Quantitation of HBV covalently closed circular DNA in micro formalin fixed paraffin-embedded liver tissue using rolling circle amplification in combination with real-time PCR. Clin Chim Acta. 2011;412:1905-1911. [PMID: 21741960 DOI: 10.1016/j.cca.2011.06.031]

Hepatocellular carcinoma in a transplanted donor liver and colon cancer developing in a patient with a complex background: A case report

The development of tumors in livers transplanted from hepatitis B virus (HBV)-negative donors to patients with hepatitis B and cirrhosis is rare. The present study describes the case of a woman in her 60s who developed hepatocellular carcinoma (HCC) in her grafted liver, 19 years after transplantation, as well as a metachronous colorectal tumor. The pathological findings, including clinical, immunohistochemical and molecular results, are described in the present case report. The liver tumor was a conventional HCC and the colorectal tumor comprised a tubular adenocarcinoma. Immunohistochemistry of both tumors showed a loss of expression of mutL homolog 1 and postmeiotic segregation increased 2 in the tumor cells, confirming microsatellite instability-high (MSI-H) status. Furthermore, a molecular study detected the presence of genes located on the Y chromosome in the normal and tumor tissues of the liver, proving that the HCC occurred in the grafted liver. The present report also discusses that prolonged use of immunosuppressive drugs to prevent post-transplant rejection, poorly controlled diabetes mellitus and MSI-H may have contributed to the risk of tumor development.

Research progress on detection methods for hepatitis B virus covalently closed circular DNA

Hepatitis B virus (HBV) infection remains a serious global public health problem, and HBV covalently closed circular DNA (cccDNA) in the nucleus of infected cells cannot be eliminated by current treatments and is a major factor in the persistence and recurrence of hepatitis B. Efficient and scientific detection methods are important for clinical monitoring of cccDNA and targeted drug development. Western blotting is the gold standard for the quantitative detection of cccDNA, but it is time-consuming and complex. In recent years, new detection technologies have been continuously updated. There are new developments and breakthroughs in both next-generation polymerase chain reaction (PCR) and non-PCR methods such as in situ hybridization. Some HBV-related markers (such as hepatitis B core-related antigen) have also been shown to be closely related to cccDNA, and they can be used as surrogate markers to indirectly reflect cccDNA content. In this paper, the main detection methods of cccDNA and their improvements are reviewed, the advantages and limitations of these methods are analysed and summarized, and future development directions are proposed.

Characteristics of HBV Novel Serum Markers across Distinct Phases in Treatment-Naïve Chronic HBV-Infected Patients

Background and aims. To investigate the clinical implications of serum HBV RNA, serum hepatitis B core-related antigen (HBcrAg), and quantitative anti-HBc in treatment-naïve patients with chronic HBV infection. Methods. A total of 111 patients in total from different disease phases were recruited, including 21 in immune-tolerant (IT) phase, 49 in immune-clearance (IC) phases, 29 in immune-control or low replicative (LR) phase, and 12 in reactivation phases. Serum HBV RNA, anti-HBc, HBcrAg, and intrahepatic covalently closed circular DNA (cccDNA) were quantified and each of these indicator’s correlation with liver inflammation was analyzed. Results. HBeAg-positive individuals had significant higher serum levels of HBV RNA and HBcrAg than those who were HBeAg negative, similar to that of serum HBV DNA. Comparatively, HBV RNA ( $r$  =0.79, $P<0.01$ ) and HBcrAg ( $r$  =0.78, $P<0.01$ ) had almost same higher overall correlation with the cccDNA, as that of HBV DNA ( $r$  =0.81, $P<0.01$ ). Serum anti-HBc level ( $r$  = -0.52, $P<0.05$ ) is negatively correlated with cccDNA level at IT phase rather than the other three phases. When set the cutoff value at 4.00 log10 IU/mL, serum anti-HBc showed potential to indicate liver inflammation, with AUC as 0.79 and the specificities as 78.85% for HBeAg positive, and with AUC as 0.72 and the specificities as 62.16% for HBeAg-negative patients, respectively. Conclusions. In treatment-naïve patients, levels of serological markers HBV RNA and HBcrAg could mirror intrahepatic cccDNA level, but were not superior to HBV DNA level. Serum anti-HBc level had certain potential to be used as a predicting marker for liver inflammation.

Role of hepatitis B virus in development of hepatocellular carcinoma: Focus on covalently closed circular DNA

Chronic infection with hepatitis B virus (HBV) remains a major global health problem, especially in developing countries. It may lead to prolonged liver damage, fibrosis, cirrhosis, and hepatocellular carcinoma. Persistent chronic HBV infection is related to host immune response and the stability of the covalently closed circular DNA (cccDNA) in human hepatocytes. In addition to being essential for viral transcription and replication, cccDNA is also suspected to play a role in persistent HBV infections or hepatitis relapses since cccDNA is very stable in non-dividing human hepatocytes. Understanding the pathogenicity and oncogenicity of HBV components would be essential in the development of new diagnostic tools and treatment strategies. This review summarizes the role and molecular mechanisms of HBV cccDNA in hepatocyte transformation and hepatocarcinogenesis and current efforts to its detection and targeting.

