Integrated Hepatitis B Virus DNA Research Articles

DNA methylation at hepatitis B viral integrants is associated with methylation at flanking human genomic sequences.

Integration of DNA viruses into the human genome plays an important role in various types of tumors, including hepatitis B virus (HBV)–related hepatocellular carcinoma. However, the molecular details and clinical impact of HBV integration on either human or HBV epigenomes are unknown. Here, we show that methylation of the integrated HBV DNA is related to the methylation status of the flanking human genome. We developed a next-generation sequencing-based method for structural methylation analysis of integrated viral genomes (denoted G-NaVI). This method is a novel approach that enables enrichment of viral fragments for sequencing using unique baits based on the sequence of the HBV genome. We detected integrated HBV sequences in the genome of the PLC/PRF/5 cell line and found variable levels of methylation within the integrated HBV genomes. Allele-specific methylation analysis revealed that the HBV genome often became significantly methylated when integrated into highly methylated host sites. After integration into unmethylated human genome regions such as promoters, however, the HBV DNA remains unmethylated and may eventually play an important role in tumorigenesis. The observed dynamic changes in DNA methylation of the host and viral genomes may functionally affect the biological behavior of HBV. These findings may impact public health given that millions of people worldwide are carriers of HBV. We also believe our assay will be a powerful tool to increase our understanding of the various types of DNA virus-associated tumorigenesis.

Clonal expansion of hepatocytes with a selective advantage occurs during all stages of chronic hepatitis B virus infection.

Hepatocyte clone size was measured in liver samples of 21 patients in various stages of chronic hepatitis B virus (HBV) infection and from 21 to 76 years of age. Hepatocyte clones containing unique virus-cell DNA junctions formed by the integration of HBV DNA were detected using inverse nested PCR. The maximum hepatocyte clone size tended to increase with age, although there was considerable patient-to-patient variation in each age group. There was an upward trend in maximum clone size with increasing fibrosis, inflammatory activity and with seroconversion from HBV e-antigen (HBeAg)-positive to HBeAg-negative, but these differences did not reach statistical significance. Maximum hepatocyte clone size did not differ between patients with and without a coexisting hepatocellular carcinoma. Thus, large hepatocyte clones containing integrated HBV DNA were detected during all stages of chronic HBV infection. Using laser microdissection, no significant difference in clone size was observed between foci of HBV surface antigen (HBsAg)-positive and HBsAg-negative hepatocytes, suggesting that expression of HBsAg is not a significant factor in clonal expansion. Laser microdissection also revealed that hepatocytes with normal-appearing histology make up a major fraction of the cells undergoing clonal expansion. Thus, preneoplasia does not appear to be a factor in the clonal expansion detected in our assays. Computer simulations suggest that the large hepatocyte clones are not produced by random hepatocyte turnover but have an as-yet-unknown selective advantage that drives increased clonal expansion in the HBV-infected liver.

Hepatitis D and hepatocellular carcinoma.

Hepatitis D virus (HDV) is a defective circular shape single stranded HDV RNA virus with two types of viral proteins, small and large hepatitis D antigens, surrounded by hepatitis B surface antigen. Superinfection with HDV in chronic hepatitis B is associated with a more threatening form of liver disease leading to rapid progression to cirrhosis. In spite of some controversy in the epidemiological studies, HDV infection does increase the risk of hepatocellular carcinoma (HCC) compared to hepatitis B virus (HBV) monoinfection. Hepatic decompensation, rather than development of HCC, is the first usual clinical endpoint during the course of HDV infection. Oxidative stress as a result of severe necroinflammation may progress to HCC. The large hepatitis D antigen is a regulator of various cellular functions and an activator of signal transducer and activator of transcription (STAT)3 and the nuclear factor kappa B pathway. Another proposed epigenetic mechanism by which HCC may form is the aberrant silencing of tumor suppressor genes by DNA Methyltransferases. HDV antigens have also been associated with increased histone H3 acetylation of the clusterin promoter. This enhances the expression of clusterin in infected cells, increasing cell survival potential. Any contribution of HBV DNA integration with chromosomes of infected hepatocytes is not clear at this stage. The targeted inhibition of STAT3 and cyclophilin, and augmentation of peroxisome proliferator-activated receptor γ have a potential therapeutic role in HCC.

