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Abstract
Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.
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Svicher V, Cento V, Bernassola M, Neumann-Fraune M, Hemert FV, Chen M, Salpini R, Liu C, Longo R, Visca M, Romano S, Micheli V, Bertoli A, Gori C, Ceccherini-Silberstein F, Sarrecchia C, Andreoni M, Angelico M, Ursitti A, Spanò A, Zhang JM, Verheyen J, Cappiello G, Perno CF. Novel HBsAg markers tightly correlate with occult HBV infection and strongly affect HBsAg detection. Antiviral Res 2012; 93:86-93. [DOI: 10.1016/j.antiviral.2011.10.022] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/26/2011] [Accepted: 10/30/2011] [Indexed: 02/06/2023]
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54
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Zhang G, Wang Q, Xu R. Therapeutics Based on microRNA: A New Approach for Liver Cancer. Curr Genomics 2011; 11:311-25. [PMID: 21286309 PMCID: PMC2944997 DOI: 10.2174/138920210791616671] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/11/2010] [Accepted: 04/16/2010] [Indexed: 12/12/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a serious public health hazard. Polygenes involvement, accumulation of genetic and epigenetic changes and immune response of viral vector during gene therapy have resulted in the high mortality rate without marked change. To provide a safeguard for gene therapy and the feasibility for a clinical application, efforts have been focused predominantly upon constructing liver-targeted vector recently. MicroRNAs (miRNAs), a class of short endogenous RNAs, regulate the gene expression at the post-transcriptional level through imperfect base pairing with the 3′-untranslated region of target mRNAs. miRNAs, especially the liver-specific miRNA: miR-122, have multiple functions in liver development and abnormal expression of miRNAs could lead to liver diseases. Altered miRNA expressions have been observed in HCCs, viral hepatitis and hepatic fibrosis. The different expression profiles of miRNAs in HCC suggest that miRNAs may serve as either novel potential targets acting directly as oncogenes or therapeutic molecules working as tumor suppressor genes. Moreover, the abundance in general and liver specificity in particular, all together make them attractive to be considered as elements for hepatic specific targeting viral vector. This review describes recent progress in miRNA investigation on liver associated for better understanding the relationship between miRNA and liver cancer in order to raise prospects for therapy.
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Affiliation(s)
- G Zhang
- Institute of Molecular Medicine, Huaqiao University & Engineering Research Center of Molecular Medicine, Ministry of Education, Quanzhou, Fujian, 362021, China
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55
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Hepatitis B surface antigen: relation to hepatitis B replication parameters in HBeAg-negative chronic hepatitis B. J Hepatol 2011; 55:61-8. [PMID: 21145875 DOI: 10.1016/j.jhep.2010.10.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 09/30/2010] [Accepted: 10/06/2010] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Translation of HBsAg depends on transcription of the appropriate mRNAs from cccDNA, but its relation to other hepatitis B virus (HBV) replication parameters is not known, inasmuch as integrated sequences of HBV-DNA may also contribute to its serum levels, especially in HBeAg-negative chronic hepatitis B (CHB) patients. METHODS We investigated HBsAg serum levels, its hepatocellular expression, and their relationship to HBV replicative- and host-response parameters before treatment in 54 HBeAg-negative CHB patients and in 15 of them after 40.1±33.3months of virological response on oral antiviral (NUC) therapy also. Liver cccDNA and HBV-DNA quantitation, HBsAg- and HBcAg-immunostaining were performed in the same needle biopsy material, while serum HBsAg and HBV-DNA levels were measured in samples drawn on the day of liver biopsy. RESULTS In untreated patients, serum HBsAg correlated positively with HBsAg-positive hepatocytes/mm(2) (p=0.003) and weakly with serum HBV-DNA, but not with cccDNA, liver HBV-DNA, HBcAg-positive hepatocytes/mm(2), or ALT. cccDNA correlated significantly with liver HBV-DNA (p<0.00001), ALT (p=0.001), and serum HBV-DNA levels (p=0.012) but not with liver HBsAg or HBcAg. Antiviral therapy decreased serum HBsAg levels by 79.6% (p=0.012) and liver HBV-DNA by 84.4% (p=0.026) in paired comparisons and, as expected, significantly decreased serum HBV-DNA and ALT levels, but not cccDNA. CONCLUSIONS In untreated HBeAg-negative CHB, serum HBsAg levels reflect liver HBsAg, but not cccDNA or liver HBV-DNA, suggesting that they are not solely dependent on the replicative cycle of HBV. Effective NUC therapy for 3.34 years significantly lowers serum HBsAg and liver HBV-DNA, but not cccDNA.