Prediction for HBsAg seroconversion in children with chronic hepatitis B

Background

To establish a prediction of HBsAg seroconversion in children with chronic hepatitis B (CHB), so as to help clinicians to choose therapeutic strategy.

Methods

A total of 63 children with HBeAg-positive CHB aged 1 to 17 years, who admitted to the fifth medical center of Chinese PLA general hospital and treated with interferon α (IFNα) 48 weeks were enrolled, the clinical data were measured. Based on the results of HBsAg seroconversion (HBsAg < 0.05 IU/mL and anti-HBsAg > 10 IU/L) at week 48, the patients were divided into HBsAg seroconversion (S) group and non-HBsAg seroconversion (NS) group. Multivariate COX regression was used to identify the impact factors associated with HBsAg seroconversion. A novel prediction index was established and the area under the receiver operating characteristic curve (AUROC) was used to assess the prediction for HBsAg seroconversion.

Results

The 63 patients were divided into S group (20.6%, 13/63) and NS group (79.4%, 50/63). Univariate and multivariate analysis identified age, baseline intrahepatic cccDNA and serum HBsAg levels were independent impact factors for HBsAg seroconversion. Intrahepatic cccDNA was positively correlated with serum HBsAg (r = 0.464, p = 0.000). AUROC of HBV cccDNA was 0.83 (95% CI 0.71 to 0.95) and AUROC of baseline HBsAg was 0.77 (95% CI 0.61 to 0.92). Intrahepatic cccDNA ≤ 0.08 log₁₀ copies/10⁶ cell is regarded as cutoff value, the positive predictive value(PPV) and negative predictive value(NPV) for HBsAg seroconversion were 86.8% and 60.0%, respectively, with a sensitivity of 92.0% and specificity of 56.2%. HBsAg ≤ 3.68 log₁₀ IU/mL is used as cut off value, the PPV and NPV for HBsAg seroconversion were 91.2% and 56.3%, respectively; the sensitivity and specificity was 86.0% of 69.2%, respectively. There was no statistical difference between them for predicting HBsAg seroconversion (p = 0.146).

Conclusions

HBsAg seroconversion can be predicted by the baseline serum HBsAg or intrahepatic cccDNA in children with CHB. Using the index, clinicians can choose more reasonable therapeutic strategy and reduce the waste of medical resources.

Briarane-type diterpenoids from a gorgonian coral Ellisella sp. with anti-HBV activities

Chemical investigation of a gorgonian coral Ellisella sp. resulted in the isolation of 12 briarane-type diterpenoids, including eight new congeners namely ellisellolides A-H (1-8). Their structures were determined by extensive spectroscopic analysis, aided the calculated ECD data to support the configurational assignment. All compounds were evaluated for the in vitro anti-HBV activities in HepAD38 cell line, while preliminary analyses of the structure-activity relationship demonstrated that junceellolide C featured an 3E,5(16)-diene and a chlorine-substitution at C-6 is the most active congener. Junceellolide C exhibited efficient reduction against the HBV DNA, HBV RNA and HBeAg production with a dose-dependent manner. It also significantly reduced the HBV cccDNA replenishment and promoted the existed HBV cccDNA degradation. These findings suggest junceellolide C to be a transcription inhibitor of cccDNA and a promising lead for the development of new anti-HBV agent.

Efficacy of a combination of HBV RNA and HBeAg in predicting HBeAg seroconversion in patients treated with entecavir for 144 weeks

BACKGROUND

In some previous studies, serum hepatitis B virus RNA (HBV RNA) was proposed as an HBV viral marker during therapy. However, the dynamic change of HBV RNA, the correlation of HBV RNA with cccDNA, and the combination of HBV RNA with known HBV markers in predicting entecavir (ETV) treatment outcome in the same cohort are rarely reported.

METHODS

A total of 111 HBeAg-positive patients were enrolled in our study. The dynamic changes of serum HBV RNA and the correlation of HBV RNA with other HBV markers were investigated in the early treatment period of 144-week ETV treatment. Intrahepatic cccDNA was detected at baseline and week 48. Receiver operating characteristic analyses were used to identify HBV RNA levels associated with HBeAg seroconversion.

RESULTS

The serum HBV RNA levels decreased more rapidly in patients with HBeAg seroconversion than those without HBeAg seroconversion. The levels of HBV RNA decreased slower compared with the serum HBV DNA, irrespective of whether the patients achieved HBeAg seroconversion or not. Although the serum HBV RNA was positively correlated with cccDNA at baseline among all patients, no significant correlation was observed in the patients with HBeAg seroconversion at week 48 (r=0.094, P=0.588). The area under the receiver operating characteristic (AUROC) of HBV RNA and HBeAg at week 24 was 0.754 and 0.800, respectively. The AUROC of the HBV RNA and HBeAg combination had a higher value (AUROC=0.821).

CONCLUSIONS

The level of HBV RNA at week 24 was a powerful predictor of HBeAg seroconversion in HBeAg-positive patients after 144-week ETV treatment, while the combination of HBV RNA and HBeAg was superior to HBV RNA alone in predicting HBeAg seroconversion.

