Human Hepatitis B Virus Infection Research Articles

Sodium taurocholate cotransporting polypeptide is a functional receptor for human hepatitis B and D virus.

Human hepatitis B virus (HBV) infection and HBV-related diseases remain a major public health problem. Individuals coinfected with its satellite hepatitis D virus (HDV) have more severe disease. Cellular entry of both viruses is mediated by HBV envelope proteins. The pre-S1 domain of the large envelope protein is a key determinant for receptor(s) binding. However, the identity of the receptor(s) is unknown. Here, by using near zero distance photo-cross-linking and tandem affinity purification, we revealed that the receptor-binding region of pre-S1 specifically interacts with sodium taurocholate cotransporting polypeptide (NTCP), a multiple transmembrane transporter predominantly expressed in the liver. Silencing NTCP inhibited HBV and HDV infection, while exogenous NTCP expression rendered nonsusceptible hepatocarcinoma cells susceptible to these viral infections. Moreover, replacing amino acids 157-165 of nonfunctional monkey NTCP with the human counterpart conferred its ability in supporting both viral infections. Our results demonstrate that NTCP is a functional receptor for HBV and HDV.

Transcriptomic analysis of the woodchuck model of chronic hepatitis B

The Eastern woodchuck (Marmota monax) is naturally infected with woodchuck hepatitis virus (WHV), a hepadnavirus closely related to the human hepatitis B virus (HBV). The woodchuck is used as an animal model for studying chronic hepatitis B (CHB) and HBV-associated hepatocellular carcinoma (HCC) in humans, but the lack of sequence information has hitherto precluded functional genomics analysis. To address this major limitation of the model, we report here the sequencing, assembly, and annotation of the woodchuck transcriptome, together with the generation of custom woodchuck microarrays. Using this new platform, we characterized the transcriptional response to persistent WHV infection and WHV-induced HCC. This revealed that chronic WHV infection, like HBV, is associated with (1) a limited intrahepatic type I interferon response; (2) intrahepatic induction of markers associated with T cell exhaustion; (3) elevated levels of suppressor of cytokine signaling 3 (SOCS3) in the liver; and (4) intrahepatic accumulation of neutrophils. Underscoring the translational value of the woodchuck model, this study also determined that WHV-induced HCC shares molecular characteristics with a subtype of human HCC with poor prognosis. Our data establish the translational value of the woodchuck model and provide new insight into immune pathways which may play a role either in the persistence of HBV infection or the sequelae of CHB.

Differential gene expression analysis of in vitro duck hepatitis B virus infected primary duck hepatocyte cultures

BackgroundThe human hepatitis B virus (HBV), a member of the hepadna viridae, causes acute or chronic hepatitis B, and hepatocellular carcinoma (HCC). The duck hepatitis B virus (DHBV) infection, a dependable and reproducible model for hepadna viral studies, does not result in HCC unlike chronic HBV infection. Information on differential gene expression in DHBV infection might help to compare corresponding changes during HBV infection, and to delineate the reasons for this difference.FindingsA subtractive hybridization cDNA library screening of in vitro DHBV infected, cultured primary duck hepatocytes (PDH) identified cDNAs of 42 up-regulated and 36 down-regulated genes coding for proteins associated with signal transduction, cellular respiration, transcription, translation, ubiquitin/proteasome pathway, apoptosis, and membrane and cytoskeletal organization. Those coding for both novel as well as previously reported proteins in HBV/DHBV infection were present in the library. An inverse modulation of the cDNAs of ten proteins, reported to play role in human HCC, such as that of Y-box binding protein1, Platelet-activating factor acetylhydrolase isoform 1B, ribosomal protein L35a, Ferritin, α-enolase, Acid α-glucosidase and Caspase 3, copper-zinc superoxide dismutase (CuZnSOD), Filamin and Pyruvate dehydrogenase, was also observed in this in vitro study.ConclusionsThe present study identified cDNAs of a number of genes that are differentially modulated in in vitro DHBV infection of primary duck hepatocytes. Further correlation of this differential gene expression in in vivo infection models would be valuable to understand the little known aspects of the hepadnavirus biology.

