Combinations of eight key mutations in the X/preC region and genomic activity of hepatitis B virus are associated with hepatocellular carcinoma

Evolution and diversity of the hepatitis B virus genome: Clinical implications

Hepatitis B virus (HBV) infection remains a significant global health burden. The genetic variation of HBV is complex. HBV can be divided into nine genotypes, which show significant differences in geographical distribution, clinical manifestations, transmission routes and treatment response. In recent years, substantial progress has been made through various research methods in understanding the development, pathogenesis, and antiviral treatment response of clinical disease associated with HBV genetic variants. This progress provides important theoretical support for a deeper understanding of the natural history of HBV infection, virus detection, drug treatment, vaccine development, mother-to-child transmission, and surveillance management. This review summarizes the mechanisms of HBV diversity, discusses methods used to detect viral diversity in current studies, and the impact of viral genome variation during infection on the development of clinical disease.

The A1762T/G1764A mutations enhance HBV replication by alternating viral transcriptome

The A1762T/G1764A mutations, one of the most common mutations in the hepatitis B virus basal core promoter, are associated with the progression of chronic HBV infection. However, effects of these mutations on HBV replication remains controversial. This study aimed to systematically investigate the effect of the mutations on HBV replication and its underlying mechanisms. Using the prcccDNA/pCMV-Cre recombinant plasmid system, a prcccDNA-A1762T/G1764A mutant plasmid was constructed. Compared with wild-type HBV, A1762T/G1764A mutant HBV showed enhanced replication ability with higher secreted HBV DNA and RNA levels, while Southern and Northern blot indicated higher intracellular levels of relaxed circular DNA, single-stranded DNA, and 3.5 kb RNA. Meanwhile, the mutations increased expression of intracellular core protein and decreased the production of HBeAg and HBsAg. In vitro infection based on HepG2-NTCP cells and mice hydrodynamic injection experiment also proved that these mutations promote HBV replication. 5'-RACE assays showed that these mutations upregulated transcription of pregenomic RNA (pgRNA) while downregulating that of preC RNA, which was further confirmed by full-length transcriptome sequencing. Moreover, a proportion of sub-pgRNAs with the potential to express polymerase were also upregulated by these mutations. The ChIP-qPCR assay showed that A1762T/G1764A mutations created a functional HNF1α binding site in the BCP region, and its overexpression enhanced the effect of A1762T/G1764A mutations on HBV. Our findings revealed the mechanism and importance of A1762T/G1764A mutations as an indicator for management of CHB patients, and provided HNF1α as a new target for curing HBV-infected patients.

Low host immune pressure may be associated with the development of hepatocellular carcinoma: a longitudinal analysis of complete genomes of the HBV 1762T, 1764A mutant

Background

It has been reported that hepatitis B virus (HBV) double mutations (A1762T, G1764A) are an aetiological factor of hepatocellular carcinoma (HCC). However, it is unclear who is prone to develop HCC, among those infected with the mutant. Exploring HBV quasispecies, which are strongly influenced by host immune pressure, may provide more information about the association of viral factors and HCC.

Materials and methods

Nine HCC cases and 10 controls were selected from the Long An cohort. Serum samples were collected in 2004 and 2019 from subjects with HBV double mutations and the complete genome of HBV was amplified and sequenced using next-generation sequencing (NGS).

Results

The Shannon entropy values increased from 2004 to 2019 in most cases and controls. There was no significant difference in mean intrahost quasispecies genetic distances between cases and controls. The change in the values of mean intrahost quasispecies genetic distances of the controls between 2004 and 2019 was significantly higher than that of the cases (P<0.05). The viral loads did not differ significantly between cases and controls in 2004(p=0.086) but differed at diagnosed in 2019 (p=0.009). Three mutations occurring with increasing frequency from 2004 to 2019 were identified in the HCC cases, including nt446 C→G, nt514 A→C and nt2857T→C. Their frequency differed significantly between the cases and controls (P<0.05).

Conclusions

The change in the values of mean intrahost quasispecies genetic distances in HCC was smaller, suggesting that HBV in HCC cases may be subject to low host immune pressure. Increasing viral loads during long-term infection are associated with the development of HCC. The novel mutations may increase the risk for HCC.

Cellular Factors Involved in the Hepatitis D Virus Life Cycle

Hepatitis D virus (HDV) is a defective RNA virus with a negative-strand RNA genome encompassing less than 1700 nucleotides. The HDV genome encodes only for one protein, the hepatitis delta antigen (HDAg), which exists in two forms acting as nucleoproteins. HDV depends on the envelope proteins of the hepatitis B virus as a helper virus for packaging its ribonucleoprotein complex (RNP). HDV is considered the causative agent for the most severe form of viral hepatitis leading to liver fibrosis/cirrhosis and hepatocellular carcinoma. Many steps of the life cycle of HDV are still enigmatic. This review gives an overview of the complete life cycle of HDV and identifies gaps in knowledge. The focus is on the description of cellular factors being involved in the life cycle of HDV and the deregulation of cellular pathways by HDV with respect to their relevance for viral replication, morphogenesis and HDV-associated pathogenesis. Moreover, recent progress in antiviral strategies targeting cellular structures is summarized in this article.

Anti-rheumatic drug-induced hepatitis B virus reactivation and preventive strategies for hepatocellular carcinoma

To date, an estimated 3 million people worldwide have been infected with chronic hepatitis B virus (HBV). Although anti-HBV therapies have improved the long-term survival profile of chronic carriers, viral reactivation still poses a significant challenge for preventing HBV-related hepatitis, hepatocellular carcinoma (HCC), and death. Immuno-modulating drugs, which are widely applied in managing rheumatic conditions, are commonly associated with HBV reactivation (HBVr) as a result of drug-induced immune suppression. However, there are few reports on the risk of HBVr and the medication management plan for HBV carriers, especially rheumatic patients. In this review, we summarize immuno-modulating drug-induced HBVr during rheumatoid therapy and its preventive strategies for HBVr-induced liver diseases, especially cirrhosis and HCC. These findings will assist with developing treatments for rheumatic patients, and prevent HBV-related cirrhosis and HCC.

Novel X gene point mutations in chronic hepatitis B and HBV related cirrhotic patients

INTRODUCTION

HBx is a multifunctional modulator viral protein with key roles in various biological processes such as signal transduction, transcription, proliferation, and cell apoptosis. Also, HBx has an important role in the progression of cirrhosis and hepatocellular carcinoma (HCC). This study aimed to determine mutations in X gene, enhancer II (EnhII), and basal core promoter (BCP) of genotype D of Hepatitis B Virus (HBV) in cirrhotic and chronic HBV patients.

MATERIAL AND METHODS

This cross-sectional study was performed on 68 cases with chronic HBV (cHBV) and 50 cases with HBV related cirrhosis. Serum samples were obtained for genomic DNA extraction. Semi-nested PCR was used to amplify the HBx region. Point mutations in the HBx region were detected by sequencing.