Junceellolide B, a novel inhibitor of Hepatitis B virus

HBV infection is a common cause of liver disease with a high burden worldwide. Current therapeutic strategy relies on interferon and nucleos(t)ide-type drugs with the limitation of functional cure. In this study, a structure-based screening of marine natural products from an in-house library was performed to hit HBV inhibitors, and the gorgonian-derived briarane-type diterpenoids showed inhibitory effects against HBV DNA replication in HepAD38 cells. Preliminary analyses of structure-activity relationship demonstrated that a briarane-based scaffold with an 3E,5(16)-diene and a chlorine-substitution at C-6 is required for the anti-HBV activity. Junceellolide B is one of the potent HBV inhibitors exhibiting efficient reduction of HBsAg and HBeAg production in HBV infected HepG2-NTCP cells with a dose-dependent manner (p < 0.001). It also significantly reduced the secreted HBV DNA, HBV RNA, and HBeAg in HepAD38 cells with the EC₅₀ values of 0.83, 2.87 and 7.75 μM, respectively. Mechanistically, junceellolide B potently inhibited HBV RNA transcription without promoting HBV RNA degradation. RNA-seq analysis indicated that junceellolide B significantly decreased HBV cccDNA-transcripted products accompanying stable down-regulation of the expression of RNA polymerase II related host transcription factors (ZBED6 and ZBTB7B). These findings suggest junceellolide B to be a transcription inhibitor of cccDNA and a promising lead for the development of new anti-HBV agent.

Exonuclease I and III improve the detection efficacy of hepatitis B virus covalently closed circular DNA

BACKGROUND

Hepatitis B virus covalently closed circular DNA (HBV cccDNA) is an important biomarker of hepatitis B virus infection. However, the current methods are not specific and sensitive. The present study aimed to develop a specific and sensitive assay method for the quantification of HBV cccDNA.

METHODS

Exonuclease I (Exo I) & Exonuclease III (Exo III) and specific primer probes are used in real-time PCR. The virus particles isolated from peripheral blood mononuclear cells were used as negative control and HBV1.3 recombinant plasmid 3.2 kb circular DNA fragment was used as positive control. The methods of cccDNA detection were evaluated in cell lines, plasmid, animal model, patient serum and liver biopsies.

RESULTS

A linear range of 10¹-10⁷ copies/assay using specific primers for HBV cccDNA was established. HBV cccDNA were only detected in cell lines, animal model and liver tissue. It cannot be detected in serum samples. Intrahepatic HBV cccDNA level had good correlation with intrahepatic total HBV DNA level (r = 0.765, P < 0.001).

CONCLUSIONS

The real-time quantitative PCR is an effective and feasible method for sensitive and specific detection of low copy number of cccDNA. The novel detection method is fast, provides high sensitivity and specificity and can be used in clinical practice.

Mapping the Interactions of HBV cccDNA with Host Factors

Hepatitis B virus (HBV) infection is a major health problem affecting about 300 million people globally. Although successful administration of a prophylactic vaccine has reduced new infections, a cure for chronic hepatitis B (CHB) is still unavailable. Current anti-HBV therapies slow down disease progression but are not curative as they cannot eliminate or permanently silence HBV covalently closed circular DNA (cccDNA). The cccDNA minichromosome persists in the nuclei of infected hepatocytes where it forms the template for all viral transcription. Interactions between host factors and cccDNA are crucial for its formation, stability, and transcriptional activity. Here, we summarize the reported interactions between HBV cccDNA and various host factors and their implications on HBV replication. While the virus hijacks certain cellular processes to complete its life cycle, there are also host factors that restrict HBV infection. Therefore, we review both positive and negative regulation of HBV cccDNA by host factors and the use of small molecule drugs or sequence-specific nucleases to target these interactions or cccDNA directly. We also discuss several reporter-based surrogate systems that mimic cccDNA biology which can be used for drug library screening of cccDNA-targeting compounds as well as identification of cccDNA-related targets.

A two-step lineage reprogramming strategy to generate functionally competent human hepatocytes from fibroblasts

Terminally differentiated cells can be generated by lineage reprogramming, which is, however, hindered by incomplete conversion with residual initial cell identity and partial functionality. Here, we demonstrate a new reprogramming strategy by mimicking the natural regeneration route, which permits generating expandable hepatic progenitor cells and functionally competent human hepatocytes. Fibroblasts were first induced into human hepatic progenitor-like cells (hHPLCs), which could robustly expand in vitro and efficiently engraft in vivo. Moreover, hHPLCs could be efficiently induced into mature human hepatocytes (hiHeps) in vitro, whose molecular identity highly resembles primary human hepatocytes (PHHs). Most importantly, hiHeps could be generated in large quantity and were functionally competent to replace PHHs for drug-metabolism estimation, toxicity prediction and hepatitis B virus infection modeling. Our results highlight the advantages of the progenitor stage for successful lineage reprogramming. This strategy is promising for generating other mature human cell types by lineage reprogramming.

The preS deletion of hepatitis B virus (HBV) is associated with liver fibrosis progression in patients with chronic HBV infection

BACKGROUND AND AIMS

Limited data are available regarding the association of hepatitis B virus (HBV) mutations with liver fibrosis in HBV infection. The study aimed to clarify whether HBV preS deletion mutation is associated with liver fibrosis progression.

