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Globally, 296 million people are infected with hepatitis B virus (HBV), and approximately one million people die annually from HBV-related causes, including liver cancer. Although there is a preventative vaccine and antiviral therapies suppressing HBV replication, there is no cure. Intensive efforts are under way to develop curative HBV therapies. Currently, only a few biomarkers are available for monitoring or predicting HBV disease progression and treatment response. As new therapies become available, new biomarkers to monitor viral and host responses are urgently needed. In October 2020, the International Coalition to Eliminate Hepatitis B Virus (ICE-HBV) held a virtual and interactive workshop on HBV biomarkers endorsed by the International HBV Meeting. Various stakeholders from academia, clinical practice and the pharmaceutical industry, with complementary expertise, presented and participated in panel discussions. The clinical utility of both classic and emerging viral and immunological serum biomarkers with respect to the course of infection, disease progression, and response to current and emerging treatments was appraised. The latest advances were discussed, and knowledge gaps in understanding and interpretation of HBV biomarkers were identified. This Roadmap summarizes the strengths, weaknesses, opportunities and challenges of HBV biomarkers., (© 2022. Springer Nature Limited.)

Chronic hepatitis B virus (HBV) infection is the leading cause of liver cirrhosis and hepatocellular carcinoma, estimated to be globally responsible for ∼800,000 deaths annually. Although effective vaccines are available to prevent new HBV infection, treatment of existing chronic hepatitis B (CHB) is limited, as the current standard-of-care antiviral drugs can only suppress viral replication without achieving cure. In 2016, the World Health Organization called for the elimination of viral hepatitis as a global public health threat by 2030. The United States and other nations are working to meet this ambitious goal by developing strategies to cure CHB, as well as prevent HBV transmission. This review considers recent research progress in understanding HBV pathobiology and development of therapeutics for the cure of CHB, which is necessary for elimination of hepatitis B by 2030.

Background: An estimated between 257 and 292 million people live with chronic HBV globally. While much is known about the causes, and epidemiology of HBV, little is understood about the quality of life and impact of HBV on those living with the infection., Methods: A random sample of HBV-related email queries sent to the Hepatitis B Foundation, a U.S.-based non-profit organization, over a 12-month period in 2018-2019 were retrieved, tabulated, and analyzed qualitatively to highlight information needs and explore the experiences of people living with HBV and their families and loved ones. Codebook development was informed by the literature and through line-by-line reading of a sub-sample of queries. Data analysis was facilitated by NVivo12 software. Data were coded independently by two members of the research team and intercoder reliability was assessed to assure coding accuracy throughout the coding phase., Results: A total of 338 queries from people around the globe were identified and analyzed. The analysis revealed three thematic groups: 1) health-specific challenges associated with diagnosis and treatment, 2) emotional needs related to experiences with HBV stigma, discrimination, fear, social isolation, and distress and 3) informational needs related to HBV prevention and transmission, and interpretation of laboratory tests., Conclusions: People living with HBV are in need of information to manage their disease and prevent its spread. Analysis of queries uncovered significant misconceptions about HBV transmission and treatment. Additionally, the emotional and psychological impact of an HBV diagnosis on those living with the infection is significant. There is a clear need for patient and community education to expand knowledge and awareness of HBV globally to achieve 2030 WHO HBV elimination goals.

Hepatitis B virus (HBV) mRNA metabolism is dependent upon host proteins PAPD5 and PAPD7 (PAPD5/7). PAPD5/7 are cellular, noncanonical, poly(A) polymerases (PAPs) whose main function is to oligoadenylate the 3' end of noncoding RNA (ncRNA) for exosome degradation. HBV seems to exploit these two ncRNA quality-control factors for viral mRNA stabilization, rather than degradation. RG7834 is a small-molecule compound that binds PAPD5/7 and inhibits HBV gene production in both tissue culture and animal study. We reported that RG7834 was able to destabilize multiple HBV mRNA species, ranging from the 3.5-kb pregenomic/precore mRNAs to the 2.4/2.1-kb hepatitis B virus surface protein (HBs) mRNAs, except for the smallest 0.7-kb X protein (HBx) mRNA. Compound-induced HBV mRNA destabilization was initiated by a shortening of the poly(A) tail, followed by an accelerated degradation process in both the nucleus and cytoplasm. In cells expressing HBV mRNA, both PAPD5/7 were found to be physically associated with the viral RNA, and the polyadenylating activities of PAPD5/7 were susceptible to RG7834 repression in a biochemical assay. Moreover, in PAPD5/7 double-knockout cells, viral transcripts with a regular length of the poly(A) sequence could be initially synthesized but became shortened in hours, suggesting that participation of PAPD5/7 in RNA 3' end processing, either during adenosine oligomerization or afterward, is crucial for RNA stabilization., (Copyright © 2020 American Society for Microbiology.)