RESULT

Novel mutations were detected, including C1491G, C1500T, G1613T, and G1658T in the N-terminal of the X gene. The frequency of C1481T/G1479A, T1498C, C1500T, G1512A, A1635T, C1678T, A1727T, and A1762T/ G1764A/ C1773T was significantly higher in cirrhotic patients compared to chronically HBV infected ones. A higher rate of A1635T, C1678T, A1727T, A1762T, G1764A, and C1773T was observed in cirrhotic patients.

CONCLUSION

Our findings showed that the frequency of mutations in the basal-core promoter, enhancer II, and regulatory region of the HBx gene was more seen in cirrhotic patients than in chronic HBV cases. Novel mutations were detected in the HBx gene, causing amino acid substitutions; however, the clinical impact of these novel mutations is yet to be cleared.

Hepatitis B virus-induced hepatocarcinogenesis: A virological and oncological perspective

Hepatitis B virus (HBV) is a partially double-stranded DNA virus associated with hepatocellular carcinoma (HCC). The viral integration into the hepatocyte genome, the viral protein-induced oncogenesis, the increased hepatocyte turnover and the chronic inflammatory response towards HBV are all hypothesized mechanisms for the development of HCC. The fact that HBV infection and HCC prevalence show different correlations in various regions of the world indicates that there may be virus-independent phenomena for cancer development in these regions. From this point of view, it is important to review our knowledge and to examine the relationship between HBV and HCC in the light of current data. In this article, we investigate the relationship between HBV and HCC by presenting epidemiological and microbiological data, accompanied by the principles of viral oncogenesis.

Impact of Hepatitis B Virus Genetic Variation, Integration, and Lymphotropism in Antiviral Treatment and Oncogenesis

Chronic Hepatitis B Virus (HBV) infection poses a significant global health burden. Although, effective treatment and vaccinations against HBV are available, challenges still exist, particularly in the development of curative therapies. The dynamic nature and unique features of HBV such as viral variants, integration of HBV DNA into host chromosomes, and extrahepatic reservoirs are considerations towards understanding the virus biology and developing improved anti-HBV treatments. In this review, we highlight the importance of these viral characteristics in the context of treatment and oncogenesis. Viral genotype and genetic variants can serve as important predictive factors for therapeutic response and outcomes in addition to oncogenic risk. HBV integration, particularly in coding genes, is implicated in the development of hepatocellular carcinoma. Furthermore, we will discuss emerging research that has identified various HBV nucleic acids and infection markers within extrahepatic sites (lymphoid cells). Intriguingly, the presence of hepatocellular carcinoma (HCC)-associated HBV variants and viral integration within the lymphoid cells may contribute towards the development of extrahepatic malignancies. Improved understanding of these HBV characteristics will enhance the development of a cure for chronic HBV infection.

Differences in HBV Replication, APOBEC3 Family Expression, and Inflammatory Cytokine Levels Between Wild-Type HBV and Pre-core (G1896A) or Basal Core Promoter (A1762T/G1764A) Mutants

Background

Chronic hepatitis B virus (HBV) infection is the leading cause of hepatocellular carcinoma (HCC) world-wide. HBV variants, particularly the G1896A pre-core (PC) and A1762T/G1764A basal core promoter (BCP) mutations, are established risk factors for cirrhosis and HCC, but the molecular biological basis is unclear. We hypothesized that these variants result in differential HBV replication, APOBEC3 family expression, and cytokine/chemokine expression.

Methods

HepG2 cells were transfected with monomeric full-length containing wild-type, PC, or BCP HBV. Cells and supernatant were collected to analyze viral infection markers (i.e., HBsAg, HBeAg, HBV DNA, and RNA). Cellular APOBEC3 expression and activity was assessed by quantitative real-time (qRT)-PCR, immunoblot, differential DNA denaturation PCR, and sequencing. Cytokine/chemokines in the supernatant and in serum from 11 CHB carriers (4 non-cirrhotic; 7 cirrhotic and/or HCC) with predominantly wild-type, PC, or BCP variants were evaluated by Luminex.

Results

HBeAg expression was reduced in PC and BCP variants, and higher supernatant HBV DNA and HBV RNA levels were found with A1762T/G1764A vs. G1896A mutant (p < 0.05). Increased APOBEC3G protein levels in wild-type vs. mutant were not associated with HBV covalently closed circular DNA G-to-A hypermutations. Differences in cytokine/chemokine expression in culture supernatants, especially IL-13 were observed amongst the variants analyzed. Noticeable increases of numerous cytokines/chemokines, including IL-4 and IL-8, were observed in ex vivo serum collected from CHB carriers with PC mutant.

Conclusion

HBV sequence variation leads to differences in HBV protein production (HBeAg) and viral replication in addition to altered host innate antiviral restriction factor (APOBEC3) and cytokine/chemokine expression.

Oncogenic HBV variants and integration are present in hepatic and lymphoid cells derived from chronic HBV patients

The hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC), partly driven by viral integration and specific oncogenic HBV variants. However, the biological significance of HBV genomes within lymphoid cells (i.e., peripheral blood mononuclear cells, PBMCs) is unclear. Here, we collected available plasma, PBMC, liver, and tumor from 52 chronic HBV (CHB) carriers: 32 with HCC, 19 without HCC, and one with dendritic cell sarcoma, DCS. Using highly sensitive sequencing techniques, next generation sequencing, and AluPCR, we demonstrate that viral genomes (i.e., HBV DNA, RNA, and cccDNA), oncogenic variants, and HBV-host integration are often found in all sample types collected from 52 patients (including lymphoid cells and a DCS tumor). Viral integration was recurrently identified (n = 90 such hits) in genes associated with oncogenic consequences in lymphoid and liver cells. Further, HBV genomes increased in PBMCs derived from 7 additional (treated or untreated) CHB carriers after extracellular mitogen stimulation. Our study shows novel HBV molecular data and replication not only liver, but also within 63.8% of lymphoid cells analysed (including a representative lymphoid cell malignancy), that was enhanced in ex vivo stimulated PBMC.