METHODS

A total of 469 patients were enrolled, including 324 with chronic hepatitis B (CHB), 28 with HBV-related compensated liver cirrhosis (LC), and 117 with HBV-related decompensated LC. All CHB and compensated LC patients received liver biopsy. Fibrosis grade was assessed using METAVIR score. HBV preS deletion was determined by direct sequencing and verified by clonal sequencing.

RESULTS

Overall preS deletion was detected in 12.6% (59/469) patients, specifically, in 7.51% (13/173), 10.60% (16/151), and 20.69% (30/145) of patients with no-to-mild liver fibrosis (F0-1), moderate-to-severe liver fibrosis (F2-3), and cirrhosis (F4), respectively (p < 0.01). Patients with preS-deleted HBV had lower serum HBV DNA and albumin levels compared to patients with wild-type HBV. The median length of preS deletion was 39-base pairs (bp) (3-204 bp) and the deletion most frequently emerged in preS2 initial region. Multivariate analysis identified the preS2 deletion rather than preS1 deletion to be an independent risk factor of significant fibrosis, i.e., METAVIR F ≥ 2 (p = 0.007). In addition, preS-deleted viral sequences were detected in the pool of intrahepatic HBV covalently closed circular DNA.

CONCLUSIONS

HBV preS deletion is positively associated with liver fibrosis progression in chronic HBV-infected patients. HBV preS2 deletion may serve as a warning indicator for liver fibrosis progression.

The gRNA-miRNA-gRNA Ternary Cassette Combining CRISPR/Cas9 with RNAi Approach Strongly Inhibits Hepatitis B Virus Replication

The CRISPR/Cas9 system is a novel genome editing technology which has been successfully used to inhibit HBV replication. Here, we described a novel gRNA-microRNA (miRNA)-gRNA ternary cassette driven by a single U6 promoter. With an anti-HBV pri-miR31 mimic integrated between two HBV-specific gRNAs, both gRNAs could be separated from the long transcript of gRNA-miR-HBV-gRNA ternary cassette through Drosha/DGCR8 processing. The results showed that the gRNA-miR-HBV-gRNA ternary cassette could efficiently express two gRNAs and miR-HBV. The optimal length of pri-miRNA flanking sequence in our ternary cassette was determined to be 38 base pairs (bp). Besides, HBV-specific gRNAs and miR-HBV in gRNA-miR-HBV-gRNA ternary cassette could exert a synergistic effect in inhibiting HBV replication and destroying HBV genome in vitro and in vivo. Most importantly, together with RNA interference (RNAi) approach, the HBV-specific gRNAs showed the potent activity on the destruction of HBV covalently closed circular DNA (cccDNA). Since HBV cccDNA is an obstacle for the elimination of chronic HBV infection, the gRNA-miR-HBV-gRNA ternary cassette may be a potential tool for the clearance of HBV cccDNA.

Detection of HBV Covalently Closed Circular DNA

Chronic hepatitis B virus (HBV) infection affects approximately 240 million people worldwide and remains a serious public health concern because its complete cure is impossible with current treatments. Covalently closed circular DNA (cccDNA) in the nucleus of infected cells cannot be eliminated by present therapeutics and may result in persistence and relapse. Drug development targeting cccDNA formation and maintenance is hindered by the lack of efficient cccDNA models and reliable cccDNA detection methods. Southern blotting is regarded as the gold standard for quantitative cccDNA detection, but it is complicated and not suitable for high-throughput drug screening, so more sensitive and simple methods, including polymerase chain reaction (PCR)-based methods, Invader assays, in situ hybridization and surrogates, have been developed for cccDNA detection. However, most methods are not reliable enough, and there are no unified standards for these approaches. This review will summarize available methods for cccDNA detection. It is hoped that more robust methods for cccDNA monitoring will be developed and that standard operation procedures for routine cccDNA detection in scientific research and clinical monitoring will be established.

A new model mimicking persistent HBV e antigen-negative infection using covalently closed circular DNA in immunocompetent mice

Despite the availability of an effective vaccine, hepatitis B virus (HBV) infection remains a major health problem. HBV e antigen (HBeAg)-negative strains have become prevalent. Previously, no animal model mimicked the clinical course of HBeAg-negative HBV infection. To establish an HBeAg-negative HBV infection model, the 3.2-kb full-length genome of HBeAg-negative HBV was cloned from a clinical sample and then circularized to form covalently closed circular (cccDNA). The resulting cccDNA was introduced into the liver of C57BL/6J mice through hydrodynamic injection. Persistence of the HBeAg-negative infection was monitored at predetermined time points using HBV-specific markers including HBV surface antigen (HBsAg), HBeAg, and HBV core antigen (HBcAg) as well as DNA copies. Throughout the study, pAAV-HBV1.2 was used as a control. In mice injected with HBeAg-negative cccDNA, the HBV infection rate was 100% at the initial stage. HBsAg levels increased up to 1 week, at which point levels peaked and dropped quickly thereafter. In 60% of injected mice, HBsAg and HBcAg persisted for more than 10 weeks. High numbers of HBV DNA copies were detected in the serum and liver. Moreover, cccDNA persisted in the liver tissue of HBeAg-negative mice. In contrast to the pAAV-HBV 1.2 injected mice, no HBeAg was found in mice injected with HBeAg-negative HBV throughout the study period. These results demonstrate the first successful establishment of a model of HBeAg-negative HBV-persistent infection in immunocompetent mice. Compared to pAAV-HBV1.2-injected mice, the infection persistence and levels of serum virological and biochemical markers were approximately equal in the model mice. This model will be useful for mechanistic studies on HBeAg-negative HBV infection and will facilitate the evaluation of new antiviral drugs.