Sequential control of hepatitis B virus in a mouse model of acute, self-resolving hepatitis B

The determinants of an immune response to the human hepatitis B virus (HBV) are poorly understood. As studies in man and chimpanzees are limited, we aimed at developing a model of self-limiting hepatitis B in mice that helps to dissect the control of HBV by humoral and cellular immune responses. Adenoviral vectors containing 1.3-fold HBV genomes allowed an efficient and reproducible transfer of HBV genomes into mouse livers and initiated HBV replication in mice. HBV transcripts were detected in mouse livers for more than 3 months. HBsAg and HBeAg peaked around day 6 and slowly declined thereafter. A two-phase mild to moderate liver inflammation with elevated serum alanine transaminase activities was observed around day 7 and around day 70 when the vast majority of HBV-specific T cells were detected in the liver. HBV was initially controlled when specific and nonspecific T cells infiltrated the liver and intrahepatic interferon γ levels peaked around day 7, but replicated again from day 10 to day 24 and persisted at low levels thereafter despite the presence of HBV-specific T cells. Finally, HBV replication was terminated after a sufficient B-cell response had been mounted- indicated by anti-HBs seroconversion around day 35. HBV-specific T cells infiltrated the liver a second time around day 70 postinfection. This demonstrates that the established mouse model allows studying the onset and termination of HBV infection and will help to dissect the determinants of HBV control and clearance by the immune response.

A transgenic mouse model for studying HBV infection in neonate

The human hepatitis B virus (HBV) infection is always a worldwide problem, especially the high risk infection of the neonate by chronically HBV infected mother. McGrane et al. [1] have demonstrated that the gene which is driven by the promoter of phosphoenolpyruvate carboxykinase (PEPCK) is mainly expressed in the mouse liver and immediately appears at parturition. We have constructed a transgenic mouse by using PEPCK promoter to drive the pre-S2 and S domain of HBV envelope protein to imitate HBV transmission from mother to child. We want to see whether hepatitis B surface antigen (HBsAg) can persistently exist or be cleared by immune system from the newborn mice.

The C-terminal region of the hepatitis B virus X protein is essential for its stability and function

More than 350 million people worldwide are chronically infected with the human hepatitis B virus (HBV). Chronic HBV infections are associated with the development of hepatocellular carcinoma. While the mechanism of HBV-associated carcinoma remains undefined, it is thought to involve a combination of a continuous inflammatory response to HBV-infected hepatocytes and activities of HBV proteins such as the HBV X protein (HBx). HBx stimulates HBV replication; however, the mechanism by which HBx stimulates HBV replication remains incompletely understood. Studies performed with the woodchuck hepatitis virus (WHV) in woodchucks demonstrated that a C-terminally truncated mutant of the WHV X protein could not stimulate WHV replication. However, whether the C-terminus of HBx is important for HBx-stimulation of HBV replication is unclear. We have constructed C-terminal truncation mutants of HBx and have demonstrated that the C-terminus of HBx impacts HBx stability, HBx activation of transcription, and HBx stimulation of HBV replication. These observations highlight the impact of the HBx C-terminus on HBx activities and the importance of directly analyzing HBx expression and functions in HBV-associated tumors that contain chromosomal integrants of HBV with truncations of the HBx gene.

Focal segmental glomerulosclerosis as a complication of hepatitis B virus infection

Human hepatitis B virus (HBV) is well known as a cause of membranous nephropathy (MN). While the association of HBV infection with MN is strong, data regarding its association with other glomerular diseases are conflicting. Here, we report a case of focal segmental glomerulosclerosis (FSGS) with HBV infection. In this case, we have found HBV-DNA in urinary podocytes by real-time PCR methods. After the administration of anti-viral therapy, FSGS improved, paralleling the decreased level of HBV-DNA in podocytes. The refractory FSGS induced by HBV could be effectively treated with appropriate anti-viral agents.