HBV triggers APOBEC2 expression through miR‑122 regulation and affects the proliferation of liver cancer cells

Hepatitis B virus (HBV) infection is responsible for 50% of liver cancer cases globally; this disease is one of the leading causes of cancer‑associated mortality. One reported mechanism underlying the development of liver cancer is the mutation of tumor suppressor genes induced by the overexpression of apolipoprotein B mRNA‑editing enzyme catalytic subunit 2 (APOBEC2) in hepatocytes. In addition, it has been observed that HBV inhibited microRNA (miR)‑122 expression in hepatocytes; however, the molecular mechanisms involved in liver cancer development remain unknown and further investigations are required. In the present study, the mechanistic roles of HBV infection in modulating the expression of miR‑122 and APOBEC2, and the development of liver cancer, were investigated. Reverse transcription‑quantitative PCR and western blot analyses revealed that APOBEC2 expression was markedly upregulated following HBV infection. Of note, the expression profile of APOBEC2 in the Huh7 and HepG2 liver cancer cell lines opposed that of miR‑122; this miR is the most abundant miRNA in the liver and has been associated with hepatocarcinogenesis. Mechanistically, it was demonstrated via a dual‑luciferase assay that miR‑122 could specifically bind to the 3'‑untranslated region (3'UTR) of APOBEC2 mRNA, inhibiting its expression. Collectively, the findings of the present study may provide insight into the mechanistic role of HBV infection in modulating the expression of miR‑122, which targets the 3'UTR of APOBEC2 mRNA, subsequently inducing liver carcinogenesis.

Hepatocellular carcinoma in the noncirrhotic liver: a literature review

Development of hepatocellular carcinoma (HCC) is usually preceded by chronic liver injury and ongoing liver diseases. Liver cirrhosis reflects the outcome of long-term liver injury and is associated with an increased risk of developing HCC. However, HCC also arises in individuals without cirrhosis and bears several characteristics distinct from HCC in the cirrhotic liver. The molecular characteristics, prognosis, and surveillance of noncirrhotic HCC have not been adequately studied. In this review, we update readers and researchers in the field with the latest understanding of the epidemiology, etiology, clinical features, diagnosis, treatment strategies, prognosis, and surveillance of noncirrhotic HCC.

Analysis of HBV X gene quasispecies characteristics by next-generation sequencing and cloning-based sequencing and its association with hepatocellular carcinoma progression

OBJECTIVES

This study aimed to describe the differences between next-generation sequencing (NGS) and cloning-based sequencing (CBS) in HBX quasispecies research and primitively investigate the relationship between the dominant HBX quasispecies and hepatocellular carcinoma (HCC).

METHODS

A total of 12 serum samples were collected. Serum hepatitis B virus (HBV) DNA was extracted, and the HBV X-region (HBX) was amplified by nested polymerase chain reaction (PCR). The PCR products were simultaneously tested with NGS and CBS to detect quasispecies of the HBX.

RESULTS

A total of 9348 eligible quasispecies sequences were obtained by NGS, which were much larger than the 98 of that by CBS. By the phylogenetic tree, the dominant quasispecies sequence of each sample could be found, although they had several nucleotides differences between the dominant quasispecies sequences found by CBS and NGS. By comparing the quasispecies heterogeneity, it was found that the quasispecies complexity value of HBV X-region obtained by NGS was higher than CBS (P < 0.05). The diversity values, including d, dS, dN, an d d N/ dS obtained by NGS were lower than by CBS (all of P < 0.01). The relativity of Spearman(rs) in d, dS, and dN were statistically significant (rs_ d = 0.865, P = 0.001; rs_ dS = 0.722, P = 0.014; and rs_ dN = 0.738, P = 0.011, respectively). There were 21 different bases between the HBX quasispecies of case A and control B.

CONCLUSION

The results of this can be used as guidance when researchers plan to choose a suitable method to study quasispecies, especially the HBV X gene quasispecies. Some high-risk mutations of HBX quasispecies were also found in this study and their relationship with HCC need deeper exploration.

The Correlation Between Hepatitis B Virus Precore/Core Mutations and the Progression of Severe Liver Disease

Viral mutations acquired during the course of chronic hepatitis B virus (HBV) infection are known to be associated with the progression and severity of HBV-related liver disease. This study of HBV-infected Saudi Arabian patients aimed to identify amino acid substitutions within the precore/core (preC/C) region of HBV, and investigate their impact on disease progression toward hepatocellular carcinoma (HCC). Patients were categorized according to the severity of their disease, and were divided into the following groups: inactive HBV carriers, active HBV carriers, liver cirrhosis patients, and HCC patients. Two precore mutations, W28^* and G29D, and six core mutations, F24Y, E64D, E77Q, A80I/T/V, L116I, and E180A were significantly associated with the development of cirrhosis and HCC. Six of the seven significant core mutations that were identified in this study were located within immuno-active epitopes; E77Q, A80I/T/V, and L116I were located within B-cell epitopes, and F24Y, E64D, and V91S/T were located within T-cell epitopes. Multivariate risk analysis confirmed that the core mutations A80V and L116I were both independent predictors of HBV-associated liver disease progression. In conclusion, our data show that mutations within the preC/C region, particularly within the immuno-active epitopes, may contribute to the severity of liver disease in patients with chronic hepatitis. Furthermore, we have identified several distinct preC/C mutations within the study population that affect the clinical manifestation and progression of HBV-related disease. The specific identity of HBV mutations that are associated with severe disease varies between different ethnic populations, and so the specific preC/C mutations identified here will be useful for predicting clinical outcomes and identifying the HBV-infected patients within the Saudi population that are at high risk of developing HCC.

Applications of next-generation sequencing analysis for the detection of hepatocellular carcinoma-associated hepatitis B virus mutations

BACKGROUND

Next-generation sequencing (NGS) is a powerful and high-throughput method for the detection of viral mutations. This article provides a brief overview about optimization of NGS analysis for hepatocellular carcinoma (HCC)-associated hepatitis B virus (HBV) mutations, and hepatocarcinogenesis of relevant mutations.

MAIN BODY

For the application of NGS analysis in the genome of HBV, four noteworthy steps were discovered in testing. First, a sample-specific reference sequence was the most effective mapping reference for NGS. Second, elongating the end of reference sequence improved mapping performance at the end of the genome. Third, resetting the origin of mapping reference sequence could probed deletion mutations and variants at a certain location with common mutations. Fourth, using a platform-specific cut-off value to distinguish authentic minority variants from technical artifacts was found to be highly effective. One hundred and sixty-seven HBV single nucleotide variants (SNVs) were found to be studied previously through a systematic literature review, and 12 SNVs were determined to be associated with HCC by meta-analysis. From comprehensive research using a HBV genome-wide NGS analysis, 60 NGS-defined HCC-associated SNVs with their pathogenic frequencies were identified, with 19 reported previously. All the 12 HCC-associated SNVs proved by meta-analysis were confirmed by NGS analysis, except for C1766T and T1768A which were mainly expressed in genotypes A and D, but including the subgroup analysis of A1762T. In the 41 novel NGS-defined HCC-associated SNVs, 31.7% (13/41) had cut-off values of SNV frequency lower than 20%. This showed that NGS could be used to detect HCC-associated SNVs with low SNV frequency. Most SNV II (the minor strains in the majority of non-HCC patients) had either low (< 20%) or high (> 80%) SNV frequencies in HCC patients, a characteristic U-shaped distribution pattern. The cut-off values of SNV frequency for HCC-associated SNVs represent their pathogenic frequencies. The pathogenic frequencies of HCC-associated SNV II also showed a U-shaped distribution. Hepatocarcinogenesis induced by HBV mutated proteins through cellular pathways was reviewed.