Removal of Integrated Hepatitis B Virus DNA Using CRISPR-Cas9

The presence of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) and the permanent integration of HBV DNA into the host genome confers the risk of viral reactivation and hepatocellular carcinoma. Nucleoside/nucleotide analogs alone have little or no capacity to eliminate replicative HBV templates consisting of cccDNA or integrated HBV DNA. Recently, CRISPR/Cas9 technology has been widely applied as a promising genome-editing tool, and HBV-specific CRISPR-Cas9 systems were shown to effectively mediate HBV cccDNA disruption. However, the integrated HBV DNA fragments are considered as important pro-oncogenic properties and it serves as an important template for viral replication and expression in stable HBV cell line. In this study, we completely excised a full-length 3,175-bp integrated HBV DNA fragment and disrupted HBV cccDNA in a stable HBV cell line. In HBV-excised cell line, the HBV cccDNA inside cells, supernatant HBV DNA, HBsAg, and HBeAg remained below the negative critical values for more than 10 months. Besides, by whole genome sequencing, we analyzed off-target effects and excluded cell contamination. It is the first time that the HBV infection has been fully eradicated in a stable HBV cell line. These findings demonstrate that the CRISPR-Cas9 system is a potentially powerful tool capable of promoting a radical or “sterile” HBV cure.

Serum hepatitis B core-related antigen is a satisfactory surrogate marker of intrahepatic covalently closed circular DNA in chronic hepatitis B

Recently, hepatitis B core-related antigen (HBcrAg) has been suggested as an additional marker of hepatitis B virus (HBV) infection. This study aimed to investigate whether serum quantitative HBcrAg (qHBcrAg) was a satisfactory surrogate marker of intrahepatic covalently closed circular DNA (cccDNA). A total of 139 patients with liver biopsy were enrolled, consisting of 59 patients in immune tolerance (IT) phase, 52 patients in immune clearance (IC) phase, 18 patients in low-replication (LR) phase, and 10 patients in reactivation phase. All patients in IC phase have received entecavir (ETV) therapy, and 32 of them undergone a second liver biopsy at 24 months. Among those patients, qHBcrAg was strongly correlated with intrahepatic cccDNA, which is superior to that of qHBsAg and HBV DNA. And similar findings were also observed in patients in IT, IC, LR and reactivation phases. Among the 32 ETV-treated patients with a second liver biopsy in IC phase, the decline of intrahepatic cccDNA was accompanied by changes in both qHBcrAg and qHBsAg. However, as compared to qHBsAg, the change of qHBcrAg was more strongly associated with intrahepatic cccDNA-decline. In summary, serum qHBcrAg should be a satisfactory surrogate of intrahepatic HBV cccDNA in CHB patients.

Quantitative intrahepatic HBV cccDNA correlates with histological liver inflammation in chronic hepatitis B virus infection

BACKGROUND

The aim of this study was to determine the role of baseline hepatitis B virus (HBV) forming covalently closed circular DNA (HBV cccDNA) in liver inflammation in patients infected with HBV with serum alanine aminotransferase (ALT) levels under two times the upper limit of normal (2×ULN).

METHODS

After liver biopsy and serum virological and biochemical marker screening, patients diagnosed with chronic HBV infection with serum ALT levels under 2×ULN and histological liver inflammation of less than grade G2 were prospectively recruited into this study. Recruitment took place between March 2009 and November 2010 at the Center of Infectious Disease, Sichuan University. Patient virological and biochemical markers, as well as markers of liver inflammation, were monitored.

RESULTS

A total of 102 patients were recruited and 68 met the inclusion criteria; the median follow-up was 4.1 years (range 3.9-5.2 years). During follow-up, 41 patients (60.3%) exhibited signs of inflammation. Baseline HBV cccDNA >1 copy/cell (odds ratio 9.43, p=0.049) and liver inflammation grade ≥G1 (odds ratio 5.77, p=0.046) were both independent predictors of liver inflammation.

CONCLUSIONS

A higher baseline intrahepatic HBV cccDNA level may increase the risk of liver inflammation. Further investigations will be required to validate HBV cccDNA as an intrahepatic virological marker of patients who require extended outpatient management.

An Effective Molecular Target Site in Hepatitis B Virus S Gene for Cas9 Cleavage and Mutational Inactivation

Chronic hepatitis B infection remains incurable because HBV cccDNA can persist indefinitely in patients recovering from acute HBV infection. Given the incidence of HBV infection and the shortcomings of current therapeutic options, a novel antiviral strategy is urgently needed. To inactivate HBV replication and destroy the HBV genome, we employed genome editing tool CRISPR/Cas9. Specifically, we found a CRISPR/Cas9 system (gRNA-S4) that effectively targeted the HBsAg region and could suppress efficiently viral replication with minimal off-target effects and impact on cell viability. The mutation mediated by CRISPR/Cas9 in HBV DNA both in a stable HBV-producing cell line and in HBV transgenic mice had been confirmed and evaluated using deep sequencing. In addition, we demonstrated the reduction of HBV replication was caused by the mutation of S4 site through three S4 region-mutated monoclonal cells. Besides, the gRNA-S4 system could also reduce serum surface-antigen levels by 99.91 ± 0.05% and lowered serum HBV DNA level below the negative threshold in the HBV hydrodynamics mouse model. Together, these findings indicate that the S4 region may be an ideal target for the development of innovative therapies against HBV infection using CRISPR/Cas9.