Analysis of the epitope and neutralizing capacity of human monoclonal antibodies induced by hepatitis B vaccine

Hepatitis B virus (HBV) is an infectious agent that is a significant worldwide public health issue. However, the mechanism by which vaccination-induced antibodies prevent HBV infection remains unclear. To investigate the mechanism by which antibodies induced by hepatitis B surface Ag (HBsAg)-vaccination prevent HBV infection in humans, we prepared human monoclonal antibodies (mAbs) against HBsAg using a novel cell-microarray system from peripheral blood B-lymphocytes from vaccinated individuals. We then characterized the IgG subclass, L-chain subtype, and V-gene repertoire of the H/L-chain, as well as affinities of each of these mAbs. We also determined the epitopes of the individual mAbs using synthesized peptides, and the HBV-neutralizing activities of mAbs using the hepatocyte cell line HepaRG. Consequently, IgG1 and kappa chain was mainly used as the mAbs for HBsAg. Seventy percent of the mAbs bound to the loop domain of the small-HBsAg and showed greater neutralizing activities. There were no relationships between their affinities and neutralization activities. A combination of mAbs recognizing the first loop domain showed a synergistic effect on HBV-neutralizing activity that surpassed conventional hepatitis B-Ig (HBIG) in the HepaRG cell line assay. These results may contribute to the development of effective mAb treatment against HBV infection replacing conventional HBIG administration.

The Hepatitis B Virus X Protein Modulates Hepatocyte Proliferation Pathways To Stimulate Viral Replication

Worldwide, there are over 350 million people who are chronically infected with the human hepatitis B virus (HBV); chronic HBV infections are associated with the development of hepatocellular carcinoma (HCC). The results of various studies suggest that the HBV X protein (HBx) has a role in the development of HBV-associated HCC. HBx can regulate numerous cellular signal transduction pathways, including those that modulate cell proliferation. Many previous studies that analyzed the impact of HBx on cell proliferation pathways were conducted using established or immortalized cell lines, and when HBx was expressed in the absence of HBV replication, and the precise effect of HBx on these pathways has often differed depending on experimental conditions. We have studied the effect of HBx on cell proliferation in cultured primary rat hepatocytes, a biologically relevant system. We demonstrate that HBx, both by itself and in the context of HBV replication, affected the levels and activities of various cell cycle-regulatory proteins to induce normally quiescent hepatocytes to enter the G(1) phase of the cell cycle but not to proceed to S phase. We linked HBx regulation of cell proliferation to cytosolic calcium signaling and HBx stimulation of HBV replication. Cumulatively, our studies suggest that HBx induces normally quiescent hepatocytes to enter the G(1) phase of the cell cycle and that this calcium-dependent HBx activity is required for HBV replication. These studies identify an essential function of HBx during HBV replication and a mechanism that may connect HBV infections to the development of HCC.

Prospective comparison of Abbott RealTime HBV DNA and Versant HBV DNA 3.0 assays for hepatitis B DNA quantitation: Impact on HBV genotype monitoring

The quantitation of human hepatitis B virus (HBV) in the serum of infected patients is recommended to characterize the course of chronic HBV infection. The aim of this prospective study was to evaluate the performance of the Abbott RealTime PCR assay for HBV DNA quantitation by comparison with the standard Versant HBV DNA 3.0 assay. The better sensitivity and broader dynamic range of HBV DNA quantitation using the Abbott RealTime PCR assay was confirmed by the study of 362 serum samples from 311 patients. In addition, data analysis revealed the concordance of HBV DNA quantitations between the two assays . When this evaluation was assessed as a function of HBV genotype, there was discordance for HBV genotype C samples. Thus, we performed an in-house PCR to confirm the discrepancy observed regarding the HBV genotypes. The in-house PCR results agreed better with the Abbott RealTime PCR method when compared with the standard hybridization assay. In conclusion, the wide dynamic range of HBV DNA quantitation achieved with the Abbott RealTime PCR assay makes it appropriate for the clinical monitoring of HBV infected patients. However, a change of HBV DNA quantitation method could influence results on the follow-up of HBV genotype C infected patients.