CONCLUSION

NGS analysis is useful to discover novel HCC-associated HBV SNVs, especially those with low SNV frequency. The hepatocarcinogenetic mechanisms of novel HCC-associated HBV SNVs defined by NGS analysis deserve further investigation.

Deep sequencing shows low-level oncogenic hepatitis B virus variants persists post-liver transplant despite potent anti-HBV prophylaxis

Recent studies suggest that withdrawal of hepatitis B immune globulin (HBIG) and nucleos(t)ide analogues (NA) prophylaxis may be considered in HBV surface antigen (HBsAg)-negative liver transplant (LT) recipients with a low risk of disease recurrence. However, the frequency of occult HBV infection (OBI) and HBV variants after LT in the current era of potent NA therapy is unknown. Twelve LT recipients on prophylaxis were tested in matched plasma and peripheral blood mononuclear cells (PBMCs) for HBV quasispecies by in-house nested PCR and next-generation sequencing of amplicons. HBV covalently closed circular DNA (cccDNA) was detected in Hirt DNA isolated from PBMCs with cccDNA-specific primers and confirmed by nucleic acid hybridization and Sanger sequencing. HBV mRNA in PBMC was detected with reverse-transcriptase nested PCR. In LT recipients on immunosuppressive therapy (10/12 male; median age 57.5 [IQR: 39.8-66.5]; median follow-up post-LT 60 months; 6 pre-LT hepatocellular carcinoma [HCC]), 9 were HBsAg-. HBV DNA was detected in all plasma and PBMC tested; cccDNA and/or mRNA was detected in the PBMC of 10/12 patients. Significant HBV quasispecies diversity (ie 143-2212 nonredundant HBV species) was noted in both sites, and single nucleotide polymorphisms associated with cirrhosis and HCC were detected at varying frequencies. In conclusion, OBI and HBV variants associated with severe liver disease persist in LT recipients on prophylaxis. Although HBV control and cccDNA transcriptional silencing may occur despite immunosuppression, complete virological eradication does not occur in LT recipients with a history of HBV-related end-stage liver disease.

Update Treatment for HBV Infection and Persistent Risk for Hepatocellular Carcinoma: Prospect for an HBV Cure

Since the discovery of the hepatitis B virus (HBV) by Blumberg et al. in 1965, its genome, sequence, epidemiology, and hepatocarcinogenesis have been elucidated. Globally, hepatitis B virus (HBV) is still responsible for the majority of hepatocellular carcinoma (HCC). HCC is the sixth-most common cancer in the world and the second-most common cancer death. The ultimate goal of treating HBV infection is the prevention of HCC. Fortunately, anti-HBV treatment with nucleos(t)ide analogues (NAs), which began with lamivudine in 1998, has resulted in remarkable improvements in the survival of patients with chronic hepatitis B and a reduced incidence of HCC. These results were documented with lamivudine, entecavir, and tenofovir. Nonetheless, as the duration of antiviral treatment increases, the risk for HCC still remains despite undetectable HBV DNA in serum, as reported by different investigators with observation up to 4⁻5 years. In our own experience, we are witnessing the development of HCC in patients who have received antiviral treatment. Some have enjoyed negative serum HBV DNA for over 12 years before developing HCC. Current treatment with NAs can effectively suppress the replication of the virus but cannot eradicate the covalently closed circular DNA (cccDNA) that is within the nucleus of hepatocytes. There still remains a great need for a cure for HBV. Fortunately, several compounds have been identified that have the potential to eradicate HBV, and there are ongoing clinical trials in progress in their early stages.

Deep sequencing of HBV pre-S region reveals high heterogeneity of HBV genotypes and associations of word pattern frequencies with HCC

Hepatitis B virus (HBV) infection is a common problem in the world, especially in China. More than 60–80% of hepatocellular carcinoma (HCC) cases can be attributed to HBV infection in high HBV prevalent regions. Although traditional Sanger sequencing has been extensively used to investigate HBV sequences, NGS is becoming more commonly used. Further, it is unknown whether word pattern frequencies of HBV reads by Next Generation Sequencing (NGS) can be used to investigate HBV genotypes and predict HCC status. In this study, we used NGS to sequence the pre-S region of the HBV sequence of 94 HCC patients and 45 chronic HBV (CHB) infected individuals. Word pattern frequencies among the sequence data of all individuals were calculated and compared using the Manhattan distance. The individuals were grouped using principal coordinate analysis (PCoA) and hierarchical clustering. Word pattern frequencies were also used to build prediction models for HCC status using both K-nearest neighbors (KNN) and support vector machine (SVM). We showed the extremely high power of analyzing HBV sequences using word patterns. Our key findings include that the first principal coordinate of the PCoA analysis was highly associated with the fraction of genotype B (or C) sequences and the second principal coordinate was significantly associated with the probability of having HCC. Hierarchical clustering first groups the individuals according to their major genotypes followed by their HCC status. Using cross-validation, high area under the receiver operational characteristic curve (AUC) of around 0.88 for KNN and 0.92 for SVM were obtained. In the independent data set of 46 HCC patients and 31 CHB individuals, a good AUC score of 0.77 was obtained using SVM. It was further shown that 3000 reads for each individual can yield stable prediction results for SVM. Thus, another key finding is that word patterns can be used to predict HCC status with high accuracy. Therefore, our study shows clearly that word pattern frequencies of HBV sequences contain much information about the composition of different HBV genotypes and the HCC status of an individual.

HBV infection can lead to many liver complications including hepatocellular carcinoma (HCC), one of the most common liver cancers in China. High-throughput sequencing technologies have recently been used to study the genotype sequence compositions of HBV infected individuals and to distinguish chronic HBV (CHB) infection from HCC. We used NGS to sequence the pre-S region of a large number of CHB and HCC individuals and designed novel word pattern based approaches to analyze the data. We have several surprising key findings. First, most HBV infected individuals contained mixtures of genotypes B and C sequences. Second, multi-dimensional scaling (MDS) analysis of the data showed that the first principal coordinate was closely associated with the fraction of genotype B (or C) sequences and the second principal coordinate was highly associated with the probability of HCC. Third, we also designed K-nearest neighbors (KNN) and support vector machine (SVM) based classifiers for CHB and HCC with high prediction accuracy. The results were validated in an independent data set.