Abstract 876: Comprehensive analysis of the complexity of HBV DNA integration sites in the circulation of patients with HBV-related liver disease

Abstract HBV related liver disease ranges from hepatitis, cirrhosis, and hepatocellular carcinoma (HCC), which has a 5-year survival rate of 14% because it is difficult to diagnose at its curative stages. Chronic hepatitis B virus (HBV) infections is the major etiology of HCC, associated with over 50% of HCC cases worldwide and up to 70-80% in endemic areas. 85-90% of HBV related HCCs (HBV-HCC) contain integrated HBV DNA. During chronic HBV infection, HBV DNA has been shown to integrate at random sites in the host chromosome creating a unique genetic signature in each HBV infected hepatocytes. This makes the pool of HBV DNA integration sites highly complex in the liver. This genetic signature in HBV-infected liver along with the fundamental mechanism of carcinogenesis, which is clonal expansion, would result in HCC tissue containing only one to few clonally expanded integration sites, resulting in reduced complexity. Thus, we hypothesize the detection of reduced complexity of HBV DNA integration sites in the circulation can be a potential biomarker for HBV-HCC. In order to study the complexity of cell free circulating HBV DNA integration sites in the circulation, a targeted next generation sequencing (NGS) assay for urine DNA was developed. We chose to use urine in order to avoid detecting of HBV DNA from infectious viruses. Targeted enrichment was performed using an in-solution hybridization platform with biotinylated RNA baits covering the entire HBV genome. The assay was tested using library constructed DNA controls: Hep3B, which contains integrated DNA, and HepG2, which contains no HBV DNA to confirm targeted capture of HBV DNA. Next, matching tissue and urine DNA and DNA from urine collected after surgical removal of HCC tumor from seven HBV-HCC patients were collected and underwent library construction. The library DNA samples were subsequently enriched with HBV and HCC-specific RNA baits. Enriched library DNA was sequenced on Illumina's MiSeq platform. Although the analysis is still ongoing, we have successfully analyzed the complexity of cell-free circulating HBV DNA integration sites in urine. We detected 46 integration sites in the tissue and urine where the location of integrated HBV DNA mapped primarily (89%) to a known HBV integration breakpoint region, HBV DR1-2. Furthermore in 3 HBV-HCC patients, a pattern of reduced complexity of cell-free circulating HBV DNA integration sites was found in urine before the removal of HCC, as compared to urine collected after surgery suggesting reduced complexity of HBV DNA integration sites in HBV-HCC patients. A similar NGS analysis of the urine of hepatitis and cirrhosis patients is in progress. Overall, if successful this study will demonstrate the potential of detecting reduced complexity of HBV DNA integration sites as a biomarker for HBV-HCC screening and provide insight to the involvement of HBV DNA integration sites in HBV-HCC carcinogenesis. Citation Format: Selena Lin, Surbhi Jain, Batbold Boldbaatar, Timothy Block, Wei Song, Ying-Hsiu Su. Comprehensive analysis of the complexity of HBV DNA integration sites in the circulation of patients with HBV-related liver disease. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 876. doi:10.1158/1538-7445.AM2014-876

Do the epidemiology, physiological mechanisms and characteristics of hepatocellular carcinoma in HIV-infected patients justify specific screening policies?

Reducing the incidence of hepatocellular carcinoma (HCC) in HIV-infected patients has become a serious problem when managing these patients. There are many explanations for this disease evolution, which notably include their longer survival under effective antiviral therapy and also the more rapid evolution of chronic liver disease. Despite recent advances in the management of hepatitis B (HBV) and hepatitis C (HCV) viral diseases, which will probably increase the number of patients achieving a virological response, HIV-infected patients with cirrhosis are still at risk of the onset of HCC. This evolution to HCC is also correlated to other comorbidities such as excessive alcohol consumption and nonalcoholic steatohepatitis (NASH). HCC thus remains a public health issue in this population. The poor prognosis and aggressiveness of HCC have been fully demonstrated, but the mechanisms underlying this aggressiveness are not yet well defined. As well as underlying mechanisms that contribute to accelerating hepatocarcinogenesis in HIV-infected patients, there are other reasons why HIV-infected patients should be considered a higher risk population. This review discusses the principal epidemiological determinants; the mechanisms of pathogenesis; and the treatment of HCC in HIV/HBV and HIV/HCV coinfected patients. It also discusses the probable need to develop a specific screening policy for HCC in this population in order to prevent the rapid development and to make them more amenable to a curative treatment.