PreS deletion profiles of hepatitis B virus (HBV) are associated with clinical presentations of chronic HBV infection

BACKGROUND

The association of hepatitis B virus (HBV) preS1 and preS2 deletions with progressive liver diseases are not fully understood.

OBJECTIVE

The study aimed to investigate characteristics of HBV preS deletion in HBV-infected patients with different illness categories.

STUDY DESIGN

Total of 539 HBV-infected patients were enrolled in the study, including 146 with chronic hepatitis B (CHB), 111 with HBV-related liver cirrhosis (LC), 146 with HBV-related acute-on-chronic liver failure (ACLF), and 136 with HBV-related hepatocellular carcinoma (HCC). PreS deletion was determined by sequencing. Replicons containing representative preS1 and preS2 deletion mutants and wild-type were respectively constructed and transfected into HepG2 cells for phenotypic analysis.

RESULTS

The detection rates of overall preS deletion were 15.8%, 26.1%, 24.0%, and 34.6% in CHB, LC, ACLF, and HCC patients, respectively. PreS1 deletion was most frequently detected in LC patients while preS2 deletion was most frequently detected in HCC patients, both frequencies were significantly higher than that in CHB patients (17.1% vs. 4.8%, P<0.01; 19.1% vs. 4.8%, P<0.01). The deletion patterns across preS gene were different among the 4 illness categories. Compared with wild-type strain, the preS1 deletion mutant had defected preS1 expression, significantly decreased viral mRNA level and SP II promoter activity; while preS2 deletion mutant had defected preS2 expression, and significantly decreased viral mRNA level.

CONCLUSIONS

HBV preS deletion was associated with advancement of liver diseases not only presented in preS deletion incidence, but also in the deletion pattern. Patients with preS2 deletion might have a higher risk to develop HCC.

Attacking hepatitis B virus cccDNA--The holy grail to hepatitis B cure

HBV deposits a covalently closed circular DNA form, called cccDNA, in the nucleus of infected cells. As the central transcription template, the cccDNA minichromosome is a key intermediate in the HBV life cycle. Its location in the nucleus makes cccDNA a difficult target for antivirals and immune response, and therefore it is responsible for chronicity of HBV infection. While little is known about the mechanisms involved in cccDNA formation, current research is accumulating data on the mechanisms regulating transcription from cccDNA, and the first potential targeting approaches have been reported. This review will summarize our knowledge about cccDNA biology and the latest advances in cccDNA targeting strategies in order to finally achieve an HBV cure.

Detection of Hepatitis B Virus Covalently Closed Circular DNA in the Plasma of Iranian HBeAg-Negative Patients With Chronic Hepatitis B

BACKGROUND

Covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is a marker of HBV replication in the liver of patients infected with HBV.

OBJECTIVES

This study aimed to investigate the association between the presence of cccDNA in the plasma samples of Iranian treatment-naive patients with chronic hepatitis B infection and HBV viral load and HBsAg levels.

PATIENTS AND METHODS

From April 2012 to May 2015, 106 treatment-naive patients with chronic hepatitis B infection were enrolled in this cross-sectional study. The HBsAg titer was measured by the Roche HBsAg II assay on the Cobas e411 system, and HBV DNA quantitation was performed using the COBAS TaqMan 48 kit. Real-time polymerase chain reaction was performed for the detection of HBV cccDNA.

RESULTS

The mean (SD) age of the patients was 41.1 ± 12.4 years (range, 20 - 62 years). From a total of 106 study participants, 67 (63.2%) were males. The HBV cccDNA was detected in plasma specimens in 19 (17.9%) out of the total 106 patients, and a significant relationship was found between the presence of cccDNA in plasma sample of males (23.9%) and females (7.7%) (P = 0.039). Also, a significant correlation was found between the presence of cccDNA in plasma sample of the patients and HBV viral load level (P < 0.0001) and HBsAg titer (P = 0.0043).

CONCLUSIONS

This study showed that cccDNA can be detected in the plasma specimen of 17.9% of Iranian treatment-naive patients with chronic hepatitis B infection. Therefore, designing prospective studies focusing on the detection of cccDNA in these patients would provide more information.

Dual gRNAs guided CRISPR/Cas9 system inhibits hepatitis B virus replication

AIM

To screen and investigate the effective gRNAs against hepatitis B virus (HBV) of genotypes A-D.