Hepatocellular carcinoma-associated single-nucleotide variants and deletions identified by the use of genome-wide high-throughput analysis of hepatitis B virus

This study investigated hepatitis B virus (HBV) single-nucleotide variants (SNVs) and deletion mutations linked with hepatocellular carcinoma (HCC). Ninety-three HCC patients and 108 non-HCC patients were enrolled for HBV genome-wide next-generation sequencing (NGS) analysis. A systematic literature review and a meta-analysis were performed to validate NGS-defined HCC-associated SNVs and deletions. The experimental results identified 60 NGS-defined HCC-associated SNVs, including 41 novel SNVs, and their pathogenic frequencies. Each SNV was specific for either genotype B (n = 24) or genotype C (n = 34), except for nt53C, which was present in both genotypes. The pathogenic frequencies of these HCC-associated SNVs showed a distinct U-shaped distribution pattern. According to the meta-analysis and literature review, 167 HBV variants from 109 publications were categorized into four levels (A-D) of supporting evidence that they are associated with HCC. The proportion of NGS-defined HCC-associated SNVs among these HBV variants declined significantly from 75% of 12 HCC-associated variants by meta-analysis (Level A) to 0% of 10 HCC-unassociated variants by meta-analysis (Level D) (P < 0.0001). PreS deletions were significantly associated with HCC, in terms of deletion index, for both genotypes B (P = 0.030) and C (P = 0.049). For genotype C, preS deletions involving a specific fragment (nt2977-3013) were significantly associated with HCC (HCC versus non-HCC, 6/34 versus 0/32, P = 0.025). Meta-analysis of preS deletions showed significant association with HCC (summary odds ratio 3.0; 95% confidence interval 2.3-3.9). Transfection of Huh7 cells showed that all of the five novel NGS-defined HCC-associated SNVs in the small surface region influenced hepatocarcinogenesis pathways, including endoplasmic reticulum-stress and DNA repair systems, as shown by microarray, real-time polymerase chain reaction and western blot analysis. Their carcinogenic mechanisms are worthy of further research. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

F221Y mutation in hepatitis B virus reverse transcriptase is associated with hepatocellular carcinoma prognosis following liver resection

Hepatitis B virus (HBV) reverse transcriptase (RT) is encoded by the polymerase gene in the reverse transcriptase region, which overlaps with the S gene. The association between mutations of HBV RT and the pathobiological features of hepatocellular carcinoma (HCC) remain to be elucidated. The present study aimed to examine mutations in this region of the HBV genome and its clinical significance. Briefly, HBV total DNA was extracted from 84 pairs of HCC tumor tissue and corresponding adjacent non‑tumor tissue samples. The RT/S regions (nt130‑1161) were amplified and sequenced using the Sanger method, and associations between RT mutations and the clinical characteristics of patients with HCC were analyzed. Finally, 27 and 29 mutations with frequencies >5% were identified in the RT and S regions, respectively. The rtF221Y variation and a tumor size >8 cm were found to be independent risk factors for the postoperative recurrence of HCC, with hazard ratios of 2.345 (95% CI, 1.391‑3.953; P=0.001) and 1.838 (95% CI, 1.069‑3.161; P=0.028), respectively. rtF221Y was also an independent risk factor for poor overall survival rates (HR=2.557; 95% CI, 1.344‑4.866; P=0.004). The mutation of R122 K in the HBV S protein was closely associated with tumor recurrence (P<0.001). As a result, rtF221Y was identified as a risk factor for poor prognosis and may be a potential viral marker for predicting prognosis in HCC.

Hepatitis B virus strains from Rwandan blood donors are genetically similar and form one clade within subgenotype A1

BACKGROUND

Rwanda is a central African country with about 12 million inhabitants. The 1994 genocide against the Tutsi destroyed much of the infrastructure, including the health system. Although this has improved significantly, many challenges remain to be addressed. In this study, the prevalence of serological markers of past and ongoing hepatitis B virus (HBV) infection and HBV vaccine related immunity was investigated in samples from blood donors from all regions of Rwanda.

METHODS

The results from hepatitis B surface antigen (HBsAg) analyses of all (45,061) blood donations collected countrywide in 2014 from 13,637 first time and 31,424 repeat blood donors were compiled. Samples from 581 HBsAg negative blood donors were selected for further analysis for antibodies against HBV, anti-HBs and anti-HBc. Additional 139 samples from HBsAg positive donors were analyzed for HBeAg/anti-HBe (132 samples) and for HBV DNA. The S-gene was amplified by PCR, products sequenced, and phylogenetic analysis was performed.

RESULTS

HBsAg was found in 4.1% of first time donors with somewhat higher prevalence among those from the Central and Eastern regions than from other parts of the country. Indications of past infection was found in 21% of the HBsAg negative donors, 4.3% had only anti-HBs suggesting HBV vaccination. HBeAg was detected in 28 (21%), anti-HBe in 97 (73%), and both HBeAg and anti-HBe in 4 of 132 HBsAg positive donors. HBV DNA was found in 85 samples, and the complete S-gene was sequenced in 58 of those. Phylogenetic analysis of the sequences revealed that all HBV strains belonged to subgenotype A1, and formed one clade in the phylogenetic tree. In addition, 12 strains from first time donors had a unique 18 amino acid deletion in the N-terminal part of the pre-S2 region.

CONCLUSION

This study indicated that the prevalence of hepatitis B is intermediate in Rwanda and that the vaccination coverage is relatively low in young adults. All surveyed Rwandan blood donors were infected with similar subgenotype A1 strains, and a high frequency of those with anti-HBe had detectable HBV DNA. Several strains had in addition a unique pre-S2 deletion, the virulence of which needs to be further studied.

Clinical features of HBsAg seroclearance in hepatitis B virus carriers in South Korea: A retrospective longitudinal study

AIM

To investigate the characteristic features of hepatitis B surface antigen (HBsAg) seroclearance among Korean hepatitis B virus (HBV) carriers.

METHODS

Carriers with HBsAg seroclearance were selected by analyzing longitudinal data collected from 2003 to 2015. The period of time from enrollment to the negative conversion of HBsAg (HBsAg-NC) was compared by stratifying various factors, including age, sex, hepatitis B e antigen (HBeAg), HBV DNA, sequential changes in the signal-to-cutoff ratio of HBsAg (HBsAg-SCR), as measured by qualitative HBsAg assay, and chronic liver disease on ultrasonography (US-CLD). Quantification of HBV DNA and HBsAg (HBsAg-QNT) in the serum was performed by commercial assay.

RESULTS

Among the 1919 carriers, 90 (4.7%) exhibited HBsAg-NC at 6.2 ± 3.6 years after registration, with no differences observed among the different age groups. Among these carriers, the percentages of those with asymptomatic liver cirrhosis (LC) and hepatocellular carcinoma (HCC) at registration were 31% and 7.8%, respectively. The frequency of HBsAg-NC significantly differed according to the HBV DNA titer and US-CLD. HBeAg influenced HBsAg-NC in the 40-50 and 50-60 year age groups. HBsAg-SCR < 1000 was correlated with an HBsAg-QNT < 200 IU/mL. A gradual decrease in the HBsAg-SCR to < 1000 predicted HBsAg-NC. Six patients developed HCC after registration, including two before and four after HBsAg-NC. The rate at which the patients developed new HCC after HBsAg seroclearance was 4.8%. LC with excessive drinking and vertical infection were found to be risk factors for HCC in the HBsAg-NC group.