Infected hematopoietic stem cells and with integrated HBV DNA generate defective T cells in chronic HBV infection patients

A weak T-cell response plays a key role in the persistence of hepatitis B virus (HBV) infection. We aimed to confirm that T-cell defects in patients with chronic HBV infection are associated with HBV DNA infection of bone marrow (BM) hematopoietic stem cells (HSCs). Using reverse transcription polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH), we observed the transcription of HBsAg coding genes and confirmed the integration of HBV DNA in CD34+ BM HSCs from chronic HBV infection patients. T cells were generated by coculturing the HSCs with delta-like ligand 1-expressing OP9 (OP9-DL1) cells. The phenotypes of the T cells were then evaluated by flow cytometric (FACS) analysis on days 14 and 25. The results demonstrated that fewer CD3+TCRaβ+ CD3+CD4+ and CD4+CD8+ T cells were generated from the HSCs of the patients than from the healthy controls, (P < 0.01) but the frequency of CD3+D8+ T cells was not significantly different between the two group (P > 0.05). In contrast, CD4+CD25+ T cells were more in the patient group than in healthy controls (P < 0.01) on both days 14 and 25. There were fewer CD3+CD4+/CD3+CD8+ cells in the patient group than in the healthy control group on day 25 (P < 0.05). Less proliferation and lower levels of IL-2 and IFN- γ were also observed in the patient group compared with the control group (P < 0.05).These data suggest that HBV DNA infected and integrated into the BM HSCs from patients with chronic HBV infection and that these BM HSCs generated defective T cells.

Impact of Occult Hepatitis B Virus Infection or Hepatitis B Virus DNA Integration on Efficacy of Chronic Hepatitis C Treatment With Peginterferon and Ribavirin

Impact of Occult Hepatitis B Virus Infection or Hepatitis B Virus DNA Integration on Efficacy of Chronic Hepatitis C Treatment With Peginterferon and Ribavirin

Role of hepatitis B virus DNA integration in human hepatocarcinogenesis.

Liver cancer ranks sixth in cancer incidence, and is the third leading cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) is the most common type of liver cancer, which arises from hepatocytes and accounts for approximately 70%-85% of cases. Hepatitis B virus (HBV) frequently causes liver inflammation, hepatic damage and subsequent cirrhosis. Integrated viral DNA is found in 85%-90% of HBV-related HCCs. Its presence in tumors from non-cirrhotic livers of children or young adults further supports the role of viral DNA integration in hepatocarcinogenesis. Integration of subgenomic HBV DNA fragments into different locations within the host DNA is a significant feature of chronic HBV infection. Integration has two potential consequences: (1) the host genome becomes altered ("cis" effect); and (2) the HBV genome becomes altered ("trans" effect). The cis effect includes insertional mutagenesis, which can potentially disrupt host gene function or alter host gene regulation. Tumor progression is frequently associated with rearrangement and partial gain or loss of both viral and host sequences. However, the role of integrated HBV DNA in hepatocarcinogenesis remains controversial. Modern technology has provided a new paradigm to further our understanding of disease mechanisms. This review summarizes the role of HBV DNA integration in human carcinogenesis.

Hepatitis B virus-induced hepatocellular carcinoma

Many factors are considered to contribute to hepatitis B virus (HBV) associated hepatocellular carcinoma (HCC), including products of HBV, HBV integration and mutation, and host susceptibility. HBV X protein (HBx) can interfere with several signal pathways that associated with cell proliferation and apoptosis, and the impact of HBx C-terminal truncation in the development of HCC has been implicated. Recent studies by advanced sequencing technologies have revealed recurrent HBV DNA integration sites in hepatoma cells and susceptible genes/SNPs play an important role in the pathogenesis of liver cancer. Epigenetic changes, immune and inflammatory factors are also important contributing factors for liver cancer. This mini-review provides an overview on the recent development of HBV induced HCC.