Standard literature procedures for the chemical synthesis of l-threose nucleosides generally employ l-ascorbic acid as starting material. Herein, we have explored two alternative routes that start from either l-arabitol or l-diethyl tartrate, both affording 2- O -methyl-l-threofuranose as a key building block for nucleobase incorporation. The access to multigram quantities of this glycosyl donor in a reproducible fashion allows for the preparation of 2'-deoxy-α-l-threofuranosyl phosphonate nucleosides on a large scale. This methodology was applied to the gram scale synthesis of an aryloxy amidate prodrug of phosphonomethoxydeoxythreosyl adenine. This prodrug exerted potent activity against an entecavir-resistant hepatitis B virus (HBV) strain, while leading to a significant reduction in the levels of HBV covalently closed circular DNA in a cellular assay. Furthermore, its remarkable anti-HBV efficacy was also confirmed in vivo using a hydrodynamic injection-based HBV mouse model, without relevant toxicity and systemic exposure occurring.

Similar to other mammalian viruses, the life cycle of hepatitis B virus (HBV) is heavily dependent upon and regulated by cellular (host) functions. These cellular functions can be generally placed in to two categories: (a) intrinsic host restriction factors and innate defenses, which must be evaded or repressed by the virus; and (b) gene products that provide functions necessary for the virus to complete its life cycle. Some of these functions may apply to all viruses, but some may be specific to HBV. In certain cases, the virus may depend upon the host function much more than does the host itself. Knowing which host functions regulate the different steps of a virus' life cycle, can lead to new antiviral targets and help in developing novel treatment strategies, in addition to improving a fundamental understanding of viral pathogenesis. Therefore, in this review we will discuss known host factors which influence key steps of HBV life cycle, and further elucidate therapeutic interventions targeting host-HBV interactions., (Copyright © 2018. Published by Elsevier B.V.)

The discovery in 1965 of the "Australia antigen," subsequently identified as the hepatitis B virus surface antigen (HBsAg), was such a watershed event in virology that it is often thought to mark the beginning of hepatitis research, but it is more accurately seen as a critical breakthrough in a long effort to understand the pathogenesis of infectious hepatitis. A century earlier, Virchow provided an authoritative explanation of "catarrhal jaundice," which did not consider an infectious etiology, but the transmission of jaundice by human serum was clearly identified in two outbreaks in 1885, and the distinction between "infectious" and "serum" hepatitis was recognized by the early 1920s. The inability to culture a virus or reproduce either syndrome in laboratory animals led to numerous studies in human volunteers; by the end of World War II, it was known that the diseases were caused by different filterable agents, and the terms "hepatitis A" and "B" were introduced in 1947 (though some long-incubation cases then designated B must in retrospect have been hepatitis C). The development of a number of liver function tests during the 1950s led to the recognition of anicteric infections and the existence of chronic carriers, but little more could be done until an infectious agent had been identified. Once Blumberg and colleagues had found a specific viral marker, the vast amount of accumulated epidemiologic and clinical data, together with huge numbers of stored serum samples, enabled rapid progress in understanding hepatitis B, and revealed the existence of a vast population of chronically infected people in Asia, Oceania and Africa. In this article, we place the identification of the Australia antigen within the historical context of research on viral hepatitis. Following a chronological review from 1865 to 1965, we summarize how the discovery led to improved safety of blood transfusion, the development of a highly effective vaccine and the eventual identification of the hepatitis C, D and E viruses. This article forms part of a symposium in Antiviral Research on "An unfinished story: from the discovery of the Australia antigen to the development of new curative therapies for chronic hepatitis B.", (Copyright © 2016 Elsevier B.V. All rights reserved.)

Unlabelled: Hepatitis B virus (HBV) is a significant global pathogen, infecting more than 240 million people worldwide. While treatment for HBV has improved, HBV patients often require lifelong therapies and cure is still a challenging goal. Recent advances in technologies and pharmaceutical sciences have heralded a new horizon of innovative therapeutic approaches that are bringing us closer to the possibility of a functional cure of chronic HBV infection. In this article, we review the current state of science in HBV therapy and highlight new and exciting therapeutic strategies spurred by recent scientific advances. Some of these therapies have already entered into clinical phase, and we will likely see more of them moving along the development pipeline., Conclusion: With growing interest in developing and efforts to develop more effective therapies for HBV, the challenging goal of a cure may be well within reach in the near future., (© 2015 by the American Association for the Study of Liver Diseases. This article has been contributed to by U.S. Government employees and their work is in the public domain in the U.S.A.)

