriers (ASCs), 219 chronic hepatitis B (CHB) patients, 119 cirrhosis patients, and 231 HCC patients were genotyped and sequenced in the preS region. Nucleotides with the highest frequencies in HBV from the hepatitis B e antigen (HBeAg)-positive ASCs were treated as "wild-type" nucleotides. Twenty-one preS1 mutations and 14 preS2 mutations were evaluated. Multivariate regression analyses were applied to determine factors independently associated with cirrhosis or HCC.

RESULTS

Most (85.7%) preS2 mutations were associated with CHB compared with ASCs, whereas most preS1 mutations were associated with HCC compared with the cirrhosis patients or CHB patients. Compared with the CHB patients, 81.0% preS1 mutations in genotype C were inversely associated with cirrhosis. Multivariate regression analyses showed that C2964A, C3116T, and C7A were novel factors associated with HCC compared with those without HCC, whereas A2964C and T3116C were independently associated with cirrhosis compared with ASCs and the CHB patients. Combined preS1 mutations had specificities greater than 95%, while C3116T and C7A had moderate sensitivities and specificities, for HCC.

CONCLUSIONS

C2964A, C3116T, and C7A are novel markers independently associated with an increased risk of HCC, while A2964C and T3116C are novel markers independently associated with an increased risk of cirrhosis. Combined preS1 mutations are specific for HCC.

HBV mutations in untreated HIV-HBV co-infection using genomic length sequencing

HIV infection has a significant impact on the natural progression of hepatitis B virus (HBV) related liver disease. In HIV-HBV co-infected patients, little is known about mutations in the HBV genome, which can influence severity of liver disease. The aim of this study was to characterize and to determine the frequency of known clinically significant mutations in the HBV genomes from HIV-HBV co-infected patients and from HBV mono-infected patients. To accomplish this, genomic length HBV sequencing was performed in highly-active anti-retroviral therapy (HAART)-naïve HIV-HBV co-infected patients (n=74) and in anti-HBV therapy-naïve HBV mono-infected patients (n=55). The frequency of HBV mutations differed between the co-infected and mono-infected patients when comparing patients with the same genotype. BCP mutations A1762T and G1764A were significantly more frequent in HBV genotype C mono-infection and the -1G frameshift was significantly more frequent in co-infection and was only observed in HBV genotype A co-infection. PreS2 deletions were observed more frequently in the setting of co-infection. Further work is needed to determine if these mutational patterns influence the differences in liver disease progression in HIV-HBV co-infected and HBV mono-infected patients.

Chronic hepatitis B: whom to treat and for how long? Propositions, challenges, and future directions

Recent guidelines of the American Association for the Study of Liver Diseases, the European Association for the Study of the Liver, and the Asian Pacific Association for the Study of the Liver 2008 update of the "Asian-Pacific consensus statement on the management of chronic hepatitis B" offer comprehensive recommendations for the general management of chronic hepatitis B (CHB). These recommendations highlight preferred approaches to the prevention, diagnosis, and treatment of CHB. Nonetheless, the results of recent studies have led to an improved understanding of the disease and a belief that current recommendations on specific therapeutic considerations, including CHB treatment initiation and cessation criteria, particularly in patient populations with special circumstances, can be improved. Twelve experts from the Asia-Pacific region formed the Asia-Pacific Panel Recommendations for the Optimal Management of Chronic Hepatitis B (APPROACH) Working Group to review, challenge, and assess relevant new data and inform future updates of CHB treatment guidelines. The significance of and controversy about reported findings were discussed and debated in an expert meeting of the Working Group in Beijing, China, in November 2008. This review paper attempts to identify areas requiring improved CHB management and provide suggestions for future guideline updates, with special emphasis on treatment initiation and duration.

Pre-S2 deletions of hepatitis B virus and hepatocellular carcinoma in children

The cause of early oncogenesis in hepatitis B virus (HBV)-related childhood hepatocellular carcinoma (HCC) remains unclear. This study investigated whether pre-S deletion of HBV is related to childhood HCC. By using nested polymerase chain reaction, we compared the pre-S sequence of HBV from sera of children with HCC against control children with similar chronic HBV infection. The HBV in sera of children with HCC had a significantly higher rate of pre-S deletion than that of children with chronic HBV infection (p = 0.008). All except one of the pre-S deletions from the HCC group involved the pre-S2 region, whereas no pre-S2 deletion was found in the chronic HBV group (p = 0.003). There was a trend whereby genotype-C sera had a higher rate of pre-S2 deletion than genotype-B sera (p = 0.11). A multivariate logistic regression model revealed that pre-S deletion was an independent risk factor for HCC in children (odds ratio: 36.69, p = 0.015). In conclusion, pre-S2 deletion does not need to take decades to occur; its presence in nearly half of children with HCC, in contrast to its absence in children with chronic HBV infection, suggests a link between pre-S2 deletion and HCC development in children.