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56
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Vivekanandan P, Singh OV. Molecular methods in the diagnosis and management of chronic hepatitis B. Expert Rev Mol Diagn 2011; 10:921-35. [PMID: 20964611 DOI: 10.1586/erm.10.75] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chronic hepatitis B (CHB) infection remains a major global problem but the recent advances in molecular methods have revolutionized the diagnosis and management of CHB. Hepatitis B virus (HBV) DNA quantitation is the most useful molecular marker for the diagnosis and management of CHB. There is increasing evidence that the clinical outcome and efficacy of antiviral therapy for CHB could vary with the infecting HBV genotype, core promoter and precore mutations. Early identification of drug resistance is imperative in the management of CHB. The molecular methods for HBV DNA quantitation, HBV genotyping, the identification of mutants, genotypic and phenotypic methods for monitoring drug resistance and their utility and limitations for use in the diagnosis and monitoring of CHB are discussed in this article.
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Affiliation(s)
- Perumal Vivekanandan
- School of Biological Sciences, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India.
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Occult hepatitis B: clinical implications and treatment decisions. Dig Dis Sci 2010; 55:3328-35. [PMID: 20927592 PMCID: PMC3001399 DOI: 10.1007/s10620-010-1413-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 08/26/2010] [Indexed: 01/27/2023]
Abstract
First reported in 1978, occult hepatitis B is a term used to describe the presence of hepatitis B virus (HBV) DNA without hepatitis B surface antigenemia. The prevalence of occult HBV is unclear and depends in part on the sensitivity of the hepatitis B surface antigen (HBsAg) and DNA assays used as well as the prevalence of HBV infection in the study population. The origin of occult HBV also remains in question. Several mechanisms have been hypothesized including mutations in the regulatory regions of the HBV genome, persistence of Ig-bound HBV immune complexes, viral interference, and blockage of free HBsAg secretion. Occult HBV has important clinical implications such as transmission through blood transfusion, reactivation in the setting of immunosuppression, and interference with hepatitis C treatment. To date, there is little data pertaining to the treatment of occult HBV outside of the setting of chemotherapy-induced HBV reactivation.
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58
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Cheung CKY, Lo CM, Man K, Lau GKK. Occult hepatitis B virus infection of donor and recipient origin after liver transplantation despite nucleoside analogue prophylaxis. Liver Transpl 2010; 16:1314-23. [PMID: 21031547 DOI: 10.1002/lt.22169] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Liver grafts from donors positive for antibody to hepatitis B core antigen (anti-HBc) may be used for transplantation in patients with hepatitis B virus (HBV)-related liver disease, and an occult HBV infection may develop from either source. Liver biopsy was performed for 31 patients who remained seronegative for hepatitis B surface antigen for a median of 44.5 months (range = 13.6-126.4 months) and received nucleoside analogue prophylaxis post-transplant. Nineteen of these recipients (61%) had received anti-HBc-positive grafts. Intrahepatic total HBV DNA and covalently closed circular DNA (cccDNA) levels were quantified, and the sequence was analyzed. Intrahepatic total HBV DNA and cccDNA were detectable in 26 (84%) and 16 (52%) of the 31 recipients, respectively, and they were more common when the donor was positive for anti-HBc (95% versus 67%, P = 0.038). The intrahepatic HBV DNA level correlated with the recipient pretransplant serum HBV DNA level (P = 0.06), and the intrahepatic HBV cccDNA level correlated with the donor intrahepatic HBV cccDNA level (P = 0.06). A phylogenetic analysis of the isolated HBV DNA sequence revealed HBV infections of both donor and recipient origins. In conclusion, an occult HBV infection after liver transplantation can originate from both the donor and recipient despite prolonged nucleoside analogue prophylaxis. The presence of intrahepatic HBV cccDNA is attributable more to the persistence of preexisting intrahepatic HBV cccDNA from a donor with previous exposure.