Re-evaluation of the Carcinogenic Significance of Hepatitis B Virus Integration in Hepatocarcinogenesis

To examine the role of hepatitis B virus (HBV) integration in hepatocarcinogenesis, a systematic comparative study of both tumor and their corresponding non-tumor derived tissue has been conducted in a cohort of 60 HBV associated hepatocellular carcinoma (HCC) patients. By using Alu-polymerase chain reaction (PCR) and ligation-mediated PCR, 233 viral-host junctions mapped across all human chromosomes at random, no difference between tumor and non-tumor tissue was observed, with the exception of fragile sites (P = 0.0070). HBV insertions in close proximity to cancer related genes such as hTERT were found in this study, however overall they were rare events. No direct correlation between chromosome aberrations and the number of HBV integration events was found using a sensitive array-based comparative genomic hybridization (aCGH) assay. However, a positive correlation was observed between the status of several tumor suppressor genes (TP53, RB1, CDNK2A and TP73) and the number of chromosome aberrations (r = 0.6625, P = 0.0003). Examination of the viral genome revealed that 43% of inserts were in the preC/C region and 57% were in the HBV X gene. Strikingly, approximately 24% of the integrations examined had a breakpoint in a short 15 nt viral genome region (1820–1834 nt). As a consequence, all of the confirmed X gene insertions were C-terminal truncated, losing their growth-suppressive domain. However, the same pattern of X gene C-terminal truncation was found in both tumor and non-tumor derived samples. Furthermore, the integrated viral sequences in both groups had a similar low frequency of C1653T, T1753V and A1762T/G1764A mutations. The frequency and patterns of HBV insertions were similar between tumor and their adjacent non-tumor samples indicating that the majority of HBV DNA integration events are not associated with hepatocarcinogenesis.

Identification and extensive analysis of inverted-duplicated HBV integration in a human hepatocellular carcinoma cell line

Hepatitis B virus (HBV) DNA is often integrated into hepatocellular carcinoma (HCC). Although the relationship between HBV integration and HCC development has been widely studied, the role of HBV integration in HCC development is still not completely understood. In the present study, we constructed a pooled BAC library of 9 established cell lines derived from HCC patients with HBV infections. By amplifying viral genes and superpooling of BAC clones, we identified 2 clones harboring integrated HBV DNA. Screening of host-virus junctions by repeated sequencing revealed an HBV DNA integration site on chromosome 11q13 in the SNU-886 cell line. The structure and rearrangement of integrated HBV DNA were extensively analyzed. An inverted duplicated structure, with fusion of at least 2 HBV DNA molecules in opposite orientations, was identified in the region. The gene expression of cancer-related genes increased near the viral integration site in HCC cell line SNU-886.

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.

Clonal Expansion of Normal-Appearing Human Hepatocytes during Chronic Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infections are associated with persistent immune killing of infected hepatocytes. Hepatocytes constitute a largely self-renewing population. Thus, immune killing may exert selective pressure on the population, leading it to evolve in order to survive. A gradual course of hepatocyte evolution toward an HBV-resistant state is suggested by the substantial decline in the fraction of infected hepatocytes that occurs during the course of chronic infections. Consistent with hepatocyte evolution, clones of >1,000 hepatocytes develop postinfection in the noncirrhotic livers of chimpanzees chronically infected with HBV and of woodchucks infected with woodchuck hepatitis virus (W. S. Mason, A. R. Jilbert, and J. Summers, Proc. Natl. Acad. Sci. U. S. A. 102:1139-1144, 2005; W. S. Mason et al., J. Virol. 83:8396-8408, 2009). The present study was carried out to determine (i) if extensive clonal expansion of hepatocytes also occurred in human HBV carriers, particularly in the noncirrhotic liver, and (ii) if clonal expansion included normal-appearing hepatocytes, not just hepatocytes that appear premalignant. Host DNA extracted from fragments of noncancerous liver, collected during surgical resection of hepatocellular carcinoma (HCC), was analyzed by inverse PCR for randomly integrated HBV DNA as a marker of expanding hepatocyte lineages. This analysis detected extensive clonal expansion of hepatocytes, as previously found in chronically infected chimpanzees and woodchucks. Tissue sections were stained with hematoxylin and eosin (H&E), and DNA was extracted from the adjacent section for inverse PCR to detect integrated HBV DNA. This analysis revealed that clonal expansion can occur among normal-appearing human hepatocytes.