Pattern recognition receptor (PRR)-mediated innate immune responses play an essential role in defending the host from viral infections. Intriguingly, hepatitis B virus (HBV) has been shown to induce negligible innate immune responses during the early phase of infection. Whether this is due to the failure of the virus to activate PRRs or suppression of PRR signaling pathways by the virus remains controversial. However, a plethora of evidence suggests that HBV is sensitive to PRR ligand-induced antiviral responses. This review summarizes current understanding of the interaction between HBV and PRR-mediated host innate immunity, antiviral mechanisms of PRR responses against HBV and strategies to combat chronic HBV infection via induction of host innate antiviral responses., (Copyright © 2012 Elsevier B.V. All rights reserved.)

During the course of human immunodeficiency virus type 1 (HIV-1) disease, the virus has been shown to effectively escape the immune response with the subsequent establishment of latent viral reservoirs in specific cell populations within the peripheral blood (PB) and associated lymphoid tissues, bone marrow (BM), brain, and potentially other end organs. HIV-1, along with hepatitis B and C viruses (HBV and HCV), are known to share similar routes of transmission, including intravenous drug use, blood transfusions, sexual intercourse, and perinatal exposure. Substance abuse, including the use of opioids and cocaine, is a significant risk factor for exposure to HIV-1 and the development of acquired immune deficiency syndrome, as well as HBV and HCV exposure, infection, and disease. Thus, coinfection with HIV-1 and HBV or HCV is common and may be impacted by chronic substance abuse during the course of disease. HIV- 1 impacts the natural course of HBV and HCV infection by accelerating the progression of HBV/HCV-associated liver disease toward end-stage cirrhosis and quantitative depletion of the CD4+ T-cell compartment. HBV or HCV coinfection with HIV-1 is also associated with increased mortality when compared to either infection alone. This review focuses on the impact of substance abuse and coinfection with HBV and HCV in the PB, BM, and brain on the HIV-1 pathogenic process as it relates to viral pathogenesis, disease progression, and the associated immune response during the course of this complex interplay. The impact of HIV-1 and substance abuse on hepatitis virus-induced disease is also a focal point.

The high levels of hepatitis B virus (HBV) surface antigen (HBsAg)-bearing subviral particles in the serum of chronically infected individuals play an important role in suppressing HBV-specific immune response and are only mildly affected by the current small molecule therapies. Thus, a therapy that specifically reduces HBsAg serum levels could be used in combination therapy with nucleos(t)ide drugs or permit therapeutic vaccination for the treatment of HBV infection. Herein, we report the design, synthesis, and evaluation of novel triazolo-pyrimidine inhibitors (1, 3, and 4) of HBsAg cellular secretion, with activity against drug-resistant HBV variants. Extensive SAR led to substantial improvements in the EC(50) of the parent compound, 5 (HBF-0259), with the best being 3c, with EC(50) = 1.4 ± 0.4 μM, SI ≥ 36. The lead candidates, both 1a (PBHBV-001) and 3c (PBHBV-2-15), were well-tolerated in both normal and HBV-transgenic mice and exhibited acceptable pharmacokinetics and bioavailability in Sprague-Dawley rats., (© 2011 American Chemical Society)