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59
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Reuter S, Oette M, Wilhelm FC, Beggel B, Kaiser R, Balduin M, Schweitzer F, Verheyen J, Adams O, Lengauer T, Fätkenheuer G, Pfister H, Häussinger D. Prevalence and characteristics of hepatitis B and C virus infections in treatment-naïve HIV-infected patients. Med Microbiol Immunol 2010; 200:39-49. [PMID: 20853118 DOI: 10.1007/s00430-010-0172-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Indexed: 02/07/2023]
Abstract
In HIV-infected treatment-naïve patients, we analyzed risk factors for either chronic hepatitis B (HBV) infection, occult HBV infection (OHBV) or a positive hepatitis C (HCV) serostatus. A total of 918 patients of the RESINA-cohort in Germany were included in this study. Before initiating antiretroviral therapy, clinical parameters were collected and blood samples were analyzed for antibodies against HIV, HBV and HCV, HBs antigen and viral nucleic acids for HIV and HBV. Present or past HBV infection (i.e. HBsAg and/or anti-HBc) was found in 43.4% of patients. HBsAg was detected in 4.5% (41/918) and HBV DNA in 6.1% (34/554), resulting in OHBV infection in 2.9% (16/554) of patients. OHBV infection could not be ruled out by the presence of anti-HBs (50.1%) or the absence of all HBV seromarkers (25%). A HCV-positive serostatus was associated with the IVDU transmission route, non-African ethnicity, elevated liver parameters (ASL or GGT) and low HIV viral load. Replicative HBV infection and HCV-positive serostatus both correlated with HIV resistance mutations (P = 0.001 and P = 0.028). HBV and HCV infection are frequent co-infections in HIV treatment-naive patients. These co-infections influence viral evolution, clinical parameters and serological markers. Consequently, HIV patients should routinely be tested for HBV and HCV infection before initiating HIV treatment. OHBV infection constituted almost half of all HBV infections with detectable HBV DNA. Due to a lack of risk factors indicating OHBV infection, HBV diagnosis should not only include serological markers but also the detection of HBV DNA.
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Affiliation(s)
- Stefan Reuter
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, University Hospital, Moorenstr. 5, 40225 Duesseldorf, Germany.
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Abstract
Control of viral replication is a major therapeutic goal to reduce morbidity and mortality from chronic hepatitis B virus (HBV) infection. Recently, methylation has been identified as a novel host defense mechanism, and methylation of viral DNA leads to downregulation of HBV gene expression. To better understand the mechanisms of HBV methylation, cell lines were exposed to HBV using a model system that mimics natural infection and the expression of host DNA methyltransferase genes (DNMTs) was measured. DNMT1, DNMT2, and DNMT3 were all significantly upregulated in response to HBV. DNMT3 was further studied because of its known role in the de novo methylation of DNA. Cotransfection experiments with full-length HBV and DNMT3 led to the downregulation of viral protein and pregenomic RNA production. To investigate whether the upregulation of DNMTs could also have an effect on the methylation of host DNA, cell lines were exposed to HBV in two independent model systems, one that mimics natural infection and a second model with temporary transfection. Host DNA methylation was measured by DNA microarray analysis. Increased methylation of host CpG islands was detected in both experimental systems. Two CpG islands, corresponding to genes SUFU and TIRAP, were selected, and the downregulation of these genes in hepatocellular carcinomas was confirmed. In conclusion, hepatocytes respond to HBV infection by upregulating DNMTs. The DNMTs methylate viral DNA, leading to decreased viral gene expression and decreased viral replication. However, virus-induced overexpression of DNMTs also leads to methylation of host CpG islands.
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Levrero M, Pollicino T, Petersen J, Belloni L, Raimondo G, Dandri M. Control of cccDNA function in hepatitis B virus infection. J Hepatol 2009; 51:581-92. [PMID: 19616338 DOI: 10.1016/j.jhep.2009.05.022] [Citation(s) in RCA: 404] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The template of hepatitis B virus (HBV) transcription, the covalently closed circular DNA (cccDNA), plays a key role in the life cycle of the virus and permits the persistence of infection. Novel molecular techniques have opened new possibilities to investigate the organization and the activity of the cccDNA minichromosome in vivo, and recent advances have started to shed light on the complexity of the mechanisms controlling cccDNA function. Nuclear cccDNA accumulates in hepatocyte nuclei as a stable minichromosome organized by histone and non-histone viral and cellular proteins. Identification of the molecular mechanisms regulating cccDNA stability and its transcriptional activity at the RNA, DNA and epigenetic levels in the course of chronic hepatitis B (CH-B) infection may reveal new potential therapeutic targets for anti-HBV drugs and hence assist in the design of strategies aimed at silencing and eventually depleting the cccDNA reservoir.
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Affiliation(s)
- Massimo Levrero
- Department of Internal Medicine, Sapienza University of Rome, Policlinico Umberto I, 0061 Rome, Italy.