DNA double-strand breaks, potential targets for HBV integration

Hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) is one of the most frequently occurring cancers. Hepadnaviral DNA integrations are considered to be essential agents which can promote the process of the hepatocarcinogenesis. More and more researches were designed to find the relationship of the two. In this study, we investigated whether HBV DNA integration occurred at sites of DNA double-strand breaks (DSBs), one of the most detrimental DNA damage. An 18-bp I-SceI homing endonuclease recognition site was introduced into the DNA of HepG2 cell line by stable DNA transfection, then cells were incubated in patients' serum with high HBV DNA copies and at the same time, DSBs were induced by transient expression of I-SceI after transfection of an I-SceI expression vector. By using nest PCR, the viral DNA was detected at the sites of the break. It appeared that integration occurred between part of HBVxgene and the I-SceI induced breaks. The results suggested that DSBs, as the DNA damages, may serve as potential targets for hepadnaviral DNA insertion and the integrants would lead to widespread host genome changes necessarily. It provided a new site to investigate the integration.

To do or not to do: IVF and ICSI in chronic hepatitis B virus carriers

Several assisted reproduction procedures, such as IVF and ICSI, are available for a variety of infertility problems. In fertility clinics, patients are screened for blood-borne viral infections, including hepatitis B virus (HBV). Reasons for screening are prevention of vertical transmission and laboratory safety. We present the case of a 26-year-old female patient with a chronic HBV infection, whose husband tested negative for hepatitis B. She and her husband were referred to our fertility clinic because of subfertility. Analysis of the husband's semen indicated the necessity of an ICSI procedure. The current Dutch guidelines advise against ICSI in chronic HBV carriers, since the risks and effects of chromosomal integration of HBV DNA in the fetus are not well-known. In this article, we review the scientific evidence for the risk of introducing HBV virus into the oocyte and subsequent integration of HBV DNA into the human genome, and debate the question of whether to do, or not to do, IVF and ICSI.

Hepatitis B virus and hepatocellular carcinoma.

Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.

Integration of hepatitis B virus DNA into the myeloid/lymphoid or mixed-lineage leukemia (MLL4) gene and rearrangements of MLL4 in human hepatocellular carcinoma

Integration of hepatitis B virus (HBV) DNA into host DNA is detected in about 90% of HBV-related hepatocellular carcinoma (HCC), but the preferential sites of the viral integration etiologically relevant to oncogenesis have been controversial. By using an adaptor-ligation/suppression-PCR, we identified four integrations into the myeloid/lymphoid or mixed-lineage leukemia 4 (MLL4) gene from 10 HCC patients with positive HBV surface antigen (HBsAg). Determination of the cellular-virus DNA junction demonstrated that various lengths of the virus were integrated within 300 bp of intron 3 flanked by the Alu element of MLL4. Chimeric hepatitis B virus X gene (HBx)/MLL4 transcripts and the HBx fusion proteins were detected. DNA microarray revealed that HBx/MLL4 fusion proteins suppressed unique genes in HepG2 cells. Finally, chromosomal translocations of intron 3 of MLL4 to the specific region of chromosome 17p11.2 in 22 out of 32 HCC patients were observed, showing that the intron 3 region of MLL4 gene would be a target of translocation breakpoint. In conclusion, the present data suggest that the translocation breakpoint of MLL4 gene is one of the preferential targets for HBV DNA integration into the MLL4 gene and the HBV DNA integration may be involved in liver oncogenesis.