Immunogenicity in mice and rabbits of DNA vaccines expressing woodchuck hepatitis virus antigens

The licensed vaccine against hepatitis B virus (HBV) is an effective means to prevent infection, but is not an effective therapeutic strategy to treat established chronic infections when used alone. In an animal model of chronic HBV infection (the woodchuck experimentally infected with woodchuck hepatitis virus (WHV)), the combination of conventional vaccine and potent antiviral drugs has shown promise as a potential therapeutic intervention. This approach might be improved further through the application of newer vaccine technologies. In the present study, we evaluated electroporation (EP)-based intramuscular (i.m.) delivery of a codon-optimized DNA vaccine for the WHV surface antigen (WHsAg) in mice and rabbits. In mice, this immunization procedure compared favorably to vaccination by i.m. injection of the DNA vaccine or i.m. administration of a recombinant WHsAg–alum vaccine, exhibiting characteristics expected to be beneficial for a therapeutic vaccine strategy. These included dose efficiency, consistency, vigorous induction of antibody responses to WHsAg, as well as a Th1 bias. Following scale-up to rabbits, a species that approximates the size of the woodchuck, the EP dosing regimen was markedly more effective than conventional i.m. injection of the DNA vaccine. Taken together, these results provide the foundation for studies of EP-based DNA immunization in the woodchuck in order to further assess its potential as an immunotherapeutic approach for treatment of chronic HBV infection in humans.

Prevention of hepatitis B virus infection in vivo by entry inhibitors derived from the large envelope protein

360 million people are chronically infected with the human hepatitis B virus (HBV) and are consequently prone to develop liver cirrhosis and hepatocellular carcinoma. As approved therapeutic regimens-which modulate patients' antiviral defenses or inhibit the viral reverse transcriptase-are generally noncurative, strategies interfering with other HBV replication steps are required. Expanding on our demonstration that acylated peptides derived from the large HBV envelope protein block virus entry in vitro, we show their applicability to prevent HBV or woolly monkey hepatitis B virus infection in vivo, using immunodeficient urokinase-type plasminogen activator (uPA) mice repopulated with primary human or Tupaia belangeri hepatocytes. Accumulation of the peptides in the liver, their extraordinary inhibitory potency and specific mode of action permit subcutaneous delivery at very low doses. Inhibition of hepadnavirus entry thus constitutes a therapeutic approach to prevent primary HBV infection, such as after liver transplantation, and might also restrain virus spread in chronically infected patients.

Antiviral Activity and Hepatoprotection by Heme Oxygenase-1 in Hepatitis B Virus Infection

Induction of heme oxygenase-1 (HO-1) has been shown to be beneficial in immune-mediated liver damage. We now investigate the effects of HO-1 induction in models of human hepatitis B virus (HBV) infection. Adenoviral transfer of an HBV 1.3 genome into wild-type mice was used as a model for acute hepatitis B. HBV transgenic animals were used as a model for chronic HBV infection. HBV replication was assessed by HBV viremia, antigenemia, and Southern blotting, liver damage was assessed by serum alanine aminotransferase activities and histopathology of liver sections. To investigate HO-1 effects on HBV replication at a molecular level, stably HBV-transfected hepatoma cells were used. HBV gene expression, protein stability, transcription, and replication were determined. HO-1 was induced by either cobalt-protoporphyrin-IX or over expressed by adenoviral gene transfer. In the acute hepatitis B model, liver injury was reduced significantly after HO-1 induction. In addition, HO-1 showed a pronounced antiviral effect, which was confirmed in stably HBV-transfected hepatoma cells and in persistently HBV replicating transgenic mice. We showed that HO-1 induction repressed HBV replication directly in hepatocytes at a posttranscriptional step by reducing stability of HBV core protein and thus blocking refill of nuclear HBV covalently closed circular (ccc)DNA. Small interfering RNA directed against HO-1 proved that this effect depended on the expression level of HO-1. Besides its hepatoprotective effect, HO-1 showed a pronounced antiviral activity in HBV infection. Therefore, induction of HO-1 might be a novel therapeutic option for inflammatory flares of hepatitis B.