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Vivekanandan P, Thomas D, Torbenson M. Methylation regulates hepatitis B viral protein expression. J Infect Dis 2009; 199:1286-91. [PMID: 19301974 DOI: 10.1086/597614] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Hepatitis B virus (HBV) DNA has been shown to contain CpG islands that are methylated in human tissue, which suggests a role for methylation in regulating viral protein production. However, data are lacking about whether methylation regulates viral gene expression. METHODS To investigate the hypothesis that methylation of viral DNA regulates viral gene expression, unmethylated, partially methylated, and fully methylated viral DNA was transfected into HepG2 cells. In addition, a new assay was designed that specifically identifies methylated covalently closed circular DNA (cccDNA) in human liver tissue. RESULTS Transfection of methylated HBV DNA led to reduced HBV mRNA levels in HepG2 cells, decreased surface and core protein expression in these cells, and decreased secretion of HBV viral proteins into the cell supernatant. These data provide direct evidence that CpG islands regulate gene transcription of HBV. Furthermore, methylated cccDNA was found in tumor and nonneoplastic human liver tissues. Finally, an in vitro equivalent of cccDNA showed decreased viral protein production in HepG2 cells after DNA methylation. CONCLUSION Taken together, these data demonstrate that methylation of viral CpG islands can regulate viral protein production.
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Affiliation(s)
- Perumal Vivekanandan
- Department of Pathology, the Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
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63
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Guo Y, Li Y, Mu S, Zhang J, Yan Z. Evidence that methylation of hepatitis B virus covalently closed circular DNA in liver tissues of patients with chronic hepatitis B modulates HBV replication. J Med Virol 2009; 81:1177-83. [PMID: 19475606 DOI: 10.1002/jmv.21525] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Epigenetic factors may modulate chronic Hepatitis B viral infection by affecting virion gene transcription. The aim of this study was to compare the methylation status of the intrahepatic covalently closed circular DNA (cccDNA) CpG island 2 and HBV replication capability. HBV cccDNA was extracted from liver biopsies of 55 HBsAg-positive patients with chronic hepatitis B (32 HBeAg-positive and 23 HBeAg-negative), and was analyzed for methylation status and quantity. The two Hpa II recognition sequences CCpGG in the CpG island 2 were methylated in infected liver tissues from 24 (43.6%) of 55 patients. Positive ratios of cccDNA methylation were significantly higher in HBeAg-negative patients (15/23, 65.2%) than HBeAg-positive patients (9/32, 28.1%) (P < 0.05). The percentage of methylated-cccDNA/total-cccDNA of HBeAg-negative samples (a median of 48%, ranging from 5% to 83%) was significantly higher (P < 0.001) than HBeAg-positive samples (a median of 14%, ranging from 0.26% to 35%). Ratios of relaxed circular DNA (rcDNA) to cccDNA molecules revealed that cccDNA methylation correlated with impaired virion productivity in HBeAg-positive individuals (P < 0.05). The bisulfite DNA sequencing showed that methylation density was significantly higher in HBeAg-negative than in HBeAg-positive patients (P < 0.05). The methylation level of the CpG island 2 of the cccDNA in HBeAg-negative patients was higher than that in HBeAg-positive patients, suggesting that HBV cccDNA methylation may be relevant to replication capability of HBV.
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Affiliation(s)
- Yanhai Guo
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, China
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64
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Wang N, Zheng Y, Yu X, Lin W, Chen Y, Jiang Q. Sex-modified effect of hepatitis B virus infection on mortality from primary liver cancer. Am J Epidemiol 2009; 169:990-5. [PMID: 19224979 DOI: 10.1093/aje/kwn418] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Sex and hepatitis B virus (HBV) infection are both important risk factors for primary liver cancer. However, their possible biologic interaction has not been well studied. The authors examined data from 89,789 subjects aged 25-69 years who participated in a 14-year cohort study (1992-2006) conducted in Haimen, China. An age-stratified Cox proportional hazards model was used for multivariate analysis. The authors assessed the combined effect of sex and HBV infection on liver cancer mortality by calculating 3 interaction measures: the relative risk due to interaction, the attributable proportion of interaction, and the synergy index. There was a greater risk difference between hepatitis B surface antigen carriers and noncarriers among men than among women. After adjustment for potential confounders, the relative risk due to interaction, the attributable proportion of interaction, and the synergy index were 33.27 (95% confidence interval (CI): 22.54, 43.99), 0.59 (95% CI: 0.55, 0.63), and 2.49 (95% CI: 2.13, 2.90), respectively, suggesting a significant synergistic effect of the interaction between sex and HBV infection on liver cancer mortality. HBV infection had a larger impact on liver cancer mortality in men than in women, which may explain at least part of the sex difference in liver cancer risk.
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Affiliation(s)
- Na Wang
- Department of Epidemiology, Fudan University, Shanghai, People's Republic of China
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