Worldwide genetic diversity of HBV genotypes and risk of hepatocellular carcinoma

Hepatitis B viruses (HBV) are responsible for over 50% of the worldwide attributable risk of hepatocellular carcinoma (HCC) and this figure increases even further in regions of high endemicity. Systematic sequencing of HBV genomes has identified that this common virus existed as eight distinct genotypes (denoted A-H), each regrouping variants with less than 8% divergence in their DNA sequence. These genotypes differ by their geographic distribution in populations around the globe. There is evidence that HBV genotypes also differ by their pathogenic properties, including their risk of persistence as chronic infection and their capacity to induce precursor disease or cancer. On the other hand, HBV genes may undergo mutations that become selected during the course of chronic infection and progressive liver disease. The most significant of these mutations in the context of HCC are those occurring in the pre-core (Pre-C) and basal core promoter (BCP) regions. These mutations may upregulate HBV expression and increase its virulence. These mutations may occur in all HBV genotypes but are more common in genotypes associated with more severe disease and cancer, in particular genotype C. Understanding the molecular basis of pathological variations between HBV variants is critical for prediction of disease severity. It will also be important to determine whether differences among genotypes may have an impact on the long-term protective efficacy of universal HBV vaccination.

Association of concurrent hepatitis B surface antigen and antibody to hepatitis B surface antigen with hepatocellular carcinoma in chronic hepatitis B virus infection

Antibody to hepatitis B surface antigen (HBsAg) (anti-HBs) can exist in patients with chronic hepatitis B virus (HBV) infection. To date, little is known about the association of concurrent HBsAg and anti-HBs (concurrent HBsAg/ anti-HBs) with hepatocellular carcinoma (HCC). The aim of this study was to investigate the clinical relevance of concurrent HBsAg/anti-HBs with preS deletion mutations and HCC in chronic HBV infection. A total of 755 patients with chronic HBV infection were included consecutively at a tertiary center. Logistic regression analysis was used to identify risk factors for HCC, and serum HBV DNA was amplified, followed by direct sequencing to detect preS deletions. The prevalence of concurrent HBsAg/anti-HBs was 6.4% (48/755) and all HBVs tested were genotype C. HCC occurred more frequently in the concurrent HBsAg/anti-HBs group than in the HBsAg only group [22.9% (11/48) vs. 7.9% (56/707), P = 0.002]. In multivariate analyses, age >40 years [odds ratio (OR), 14.712; 95% confidence interval (CI), 4.365-49.579; P < 0.001], male gender (OR 2.431; 95% CI, 1.226-4.820; P = 0.011), decompensated cirrhosis (OR, 3.642; 95% CI, 1.788-7.421; P < 0.001) and concurrent HBsAg/anti-HBs (OR, 4.336; 95% CI, 1.956-9.613; P < 0.001) were associated independently with HCC. In molecular analysis, preS deletion mutations were more frequent in the concurrent HBsAg/anti-HBs and HCC groups than in the HBsAg without HCC group (42.3% and 32.5% vs. 11.3%; P = 0.002 and 0.012, respectively). In conclusion, concurrent HBsAg/anti-HBs is associated with preS deletion mutations and may be one of the risk factors for HCC in chronic HBV infection with genotype C.

A pre-S gene chip to detect pre-S deletions in hepatitis B virus large surface antigen as a predictive marker for hepatoma risk in chronic hepatitis B virus carriers

BACKGROUND

Chronic hepatitis B virus (HBV) infection is an important cause of hepatocellular carcinoma (HCC) worldwide. The pre-S1 and -S2 mutant large HBV surface antigen (LHBS), in which the pre-S1 and -S2 regions of the LHBS gene are partially deleted, are highly associated with HBV-related HCC.

METHODS

The pre-S region of the LHBS gene in two hundred and one HBV-positive serum samples was PCR-amplified and sequenced. A pre-S oligonucleotide gene chip was developed to efficiently detect pre-S deletions in chronic HBV carriers. Twenty serum samples from chronic HBV carriers were analyzed using the chip.

RESULTS

The pre-S deletion rates were relatively low (7%) in the sera of patients with acute HBV infection. They gradually increased in periods of persistent HBV infection: pre-S mutation rates were 37% in chronic HBV carriers, and as high as 60% in HCC patients. The Pre-S Gene Chip offers a highly sensitive and specific method for pre-S deletion detection and is less expensive and more efficient (turnaround time 3 days) than DNA sequencing analysis.

CONCLUSION

The pre-S1/2 mutants may emerge during the long-term persistence of the HBV genome in carriers and facilitate HCC development. Combined detection of pre-S mutations, other markers of HBV replication, and viral titers, offers a reliable predictive method for HCC risks in chronic HBV carriers.

Drastic reduction in the production of subviral particles does not impair hepatitis B virus virion secretion

Hepatitis B virus (HBV) contains three coterminal envelope proteins on the virion surface: large (L), middle (M), and small (S). The M and S proteins are also secreted as empty "subviral particles," which exceed virions by at least 1,000-fold. The S protein serves as the morphogenic factor for both types of particles, while the L protein is required only for virion formation. We found that cotransfecting replication constructs with a small dose of the expression construct for the missing L, M, and S proteins reconstituted efficient virion secretion but only 5 to 10% of subviral particles. The L protein inhibited secretion of subviral particles in a dose-dependent manner, whereas a too-high or too-low L/S protein ratio inhibited virion secretion. Consistent with the results of cotransfection experiments, a point mutation at the -3 position of the S gene AUG codon reduced HBsAg secretion by 60 to 70% but maintained efficient virion secretion. Surprisingly, ablating M protein expression reduced virion secretion but markedly increased the maturity of virion-associated genomes, which could be reversed by providing in trans both L and M proteins but not just M protein. M protein stability was dependent on the coexpression of S protein. Our findings suggest that efficient HBV virion secretion could be maintained despite drastic reduction in subviral particle production, which supports the recent demonstration of separate secretion pathways adopted by the two types of particles. The M protein appears to facilitate core particle envelopment, thus shortening the window of plus strand DNA elongation.