Background: Hepatitis B virus (HBV) precore G1896A mutation is associated with Hepatitis B e antigen (HBeAg) seroconversion. This mutation and the adjacent G1899A mutation also appear to associate with increased risk of hepatocellular carcinoma. Quantitative mutant dynamics may help determine the potential of these mutants as clinical biomarkers. However, a reliable method to quantify either mutant is not available, partly because the viral genome has polymorphisms in general and the precore mutations are complex., Objectives: (1) To develop a reliable and ultrasensitive assay for the quantification of HBV G1896A and/or G1899A mutants. (2) To obtain preliminary data on the quantities of the precore mutants in patients., Study Design: A SimpleProbe real time PCR assay was developed to quantify the HBV precore mutants. Dual melting analysis and a primer-probe partial overlap approach were used to increase detection accuracy. A wild-type selective PCR blocker was also developed to increase mutant detection sensitivity., Results: The assay correctly identified the precore sequence from all 62 patient samples analyzed. More than 97% of precore sequences in the GenBank can be recognized. Mutant detection sensitivity reached 0.001% using a wild type-selective PCR blocker. At least one precore mutant can be detected from all 20 HBeAg-positive individuals who were negative for precore mutations by DNA sequencing., Conclusions: The reliability of this ultrasensitive mutation quantification assay was demonstrated. The same approaches may be useful for the detection of other clinically significant mutations. Evolution of the precore mutants warrants further studies., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Hepatitis B virus (HBV) carrying the A1762T/G1764A double mutation in the basal core promoter (BCP) region is associated with HBe antigen seroconversion and increased risk of liver cirrhosis and hepatocellular carcinoma (HCC). Quantification of the mutant viruses may help in predicting the risk of HCC. However, the viral genome tends to have nucleotide polymorphism, which makes it difficult to design hybridization-based assays including real-time PCR. Ultrasensitive quantification of the mutant viruses at the early developmental stage is even more challenging, as the mutant is masked by excessive amounts of the wild-type (WT) viruses. In this study, we developed a selective inhibitory PCR (siPCR) using a locked nucleic acid-based PCR blocker to selectively inhibit the amplification of the WT viral DNA but not the mutant DNA. At the end of siPCR, the proportion of the mutant could be increased by about 10,000-fold, making the mutant more readily detectable by downstream applications such as real-time PCR and DNA sequencing. We also describe a primer-probe partial overlap approach which significantly simplified the melting curve patterns and minimized the influence of viral genome polymorphism on assay accuracy. Analysis of 62 patient samples showed a complete match of the melting curve patterns with the sequencing results. More than 97% of HBV BCP sequences in the GenBank database can be correctly identified by the melting curve analysis. The combination of siPCR and the SimpleProbe real-time PCR enabled mutant quantification in the presence of a 100,000-fold excess of the WT DNA.

Analysis of the polypeptide profile in tissues, cells, and sera by high-resolution two-dimensional (2-D) gel electrophoresis offers promise in the identification of biomarkers that correlate with disease. However, sera contain many polypeptides bearing N-linked glycosylation that can complicate interpretation. Therefore, we tested the possibility that de-N-glycosylation of the polypeptides present in human serum would result in a simplification of serum proteome profiles. Briefly, polypeptides present in human serum were left untreated or subjected to de-N-glycosylation by incubation with PNGase F and resolved by high-resolution 2-D gel electrophoresis. De-N-glycosylation reduced the number of glycoform variants, enhanced the resolution of many polypeptides and allowed other polypeptides to become visible. As an initial test of concept, clinically relevant serum samples from individuals with or without diagnosis of hepatocellular carcinoma were compared. Several polypeptides, apparent only after de-N-glycosylation, were shown to correlate with disease. Although the results are preliminary and the identities of all the putative biomarkers not yet known, the data suggest that de-N-glycosylation offers a method to enhance the resolution of serum polypeptide profiles and has value in comparative proteomic studies.

In early 2017, the Hepatitis B Foundation invited 30 experts in the fields of hepatitis B and liver cancer research to identify projects they deemed important to the goal of finding a cure for chronic hepatitis B and D and the diseases with which these viral infections are associated. They were also asked to identify general categories of research and to prioritize sub-project topics within those areas. The experts generally agreed on broadly defined areas of research, but there was usually little difference between the highest and lowest scoring projects; for the most part, all programs described in this document were considered valuable and necessary. An executive summary of this discussion was recently published (Alter et al., Hepatology 2017). The present manuscript reports the areas of research identified by the workshop participants, provides a brief rationale for their selection, and attempts to express differences among the priorities assigned to each area of research, when such distinctions were expressed. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) replicates its DNA genome through reverse transcription of a viral RNA pregenome. We report herein that the interferon (IFN) stimulated exoribonuclease gene of 20 KD (ISG20) inhibits HBV replication through degradation of HBV RNA. ISG20 expression was observed at basal level and was highly upregulated upon IFN treatment in hepatocytes, and knock down of ISG20 resulted in elevation of HBV replication and attenuation of IFN-mediated antiviral effect. The sequence element conferring the susceptibility of HBV RNA to ISG20-mediated RNA degradation was mapped at the HBV RNA terminal redundant region containing epsilon (ε) stem-loop. Furthermore, ISG20-induced HBV RNA degradation relies on its ribonuclease activity, as the enzymatic inactive form ISG20D94G was unable to promote HBV RNA decay. Interestingly, ISG20D94G retained antiviral activity against HBV DNA replication by preventing pgRNA encapsidation, resulting from a consequence of ISG20-ε interaction. This interaction was further characterized by in vitro electrophoretic mobility shift assay (EMSA) and ISG20 was able to bind HBV ε directly in absence of any other cellular proteins, indicating a direct ε RNA binding capability of ISG20; however, cofactor(s) may be required for ISG20 to efficiently degrade ε. In addition, the lower stem portion of ε is the major ISG20 binding site, and the removal of 4 base pairs from the bottom portion of ε abrogated the sensitivity of HBV RNA to ISG20, suggesting that the specificity of ISG20-ε interaction relies on both RNA structure and sequence. Furthermore, the C-terminal Exonuclease III (ExoIII) domain of ISG20 was determined to be responsible for interacting with ε, as the deletion of ExoIII abolished in vitro ISG20-ε binding and intracellular HBV RNA degradation. Taken together, our study sheds light on the underlying mechanisms of IFN-mediated HBV inhibition and the antiviral mechanism of ISG20 in general. [ABSTRACT FROM AUTHOR]