CONCLUSION

HCC surveillance should be continued after HBsAg seroclearance. An HBsAg-SCR < 1000 and its decrease in sequential testing are worth noting as predictive markers of HBsAg loss.

Potential Susceptibility Mutations in C Gene for Hepatitis B-Related Hepatocellular Carcinoma Identified by a Two-Stage Study in Qidong, China

A two stage study was conducted to explore new potential mutations in the full genome of hepatitis B virus (HBV) on the progression of hepatocellular carcinoma (HCC) in Qidong, China. In stage 1, full genomes of HBV were compared between 30 HCC cases and 30 controls. In stage 2, an independent case-control study including 100 HCC cases and 100 controls was enrolled to verify the relationship between hot-spot mutations and HCC development. Furthermore, a longitudinal study was conducted on 11 HCC cases with serial serum samples available before HCC diagnosis. A total of 10 mutations (including pre-S2 start codon mutation and pre-S deletion in pre-S gene, G1613A, C1653T, A1762T, and G1764A mutations in X gene, A2159G, A2189Y, G2203W, and C2288R mutations in C gene) showed an increased risk of HCC. In the validation study, pre-S deletion, C1653T, A1762T/G1764A, A2159G, A2189Y, G2203W, and C2288R mutations were associated with increased HCC risk in univariate analysis. Multivariate analysis indicated that pre-S deletion, A1762T/G1764A, A2159G, and A2189Y mutations were independently related with HCC development. Moreover, a significant biological gradient of HCC risk by number of mutations in the C gene was observed. Longitudinal observation demonstrated a gradual combination of the above mutations accumulated during the progression of HCC.

HBx mutations promote hepatoma cell migration through the Wnt/β-catenin signaling pathway

HBx mutations (T1753V, A1762T, G1764A, and T1768A) are frequently observed in hepatitis B virus (HBV)‐related hepatocellular carcinoma (HCC). Aberrant activation of the Wnt/β‐catenin signaling pathway is involved in the development of HCC. However, activation of the Wnt/β‐catenin signaling pathway by HBx mutants has not been studied in hepatoma cells or HBV‐associated HCC samples. In this study, we examined the effects of HBx mutants on the migration and proliferation of HCC cells and evaluated the activation of Wnt/β‐catenin signaling in HBx‐transfected HCC cells and HBV‐related HCC tissues. We found that HBx mutants (T, A, TA, and Combo) promoted the migration and proliferation of hepatoma cells. The HBx Combo mutant potentiated TOP‐luc activity and increased nuclear translocation of β‐catenin. Moreover, the HBx Combo mutant increased and stabilized β‐catenin levels through inactivation of glycogen synthase kinase‐3β, resulting in upregulation of downstream target genes such as c‐Myc,CTGF, and WISP2. Enhanced activation of Wnt/β‐catenin was found in HCC tissues with HBx TA and Combo mutations. Knockdown of β‐catenin effectively abrogated cell migration and proliferation stimulated by the HBx TA and Combo mutants. Our results indicate that HBx mutants, especially the Combo mutant, allow constitutive activation of the Wnt signaling pathway and may play a pivotal role in HBV‐associated hepatocarcinogenesis.

Precore/core region mutations of hepatitis B virus related to clinical severity

Despite the availability of an effective vaccine, hepatitis B virus (HBV) infection remains a major health problem, with more than 350 million chronically infected people worldwide and over 1 million annual deaths due to cirrhosis and liver cancer. HBV mutations are primarily generated due both to a lack of proofreading capacity by HBV polymerase and to host immune pressure, which is a very important factor for predicting disease progression and therapeutic outcomes. Several types of HBV precore/core (preC/C) mutations have been described to date. The host immune response against T cells drives mutation in the preC/C region. Specifically, preC/C mutations in the MHC class II restricted region are more common than in other regions and are significantly related to hepatocellular carcinoma. Certain mutations, including preC G1896A, are also significantly related to HBeAg-negative chronic infection. This review article mainly focuses on the HBV preC/C mutations that are related to disease severity and on the HBeAg serostatus of chronically infected patients.

Naturally occurring basal core promoter A1762T/G1764A dual mutations increase the risk of HBV-related hepatocellular carcinoma: a meta-analysis

Basal core promoter (BCP) A1762T/G1764A dual mutations in hepatocarcinogenesis remain controversial. Published studies up to June 1, 2015 investigating the frequency of A1762T/G1764A dual mutations from chronic hepatitis B virus (HBV) infection, including hepatocellular carcinoma (HCC), were systematically identified. A total of 10,240 patients with chronic HBV infection, including 3729 HCC cases, were included in 52 identified studies. HCC patients had a higher frequency of BCP A1762T/G1764A dual mutations compared with asymptomatic HBsAg carriers (ASC) and patients with chronic hepatitis B (CHB) and liver cirrhosis (LC) (OR = 5.59, P < 0.00001; OR = 2.87, P < 0.00001; OR = 1.55, P = 0.02, respectively). No statistically significant difference was observed in the frequency of A1762T/G1764A dual mutations in cirrhotic HCC versus non-cirrhotic HCC patients (OR = 2.06, P = 0.05). Chronic HBV-infected patients and HCC patients with genotype B had a significantly lower risk of A1762T/G1764A dual mutations compared with patients with genotype C (OR = 0.30, P < 0.0001 and OR = 0.34, P = 0.04, respectively). In HBV genotype C subjects, A1762T/G1764A dual mutations contributed to significantly higher risk for HCC developing compared with non-mutation ones (OR = 3.47, P < 0.00001). In conclusion, A1762T/G1764A dual mutations increase the risk of HBV-related hepatocellular carcinoma, particularly in an HBV genotype C population, even without progression to cirrhosis.

Genetic variation of hepatitis B virus and its significance for pathogenesis

Hepatitis B virus (HBV) has a worldwide distribution and is endemic in many populations. Due to its unique life cycle which requires an error-prone reverse transcriptase for replication, it constantly evolves, resulting in tremendous genetic variation in the form of genotypes, sub-genotypes, and mutations. In recent years, there has been considerable research on the relationship between HBV genetic variation and HBV-related pathogenesis, which has profound implications in the natural history of HBV infection, viral detection, immune prevention, drug treatment and prognosis. In this review, we attempted to provide a brief account of the influence of HBV genotype on the pathogenesis of HBV infection and summarize our current knowledge on the effects of HBV mutations in different regions on HBV-associated pathogenesis, with an emphasis on mutations in the preS/S proteins in immune evasion, occult HBV infection and hepatocellular carcinoma (HCC), mutations in polymerase in relation to drug resistance, mutations in HBV core and e antigen in immune evasion, chronicalization of infection and hepatitis B-related acute-on-chronic liver failure, and finally mutations in HBV x proteins in HCC.