Recent advances in hepatitis B virus research: A German point of view

More than 30 years after the discovery of human hepatitis B virus (HBV) this virus remains to be one of the major global health problems. In infected adolescents or adults, 5%-10% will lead to a chronic carrier state, whereas in infected neonates up to 90% develop chronicity. It is estimated that about 370 million people are chronic carriers of HBV worldwide. In many regions of the world, chronic HBV infection is still the major cause of liver cirrhosis and hepatocellular carcinoma. During the last 30 years, many steps of the viral life cycle have been unravelled, mainly due to cloning, sequencing and expression of the genomic DNA extracted from HBV virions. This has lead to the development of a safe and efficient vaccine and sensitive tests for HBV surface protein (HBsAg) allowing reliable diagnosis and screening of blood products. More recently, a growing number of reverse transcriptase inhibitors have been developed. However, together with these improvements new deficiencies in prevention and cure of HBV infections are becoming apparent. Although HBV is a DNA virus, it is highly variable under immunity or drug induced selection pressure, resulting in vaccine-related escape mutants and drug resistance. To overcome these challenging problems new antivirals and optimised vaccines have to be developed.

Viral and cellular determinants involved in hepadnaviral entry

Hepadnaviridae is a family of hepatotropic DNA viruses that is divided into the genera orthohepadnavirus of mammals and avihepadnavirus of birds. All members of this family can cause acute and chronic hepatic infection, which in the case of human hepatitis B virus (HBV) constitutes a major global health problem. Although our knowledge about the molecular biology of these highly liver-specific viruses has profoundly increased in the last two decades, the mechanisms of attachment and productive entrance into the differentiated host hepatocytes are still enigmatic. The difficulties in studying hepadnaviral entry were primarily caused by the lack of easily accessible in vitro infection systems. Thus, for more than twenty years, differentiated primary hepatocytes from the respective species were the only in vitro models for both orthohepadnaviruses (e.g. HBV) and avihepadnaviruses (e.g. duck hepatitis B virus [DHBV]). Two important discoveries have been made recently regarding HBV: (1) primary hepatocytes from tree-shrews; i.e., Tupaia belangeri, can be substituted for primary human hepatocytes, and (2) a human hepatoma cell line (HepaRG) was established that gains susceptibility for HBV infection upon induction of differentiation in vitro. A number of potential HBV receptor candidates have been described in the past, but none of them have been confirmed to function as a receptor. For DHBV and probably all other avian hepadnaviruses, carboxypeptidase D (CPD) has been shown to be indispensable for infection, although the exact role of this molecule is still under debate. While still restricted to the use of primary duck hepatocytes (PDH), investigations performed with DHBV provided important general concepts on the first steps of hepadnaviral infection. However, with emerging data obtained from the new HBV infection systems, the hope that DHBV utilizes the same mechanism as HBV only partially held true. Nevertheless, both HBV and DHBV in vitro infection systems will help to: (1) functionally dissect the hepadnaviral entry pathways, (2) perform reverse genetics (e.g. test the fitness of escape mutants), (3) titrate and map neutralizing antibodies, (4) improve current vaccines to combat acute and chronic infections of hepatitis B, and (5) develop entry inhibitors for future clinical applications.