The zinc finger antiviral protein (ZAP) is a mammalian host restriction factor that inhibits the replication of a variety of RNA viruses, including retroviruses, alphaviruses and filoviruses, through interaction with the ZAP-responsive elements (ZRE) in viral RNA, and recruiting the exosome to degrade RNA substrate. Hepatitis B virus (HBV) is a pararetrovirus that replicates its genomic DNA via reverse transcription of a viral pregenomic (pg) RNA precursor. Here, we demonstrate that the two isoforms of human ZAP (hZAP-L and -S) inhibit HBV replication in human hepatocyte-derived cells through posttranscriptional down-regulation of viral pgRNA. Mechanistically, the zinc finger motif-containing N-terminus of hZAP is responsible for the reduction of HBV RNA, and the integrity of the four zinc finger motifs is essential for ZAP to bind to HBV RNA and fulfill its antiviral function. The ZRE sequences conferring the susceptibility of viral RNA to ZAP-mediated RNA decay were mapped to the terminal redundant region (nt 1820–1918) of HBV pgRNA. In agreement with its role as a host restriction factor and as an innate immune mediator for HBV infection, ZAP was upregulated in cultured primary human hepatocytes and hepatocyte-derived cells upon IFN-α treatment or IPS-1 activation, and in the livers of hepatitis B patients during immune active phase. Knock down of ZAP expression increased the level of HBV RNA and partially attenuated the antiviral effect elicited by IPS-1 in cell cultures. In summary, we demonstrated that ZAP is an intrinsic host antiviral factor with activity against HBV through down-regulation of viral RNA, and that ZAP plays a role in the innate control of HBV replication. Our findings thus shed light on virus-host interaction, viral pathogenesis, and antiviral approaches. [ABSTRACT FROM AUTHOR]

Primary cancer of the liver, hepatocellular carcinoma (HCC), is an extremely deadly cancer, with very poor 5 year survivals, following diagnosis. The poor outcomes are believed to be due, in part, to the late times in which the cancers are usually first detected. Improved methods for early detection have thus become a top priority in the management of liver cancer. This Chapter reviews current methods of detection as well as leading new methods. Possible explanations as to why there are so many markers that are being discovered, but so few that make it to validation are discussed. [ABSTRACT FROM AUTHOR]

This review discusses the nature of hepatitis B and C chronicity from a virological perspective. Work described in the literature and our in vitro studies of HBV polypeptide morphogenesis lead us to speculate about a role for HBsAg complex formation in immune evasion that may be especially important during the initial period of infection. Briefly, although viral structural proteins do eventually provide epitopes recognized by the host, we suggest that these HBs Ag complexes, which may themselves be refractory to proteasomal degradation, are an important way by which the virus shields its epitopes and evades early recognition by the cellular immune system. This suggests a central strategy by which the virus has evolved, structurally, to enable the establishment of persistent infection of its host. The concept offers an explanation for the nearly unidirectional and rapid kinetics whereby HBV proteins form multimers and generate a surplus of viral structures that have not been thought to serve any useful structural purpose. [ABSTRACT FROM AUTHOR]