Hepatitis B virus genotype, mutations, human leukocyte antigen polymorphisms and their interactions in hepatocellular carcinoma: a multi-centre case-control study

Three genome-wide association studies (GWAS) have been conducted on the genetic susceptibility of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), two of which consistently identified tagging single nucleotide polymorphisms (SNPs) around HLA-DQ/DR. In contrast, large multi-centre association studies between HBV genotype, mutations and the risk of HCC are relatively rare, and their interactions with host variants are even less. We performed a multi-centre study of 1,507 HBV-related HCC cases and 1,560 HBV persistent carriers as controls to evaluate the effects of HBV genotype, mutations, GWAS-identified HLA-DQ/DR SNPs (rs9272105 and rs9275319) and their interactions on HCC risk. We found HBV genotype C was more frequent in HBV-related HCC. And 11 HBV hotspot mutations were independently and significantly associated with HCC risk. We also detected significant interactions of rs9272105 with both the HBV genotype and mutations. Through stepwise regression analysis, HBV genotype, the 11 mutations, HLA-DQ/DR SNPs, and the interaction of rs9272105 with mutation A1752G were all entered into the HCC prediction model, and the area under the curve for the panel including the HLA-DQ/DR SNPs, HBV genotype and mutations was 0.840. The HBV genotype, the mutations and the HLA-DQ/DR SNPs may serve as biomarkers for the surveillance of HBV persistent carriers.

CRISPR/Cas9-based tools for targeted genome editing and replication control of HBV

Hepatitis B virus (HBV) infection remains a major global health problem because current therapies rarely eliminate HBV infections to achieve a complete cure. A different treatment paradigm to effectively clear HBV infection and eradicate latent viral reservoirs is urgently required. In recent years, the development of a new RNA-guided gene-editing tool, the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease 9) system, has greatly facilitated site-specific mutagenesis and represents a very promising potential therapeutic tool for diseases, including for eradication of invasive pathogens such as HBV. Here, we review recent advances in the use of CRISPR/Cas9, which is designed to target HBV specific DNA sequences to inhibit HBV replication and to induce viral genome mutation, in cell lines or animal models. Advantages, limitations and possible solutions, and proposed directions for future research are discussed to highlight the opportunities and challenges of CRISPR/Cas9 as a new, potentially curative therapy for chronic hepatitis B infection.

Quantitative evaluation of hepatitis B virus mutations and hepatocellular carcinoma risk: a meta-analysis of prospective studies

BACKGROUND

The temporal relationship between hepatitis B virus (HBV) mutations and hepatocellular carcinoma (HCC) remains unclear.

METHODS

We conducted a meta-analysis including cohort and nested case-control studies to prospectively examine the HCC risk associated with common variants of HBV in the PreS, Enhancer II, basal core promoter (BCP) and precore regions. Pertinent studies were identified by searching PubMed, Web of Science and the Chinese Biological Medicine databases through to November 2014. Study-specific risk estimates were combined using fixed or random effects models depending on whether significant heterogeneity was detected.

RESULTS

Twenty prospective studies were identified, which included 8 cohort and 12 nested case-control studies. There was an increased risk of HCC associated with any PreS mutations with a pooled relative risk (RR) of 3.82 [95% confidence interval (CI): 2.59-5.61]. The pooled-RR for PreS deletion was 3.98 (95% CI: 2.28-6.95), which was higher than that of PreS2 start codon mutation (pooled-RR=2.63, 95% CI: 1.30-5.34). C1653T in Enhancer II was significantly associated with HCC risk (pooled-RR=1.83; 95% CI: 1.21-2.76). For mutations in BCP, statistically significant pooled-RRs of HCC were obtained for T1753V (pooled-RR=2.09; 95% CI: 1.49-2.94) and A1762T/G1764A double mutations (pooled-RR=3.11; 95% CI: 2.08-4.64). No statistically significant association with HCC risk was observed for G1896A in the precore region (pooled-RR=0.77; 95% CI: 0.47-1.26).

CONCLUSIONS

This study demonstrated that PreS mutations, C1653T, T1753V, and A1762T/G1764A, were associated with an increased risk of HCC. Clinical practices concerning the HCC risk prediction and diagnosis may wish to focus on patients with these mutations.

Aligning to the sample-specific reference sequence to optimize the accuracy of next-generation sequencing analysis for hepatitis B virus

Background

Hepatitis B virus (HBV) quasispecies are crucial in the pathogenesis of chronic liver disease. Next-generation sequencing (NGS) is powerful for identifying viral quasispecies. To improve mapping quality and single nucleotide variant (SNV) calling accuracy in the NGS analysis of HBV, we compared different mapping references, including the sample-specific reference sequence, same genotype sequences and different genotype sequences, according to the sample.

Methods

Real Illumina HBV datasets from 86 patients, and simulated datasets from 158 HBV strains in the GenBank database, were used to assess mapping quality. SNV calling accuracy was evaluated using different mapping references to align Real Illumina datasets from a single HBV clone.

Results

Using the sample-specific reference sequence as a mapping reference produced the largest number of mappable reads and coverages. With a different genotype mapping reference, the consensus sequence derived from the Real Illumina datasets of the single HBV clone showed 21 false SNV callings in polymerase and surface genes, the regions most divergent between the mapping reference and this HBV clone. A ~6 % coverage of most of these false SNVs was yielded even with a same genotype mapping reference, but none with the sample-specific reference sequence.

Conclusions

Using sample-specific reference sequences as a mapping reference in NGS analysis optimized mapping quality and the SNV calling accuracy for HBV quasispecies.

Electronic supplementary material

The online version of this article (doi:10.1007/s12072-015-9645-x) contains supplementary material, which is available to authorized users.

Novel therapeutic approaches for hepatitis B virus covalently closed circular DNA

Hepatitis B virus (HBV) infection is a major global health problem. Although current therapies, such as the use of nucleos(t)ide analogs, inhibit HBV replication efficiently, they do not eliminate covalently closed circular DNA (cccDNA), which persists in hepatocyte nuclei. As HBV cccDNA is a viral transcription template, novel therapeutic approaches to directly target HBV cccDNA are necessary to completely eradicate persistent HBV infections. HBV cccDNA levels in HBV-infected human liver cells are extremely low; thus, more reliable and simple measurement methods are needed to correctly monitor their levels during therapeutic treatment. Although reverse transcription-polymerase chain reaction or Southern blot procedures are currently used in research studies, these methods are not completely reliable and are also time-consuming and labor-intensive. Genome editing technologies, such as zinc finger nucleases, transcription activator-like effector nucleases, and the clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) system, which are designed to target specific DNA sequences, represent highly promising potential therapeutic tools. In particular, the CRISPR/Cas9 system is an easily customizable sequence-specific nuclease with high flexibility and may be the most feasible approach to target HBV cccDNA. Further research to develop easier, safer, and more effective protocols should be pursued.