COOH-terminal deletion of HBx gene is a frequent event in HBV-associated hepatocellular carcinoma

To investigate the hepatitis B virus (HBV)x gene (HBx) state in the tissues of HBV-related hepatocellular carcinoma (HCC) in Chinese patients and whether there were particular HBx mutations. HBx gene was amplified and direct sequencing was used in genomic DNA samples from 20 HCC and corresponding non-cancerous liver tissues from HBsAg-positive patients. HBV DNA integration and HBx deleted mutation were validated in 45 HCC patients at different stages by Southern blot analysis and polymerase chain reaction methods. The frequencies of HBx point mutations were significantly lower in HCC than their corresponding non-cancerous liver tissues (11/19 vs 18/19, P=0.019). In contrast, deletions in HBx gene were significantly higher in HCC than their non-cancerous liver tissues (16/19 vs 4/19, P<0.001). The deletion of HBx COOH-terminal was detected in 14 HCC tissues. A specific integration of HBx at 17p13 locus was also found in 8 of 16 HCC, and all of them also exhibited full-length HBx deletions. Integrated or integrated coexistence with replicated pattern was obtained in 45.5% (20/45)-56.8% (25/45) tumors and 40.9% (18/45)-52.3% (23/45) non-tumor tissues. HBx deletion, especially the COOH-terminal deletion of HBx is a frequent event in HBV-associated HCC tissues in China. HBV integration had also taken place in partial HCC tissues. This supporting the hypothesis that deletion and probably integrated forms of the HBx gene may be implicated in liver carcinogenesis.

Molecular Pathogenesis of Hepatitis-B-virus-associated Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent and malignant diseases worldwide. Epidemiological studies have clearly demonstrated that chronic hepatitis B virus (HBV) infection is a major etiological factor in the development of HCC. The pathogenesis of HBV-associated HCC has been studied extensively, and the molecular changes associated with malignant transformation have been identified. The predominant carcinogenic mechanisms of HBV-associated HCC are chronic inflammation and the effects of cytokines in the development of fibrosis and liver cell proliferation. An important role is also played by the integration of HBV DNA into host cellular DNA, which disrupts or promotes the expression of cellular genes that are important in cell growth and differentiation. Especially, HBx protein is a transactivating protein that promotes cell growth, survival, and the development of HCC. Continued investigation of the mechanisms underlying hepatocarcinogenesis will refine our current understanding of the molecular and cellular basis for neoplastic transformation in the liver. Prevention of HBV infections and effective treatments for chronic hepatitis B are still needed for the global control of HBV-associated HCC. This review summarizes the current knowledge on the mechanisms involved in HBV-associated hepatocarcinogenesis.

Lamivudine Plus Low-Dose Hepatitis B Immunoglobulin to Prevent Recurrent Hepatitis B Following Liver Transplantation

High-dose intravenous hepatitis B immunoglobulin (HBIG) may prevent recurrent hepatitis B virus (HBV) infection, but the cost has limited its widespread use in countries with endemic HBV infection. We report on long-term safety and efficacy of an alternative strategy of very low doses (400-800 IU/month) of intramuscular (IM) HBIG plus lamivudine. Australian and New Zealand patients who received low-dose HBIG plus lamivudine following liver transplantation for HBV-related end-stage liver disease were studied. Prior to transplantation, patients with detectable serum HBV DNA received lamivudine 100 mg daily. Posttransplantation, all patients received lamivudine 100 mg daily plus IM HBIG 400 or 800 IU daily for 1 week then monthly thereafter. Serum HBV DNA levels were measured prior to lamivudine, at transplantation, and at 12 months posttransplantation. Serum titers of antibody to HBV surface antigen were measured at 1, 3, and 12 months posttransplantation. Between February 1996 and October 2004, 147 patients received low-dose HBIG plus lamivudine. Thirty-one percent were hepatitis B e antigen positive, and 85% were HBV DNA+ prior to transplantation. The median duration of pretransplantation lamivudine was 92 days (range, 1-1775). Median follow-up posttransplantation was 1860 days. Kaplan-Meier patient survival was 92% at 1 year and 88% at 5 years. The actuarial risk of HBV recurrence was 1% at 1 year and 4% at 5 years. Baseline HBV DNA titer was associated with HBV recurrence. Low-dose IM HBIG plus lamivudine provides safe and effective long-term prophylaxis against recurrent HBV at <10% the cost of the high-dose regimen.