Human Hepatitis B Viral e Antigen Interacts with Cellular Interleukin-1 Receptor Accessory Protein and Triggers Interleukin-1 Response

Human hepatitis B virus (HBV) can cause acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HBV e antigen (HBeAg), a secreted protein and not required for viral replication, is thought to play an immunoregulatory role during viral infection. However, the functional involvement of HBeAg in host immune response has not been fully elucidated. We report in this study that HBeAg can bind to interleukin-1 receptor accessory protein (IL-1RAcP). Interleukin-1 (IL-1) plays an important role in inflammation and regulation of immune response, and membrane form of IL-1RAcP (mIL-1RAcP) is an essential component of trimeric IL-1/IL-1 receptor/mIL-1RAcP complex. We show that glutathione S-transferase- or polyhistidine-tagged recombinant HBeAg can interact with endogenous mIL-1RAcP in vitro. Purified (His)6-HBeAg added in the culture medium can interact with overexpressed FLAG-tagged mIL-1RAcP in vivo. Indirect immunofluorescence and confocal microscopy show that HBeAg colocalizes with mIL-1RAcP on the cell surface. Furthermore, HBeAg is able to induce the interaction of IL-1 receptor I (IL-1RI) with mIL-1RAcP and trigger the recruitment of adaptor protein myeloid differentiation factor 88 (MyD88) to the IL-1RI/mIL-1RAcP complex. Assembly and activation of IL-1RI/mIL-1RAcP signaling complex by HBeAg can activate downstream NF-kappaB pathway through IkappaB degradation, induce NF-kappaB-dependent luciferase expression, and induce the expression of IL-1-responsive genes. Silencing of IL-1RAcP by small interfering RNA dramatically abolishes HBeAg-mediated NF-kappaB activation. These results demonstrate that HBeAg can trigger host IL-1 response by binding to mIL-1RAcP. The interaction of HBeAg with mIL-1RAcP may play an important role in modulating host immune response in acute and chronic HBV infection.

Overexpression of Hepatitis B Virus-binding Protein, Squamous Cell Carcinoma Antigen 1, Extends Retention of Hepatitis B Virus in Mouse Liver

How receptors mediate the entry of hepatitis B virus (HBV) into the target liver cells is poorly understood. Recently, human squamous cell carcinoma antigen 1 (SCCA1) has been found to mediate binding and internalization of HBV to liver-derived cell lines in vitro. In this report, we investigate if SCCA1 is able to function as an HBV receptor and mediate HBV entry into mouse liver. SCCA1 transgene under the control of Rous sarcoma virus promoter was constructed in a minicircle DNA vector that was delivered to NOD/SCID mouse liver using the hydrodynamic technique. Subsequently, HBV-positive human serum was injected intravenously. We demonstrated that approximately 30% of the mouse liver cells expressed a high level of recombined SCCA1 protein for at least 37 d. The HBV surface antigen was found to persist in mouse liver for up to 17 d. Furthermore, HBV genome also persisted in mouse liver, as determined by polymerase chain reaction, for up to 17 d, and in mouse circulation for 7 d. These results suggest that SCAA1 might serve as an HBV receptor or co-receptor and play an important role in mediating HBV entry into hepatocytes, although its role in human HBV infection remains to be determined.

Gene Expression Analysis in HBV Transgenic Mouse Liver: A Model to Study Early Events Related to Hepatocarcinogenesis