Key role of hepatitis B virus mutation in chronic hepatitis B development to hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC). The HBV mutations, which include point mutation, deletion, insertion and truncation mutation of HBV gene in 4 open reading frames (S, C, P, X), are closely associated with HCC pathogenesis. Some mutations accumulated during chronic HBV infection could be regarded as a biomarker to predict the occurrence of HCC. The detection of the mutations in clinical practice could be helpful for defining better preventive and therapeutic strategies and, moreover, predicting the progression of liver disease.

Clinical utility of complex mutations in the core promoter and proximal precore regions of the hepatitis B virus genome

The core promoter and proximal precore regions are the most complex portions of the hepatitis B virus (HBV) genome. These regions cooperatively regulate viral replication and differentially regulate the synthesis of the viral proteins E, core, and X. Multiple mutations in these regions are associated with the persistency of viral infection and the development of cirrhosis and hepatocellular carcinoma (HCC). In South Korea, nearly all HBVs are classified as HBV genotype C2; the majority of these viruses have the basal core promoter double mutation, a precore stop mutation, or both. These mutations may play a role in the alteration of viral and clinical features, and abundant and complex mutations are particularly prevalent in the core promoter and proximal precore regions. We previously demonstrated that the accumulation of ≥ 6 mutations at eight key nucleotides located in these regions (G1613A, C1653T, T1753V, A1762T, G1764A, A1846T, G1896A, and G1899A) is a useful marker to predict the development of HCC regardless of advanced liver disease. In addition, certain mutation combinations were predominant in cases with ≥ 4 mutations. In cases with ≤ 5 mutations, a low Hepatitis B e antigen titer (< 35 signal to noise ratio) was indicative of HCC risk. Viral mutation data of the single HBV genotype C2 suggest that the combined effect of the number and pattern of mutations in the core promoter and proximal precore regions is helpful in predicting HCC risk.

Novel point and combo-mutations in the genome of hepatitis B virus-genotype D: characterization and impact on liver disease progression to hepatocellular carcinoma

Background

The contribution of chronic hepatitis B virus (HBV) infection in the pathogenesis of hepatocellular carcinoma (HCC) through progressive stages of liver fibrosis is exacerbated by the acquisition of naturally occurring mutations in its genome. This study has investigated the prevalence of single and combo mutations in the genome of HBV-genotype D from treatment naïve Indian patients of progressive liver disease stages and assessed their impact on the disease progression to HCC.

Methods

The mutation profile was determined from the sequence analysis of the full-length HBV genome and compared with the reference HBV sequences. SPSS 16.0 and R software were used to delineate their statistical significance in predicting HCC occurrence.

Results

Age was identified as associated risk factor for HCC development in chronic hepatitis B (CHB) patients (p≤0.01). Beyond the classical mutations in basal core promoter (BCP) (A1762T/G1764A) and precore (G1862T), persistence of progressively accumulated mutations in enhancer-I, surface, HBx and core were showed significant association to liver disease progression. BCP_T1753C, core_T147C, surface_L213I had contributed significantly in the disease progression to HCC (p<0.05) in HBeAg positive patients whereas precore_T1858C, core_I116L, core_P130Q and preS1_S98T in HBeAg negative patients. Furthermore, the effect of individual mutation was magnified by the combination with A1762T/G1764A in HCC pathogenesis. Multivariate risk analysis had confirmed that core_P130Q [OR 20.71, 95% CI (1.64–261.77), p = 0.019] in B cell epitope and core_T147C [OR 14.58, 95% CI (1.17–181.76), p = 0.037] in CTL epitope were two independent predictors of HCC in HBeAg positive and negative patients respectively.

Conclusions

Thus distinct pattern of mutations distributed across the entire HBV genome may be useful in predicting HCC in high-risk CHB patients and pattern of mutational combinations may exert greater impact on HCC risk prediction more accurately than point mutations and hence these predictors may support the existing surveillance strategies in proper management of the patients.

DNA markers in molecular diagnostics for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the one of the leading causes of cancer mortality in the world, mainly due to the difficulty of early detection and limited therapeutic options. The implementation of HCC surveillance programs in well-defined, high-risk populations were only able to detect about 40-50% of HCC at curative stages (Barcelona Clinic Liver Cancer stages 0 & 1) due to the low sensitivities of the current screening methods. The advance of sequencing technologies has identified numerous modifications as potential candidate DNA markers for diagnosis/surveillance. Here we aim to provide an overview of the DNA alterations that result in activation of cancer pathways known to potentially drive HCC carcinogenesis and to summarize performance characteristics of each DNA marker in the periphery (blood or urine) for HCC screening.

Hepatitis B Virus-Related Hepatocellular Carcinoma: Pathogenic Mechanisms and Novel Therapeutic Interventions

BACKGROUND

Infection with the hepatitis B virus (HBV) is one of most important risk factors for hepatocellular carcinoma (HCC). Indeed, HBV is considered a group 1 human carcinogen and is a highly oncogenic agent. HBV cannot be effectively controlled or completely eliminated, so chronic HBV infection is a public health challenge worldwide.

SUMMARY

It is now believed that HBV-induced HCC involves a complex interaction between multiple viral and host factors. Many factors contribute to HBV-associated HCC, including products of HBV, viral integration and mutation, and host susceptibility. This review outlines the main pathogenic mechanisms with a focus on those that suggest novel targets for the prevention and treatment of HCC.

KEY MESSAGE

HBV infection is an important risk factor for HCC. Understanding the interaction between viral and host factors in HBV-induced HCC will reveal potential targets for future therapies.

PRACTICAL IMPLICATIONS

The two main therapeutic strategies consist of antiviral agents and immunotherapy-based approaches. Dendritic cell-based immunotherapy is promising for restoring the T cell-mediated antiviral immune response. Another approach is the specific expansion of the host's pool of HBV-specific T cells. Stimulation of the Toll-like receptors (TLRs), particularly TLR9, provides another means of boosting the antiviral response. Combination therapy with cytokines (interferon gamma and tumor necrosis factor alpha) plus lamivudine is more effective than these agents used alone. Therapeutic vaccines are being developed as an alternative to long-term antiviral treatment or as an adjunct.

Hepatitis B virus genetic mutations and evolution in liver diseases

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus of the Hepadnaviridae family and is approximately 3.2 kb in length. Owing to a lack of proofreading capacity during reverse transcription and a high replication rate, HBV exhibits as quasispecies. To detect the genetic mutations of HBV, many methods with different sensitivities and throughputs were developed. According to documentary records, HBV mutation and evolution were important vial parameters in predicting disease progression and therapeutic outcome. In this review, we separately discussed the correlation between HBV genomic mutations in four open reading frames and liver disease progression. Since some of the results were controversial from different laboratories, it remains to be seen whether functional analyses will confirm their role in modifying the course of infection.