METHODS

A total of 15 gRNAs against HBV of genotypes A-D were designed. Eleven combinations of two above gRNAs (dual-gRNAs) covering the regulatory region of HBV were chosen. The efficiency of each gRNA and 11 dual-gRNAs on the suppression of HBV (genotypes A-D) replication was examined by the measurement of HBV surface antigen (HBsAg) or e antigen (HBeAg) in the culture supernatant. The destruction of HBV-expressing vector was examined in HuH7 cells co-transfected with dual-gRNAs and HBV-expressing vector using polymerase chain reaction (PCR) and sequencing method, and the destruction of cccDNA was examined in HepAD38 cells using KCl precipitation, plasmid-safe ATP-dependent DNase (PSAD) digestion, rolling circle amplification and quantitative PCR combined method. The cytotoxicity of these gRNAs was assessed by a mitochondrial tetrazolium assay.

RESULTS

All of gRNAs could significantly reduce HBsAg or HBeAg production in the culture supernatant, which was dependent on the region in which gRNA against. All of dual gRNAs could efficiently suppress HBsAg and/or HBeAg production for HBV of genotypes A-D, and the efficacy of dual gRNAs in suppressing HBsAg and/or HBeAg production was significantly increased when compared to the single gRNA used alone. Furthermore, by PCR direct sequencing we confirmed that these dual gRNAs could specifically destroy HBV expressing template by removing the fragment between the cleavage sites of the two used gRNAs. Most importantly, gRNA-5 and gRNA-12 combination not only could efficiently suppressing HBsAg and/or HBeAg production, but also destroy the cccDNA reservoirs in HepAD38 cells.

CONCLUSION

These results suggested that CRISPR/Cas9 system could efficiently destroy HBV expressing templates (genotypes A-D) without apparent cytotoxicity. It may be a potential approach for eradication of persistent HBV cccDNA in chronic HBV infection patients.

MitoRCA-seq reveals unbalanced cytocine to thymine transition in Polg mutant mice

Mutations in mitochondrial DNA (mtDNA) can lead to a wide range of human diseases. We have developed a deep sequencing strategy, mitoRCA-seq, to detect low-frequency mtDNA point mutations starting with as little as 1 ng of total DNA. It employs rolling circle amplification, which enriches the full-length circular mtDNA by either custom mtDNA-specific primers or a commercial kit, and minimizes the contamination of nuclear encoded mitochondrial DNA (Numts). By analyzing the mutation profiles of wild-type and Polg (mitochondrial DNA polymerase γ) mutant mice, we found that mice with the proofreading deficient mtDNA polymerase have a significantly higher mutation load by expanding the number of mutation sites and to a lesser extent by elevating the mutation frequency at existing sites even before the premature aging phenotypes appear. Strikingly, cytocine (C) to thymine (T) transitions are found to be overrepresented in the mtDNA of Polg mutated mice. The C → T transition, compared to other types of mutations, tends to increase the hydrophobicity of the underlying amino acids, and may contribute to the impaired protein function of the Polg mutant mice. Taken together, our findings may provide clues to further investigate the molecular mechanism underlying premature aging phenotype in Polg mutant mice.

Occult hepatitis B virus infection predicts de novo hepatitis B infection in patients with alcoholic cirrhosis after liver transplantation

BACKGROUND & AIMS

Occult hepatitis B virus infection (OBI) in patients undergoing liver transplantation (LT) is a suspected source of de novo hepatitis B virus (HBV) infection after LT. This study aimed to investigate the prevalence of OBI in liver transplant recipients with alcoholic cirrhosis and demonstrate the association between OBI and de novo HBV infection after LT in these patients.

METHODS

Forty-three patients with alcoholic cirrhosis who were negative for HBsAg before LT were recruited in this retrospective study. DNA was extracted from paraffin-embedded native liver tissues and quantified for HBV DNA by real-time PCR. Correlation between de novo HBV infection after LT (positive HBsAg and/or detectable HBV DNA in serum) and detection of intrahepatic HBV DNA before LT was analysed.

RESULTS

Detectable HBV DNA in the explanted liver was found in 41.9% (18/43) of the patients and was thus defined as OBI, which was correlated with the presence of serum hepatitis B core antibody (P = 0.008). De novo HBV infection occurred in 18.6% (8/43) of the recipients at a median of 10 months after LT. The rate of de novo HBV infection was 38.9% (7/18) in patients with OBI, compared with 4% (1/25) in patients without OBI (P = 0.004). Furthermore, de novo HBV infection was inversely correlated with the presence of hepatitis B surface antibody in recipients with OBI (P = 0.026).

CONCLUSION

With a prevalence of 41.9% in liver transplant recipients with alcoholic cirrhosis, OBI in the native liver can predict de novo HBV infection after LT.

A novel method for detection of HBVcccDNA in hepatocytes using rolling circle amplification combined with in situ PCR

BACKGROUND

Intrahepatic hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is the original template for HBV replication. The persistence of cccDNA is responsible for the recurrence of HBV infection. The detection of cccDNA can help the development of new antiviral drugs against HBV replication links, and reduce the resistance and recurrence as well as to discover extrahepatic HBV infection. In situ polymerase chain reaction (IS-PCR) can be used to determine the distribution and localization of cccDNA in liver tissues, but it is hampered by its low sensitivity and specificity. We developed a novel method to detect HBV cccDNA using rolling circle amplification (RCA) combined with IS-PCR.