Hepatitis B virus (HBV) is one of the major etiological factors responsible for the development of hepatocellular carcinoma (HCC). We used a transgenic mouse, containing HBV sequences, as a model system to unravel the molecular mechanisms of hepatocarcinogenesis induced by HBV. We chose this animal model because it consistently develops liver cancer after intermediate steps that mimic the natural history of HBV infection in humans. In this study, we focus our attention on the early events leading to liver cancer. We compared the gene expression profile of 3-month-old transgenic mice with that of 3-month-old wild-type (wt) animals. In the transgenic mouse, microarray data analysis showed a total of 45 significantly differentially expressed genes, 25 highly expressed (fold change > or =2; P = 0.0025), and 20 downregulated (fold change < or =0.5; P = 0.0025). These genes belong to several different functional categories such as the regulation of immunological response, transcription, intracellular calcium ion mobilization, regulation of cell cycle and proliferation, NF-kappab signal transduction cascades, and apoptosis. In particular, the upregulation of the antiapoptotic gene NuprI and the downregulation of the proapoptotic gene Bnip3 were found. This observation was supported by an in vitro apoptosis assay that showed downregulation of apoptosis in hepatocytes of HBV transgenic mouse compared with wt mice treated with staurosporine. In conclusion, our experimental approach allowed identification of new genes modulated by HBV and showed that the apoptotic process was deregulated in transgenic mouse hepatocytes. These data shed light on one possible mechanism by which HBV induces hepatocarcinogenesis.

Analysis of intrahepatic HBV-specific cytotoxic T-cells during and after acute HBV infection in humans

Characteristics of the intrahepatic virus-specific T-cell response in patients with acute hepatitis B virus (HBV) infection have not been studied due to the risk of complications associated with standard liver biopsies. In this study we aimed to characterize the virus-specific CD8 + T-cell response in the liver of patients with acute HBV infection using fine-needle aspiration-biopsy (FNAB). In HLA-A2 positive patients with acute HBV infection a FNAB was performed at first presentation, at the time of HBsAg-seroconversion and 3 months after HBsAg-seroconversion. HLA-A2 tetramers were used to identify HBV-specific CD8 + T-cells in FNAB-cytology and peripheral blood (PB). At first presentation there was a correlation between the frequency of intrahepatic CD8 + T-cells and the degree of liver damage. At all time points there was sequestering of HBV-specific CD8 + T-cells in the liver, and the percentage of intrahepatic HLA-DR expressing HBV-specific CD8 + T-cells was higher than in PB. Three months after HBsAg-seroconversion the frequency of intrahepatic HBV-specific CD8 + T-cells remained high. HBV-specific CD8 + T-cells are compartmentalized in the liver during acute HBV infection. Their presence in the liver may suggest a role in the resolution of the infection. Intrahepatic HBV-specific CD8 + T cells remain detectable at high frequencies after HBsAg-seroconversion.

P.067 Impact of vaccine-induced HBsAg-specific CD4+ T cells on in vitro hepatitis B-virus infection of primary human hepatocytes

The Eastern woodchuck (Marmota monax) harbors a DNA virus (Woodchuck hepatitis virus [WHV]) that is similar in structure and replicative life cycle to the human hepatitis B virus (HBV). Like HBV, WHV infects the liver and can cause acute and chronic hepatitis. Furthermore, chronic WHV infection in woodchucks usually leads to development of hepatocellular carcinoma (HCC) within the first 2–4 years of life. The woodchuck model has been important in the preclinical evaluation of safety and efficacy of the antiviral drugs now in use for treatment of HBV infection and continues to serve as an important, predictive model for innovative forms of therapy of hepatitis B using antiviral nucleosides and immune response modifiers alone or in combination. Almost all woodchucks that become chronic WHV carriers after experimental neonatal inoculation develop HCC with a median HCC-free survival of 24 months and a median life expectancy of 30–32 months. The woodchuck model of viral-induced HCC has been used effectively for the development of new imaging agents for enhancement of detection of hepatic neoplasms by ultrasound and magnetic resonance imaging. The chemoprevention of HCC using long-term antiviral nucleoside therapy has been shown in the woodchuck, and “proof of principal” has been established for some of the innovative, molecular methods for treatment of HCC. The model is available for fundamental investigations of the viral and molecular mechanisms responsible for hepatocarcinogenesis and should have substantial value for future development of innovative methods for chemoprevention and gene therapy of human HCC.