Inhibition of the host RNA polyadenylating polymerases, PAPD5 and PAPD7 (PAPD5/7), with dihydroquinolizinone, a small orally available, molecule, results in a rapid and selective degradation of hepatitis B virus (HBV) RNA, and hence reduction in the amounts of viral gene products. DHQ, is a first in class investigational agent and could represent an entirely new category of HBV antivirals. PAPD5 and PAPD7 are non-canonical, cell specified, polyadenylating polymerases, also called terminal nucleotidyl transferases 4B and 4A (TENT4B/A), respectively. They are involved in the degradation of poor-quality cell transcripts, mostly non-coding RNAs and in the maturation of a sub-set of transcripts. They also appear to play a role in shielding some mRNA from degradation. The results of studies with DHQ, along with other recent findings, provide evidence that repression of the PAPD5/7 arm of the cell "RNA quality control" pathway, causes a profound (multi-fold) reduction rather than increase , in the amount of HBV pre-genomic, pre-core and HBsAg mRNA levels in tissue culture and animal models, as well. In this review we will briefly discuss the need for new HBV therapeutics and provide background about HBV transcription. We also discuss cellular degradation of host transcripts, as it relates to a new family of anti-HBV drugs that interfere with these processes. Finally, since HBV mRNA maturation appears to be selectively sensitive to PAPD5/7 inhibition in hepatocytes, we discuss the possibility of targeting host RNA "quality control" as an antiviral strategy. • Hepatitis B virus RNA maturation uses cellular RNA degradation functions. • Compounds that target host RNA Quality Control may be selectively antiviral. • Poly adenylating Polymerase Domain 5 and 7 polypeptides are important for HBV mRNA maturation. • The host Zinc finger protein ZCHCCH14 is important for HBV mRNA maturation. • HBV mRNA may have structures that make them unusually dependent on host quality control. [ABSTRACT FROM AUTHOR]

Background & Aims: Hepatitis B e antigen (HBeAg) seroconversion is an important clinical and virological “landmark” during chronic hepatitis B virus (HBV) infection. Mutant viruses carrying the precore G1896A and/or the basal core promoter (BCP) A1762T/G1764A mutations are associated with HBeAg seroconversion. However, the exact role of these mutants in HBeAg seroconversion remains unclear, partly because the evolution of these mutant viruses before and after seroconversion has not been well studied. Methods: Using our novel mutant quantification methods, the percentage of the mutant viruses was analyzed both cross-sectionally and longitudinally, before and after seroconversion. Results: Cross-sectional analysis showed that the percentage of both precore and BCP mutants gradually increased with age in the HBeAg-positive population. Follow-up of 18 HBeAg-positive patients revealed that the mutant percentage may stay low and stable for many years, followed by a steady increase in the percentage of G1896A and/or A1762T/G1764A mutants, from <10% to 50–100%, within about 3 years prior to seroconversion. In all cases, increase of mutant percentage was preceded or accompanied by elevated serum alanine aminotransferase. After the seroconversion, the mutant percentage could remain high or decrease significantly, sometimes to below 20%. Conclusions: Levels of G1896A and A1762T/G1764A mutants (of genotypes B and C) in the HBeAg-positive patients may predict the time of HBeAg seroconversion. The dominance of these mutants in the HBeAg-positive phase is more likely the result of immune selection rather than the enhanced replication capability of the mutants. However, anti-HBe antibody may not be a major selection force for these mutants. [Copyright &y& Elsevier]

Abstract: Although alpha interferon (IFN-α) is of benefit in the treatment of viral hepatitis B, HBV replication has been refractory to the cytokine in commonly used hepatocyte-derived cell lines. In search for a cell culture system to study the mechanism by which IFN-α inhibits HBV replication, we infected a variety of cell lines with an adenoviral vector containing a replication competent 1.3-fold genome length HBV DNA (AdHBV) and followed by incubation with IFN-α. We found that IFN-α efficiently decreased the level of HBV DNA replicative intermediates in AdHBV infected Madin–Darby bovine kidney (MDBK) cells. Further analysis revealed, surprisingly, that IFN-α did not directly inhibit HBV replication, rather the amount of adenovirus DNA in the nuclei of MDBK cells was reduced. As a consequence, HBV RNA transcription and DNA replication were inhibited. Experiments with adenoviral vector expressing a green fluorescent protein (GFP) further supported the notion that IFN-α treatment noncytolytically eliminated adenovirus DNA, but did not kill the vector infected MDBK cells. Our data suggest that IFN-α-induced antiviral program is able to discriminate host cellular DNA from episomal viral DNA and might represent a novel pathway of interferon mediate innate defense against DNA virus infections. [Copyright &y& Elsevier]