METHODS

Biopsy liver tissues were obtained from 26 patients with HBV infection, including 10 chronic hepatitis B (CHB), 6 liver cirrhosis (LC) and 10 hepatocellular carcinoma (HCC) patients. Four pairs of primers were designed to mediating RCA for the first round amplification of HBV cccDNA specifically. The liver tissue sections from patients were treated by plasmid-safe ATP-dependent DNase (PSAD) prior to RCA. After RCA, HBV cccDNA was further amplified by a pair of selective primers labeled digoxigenin that target the gap region between the two direct repeat regions (DR1 and DR2) of the virus via IS-PCR.

RESULTS

HBVcccDNA was expressed and located in hepatocyte nucleus in 19 patients (73.07%). Compared with the IS-PCR, the introduction of RCA increase the limit of detection. RCA combined with IS-PCR yielded strong positive signals in HCC liver tissue in spite of low copy number cccDNA (2 copies of target sequence per cell), meanwhile, no positive signal was detected via negative control.

CONCLUSIONS

RCA combined with IS-PCR is an effective and practicable method which could detect the presence of low copy number of cccDNA sensitively and specifically, and reflect the relationship between cccDNA expression level and liver tissue pathological characteristics.

Risk factors for de novo hepatitis B infection in pediatric living donor liver transplantation

AIM

To investigate the incidence of de novo hepatitis B virus (HBV) infection after pediatric living donor liver transplantation (LDLT) and to analyze the risk factors associated with this de novo HBV infection.

METHODS

The clinical and laboratory data of children who underwent LDLT from June 2010 to September 2012 in First Center Hospital in Tianjin, China, were retrospectively included in the study. Intrahepatic HBV DNA in donors and recipients was quantified by real-time polymerase chain reaction using DNA extracted from formalin-fixed, paraffin-embedded tissues.

RESULTS

Between June 2010 to September 2012, 32 consecutive pediatric patients underwent LDLT in our institute. Thirty LDLT patients (13 girls and 17 boys) were followed up for a median of 15 mo, of whom 53.3% (16/30) were hepatitis B core antibody (HBcAb) positive and 36.7% (11/30) were hepatitis B surface antibody (HBsAb)/HBcAb positive before transplantation. Sixteen of the children received HBcAb-positive allografts, and 43.7% (7/16) of the grafts were found to be intrahepatic HBV DNA positive. De novo HBV infection developed in 16.1% (5/30) of the children within a median of 11 mo after transplantation. All five of the HBV-infected children had received HBcAb-positive allografts, four of which were intrahepatic HBV DNA positive. Two of the children developed de novo HBV infection despite the preoperative presence of both HBsAb and HBcAb

CONCLUSION

In pediatric recipients, positive intrahepatic HBV DNA in allografts could be a risk factor for de novo HBV infection from HBcAb-positive allografts. HBsAb/HBcAb positivity in pediatric LDLT patients before transplantation exhibited only weak effectiveness in protecting them against de novo HBV infection from HBcAb-positive allografts.

Analysis of hepatitis B virus intrahepatic covalently closed circular DNA and serum viral markers in treatment-naive patients with acute and chronic HBV infection

Background

This study aimed to investigate the relationships of intrahepatic cccDNA with serum HBsAg and with HBV DNA in treatment-naive patients throughout acute and chronic HBV infection.

Methods

A total of 120 patients who had a liver biopsy were enrolled, including 19 with acute hepatitis B (AHB), and 101 patients with chronic HBV infection (CHB) of whom were 10 in immune-tolerant (IT) phase, 59 in immune-clearance (IC) phase, 8 in low-replicative (LR) phase, and 24 in HBeAg-negative hepatitis (ENH) phase. Intrahepatic cccDNA, serum HBsAg and serum HBV DNA levels were comparatively analyzed.

Results

The median intrahepatic cccDNA levels were 0.18 4.80, 3.81, 0.22 and 0.97 copies/cell for patients with AHB, CHB-IT, CHB-IC, CHB-LR, and CHB-ENH, respectively. In AHB patients, intrahepatic cccDNA was positively correlated with serum HBsAg (r = 0.665, P = 0.003), as well as serum HBV DNA (r = 0.536, P = 0.022). In CHB patients, intrahepatic cccDNA was positively correlated with serum HBsAg in the IC phase (r = 0.392, P = 0.005), and with serum HBV DNA in the IC phase (r = 0.301, P = 0.036) and ENH phase (r = 0.588, P = 0.013). HBV replicative efficiency, defined as the ratio of serum HBV DNA to intrahepatic cccDNA, was obviously lower in AHB and CHB-LR patients than in CHB-IT, CHB-IC and CHB-ENH patients (0.70 and 0.53 vs. 1.12, 1.09 and 0.99, P<0.001, values were logarithmic transformed for analysis). In CHB-IC patients, HBV replicative efficiency was positively correlated with histological activity index of liver inflammation (r = 0.308, P = 0.009).

Conclusion

Serum HBsAg and HBV DNA levels may reflect the amount of active intrahepatic cccDNA in treatment-naive AHB and CHB-IC patients. Reduced intrahepatic cccDNA and HBV replicative efficiency may imply effective immune control of HBV infection.

The correlation between T helper type 17 cells and clinical characters in Chinese paediatric patients with chronic hepatitis B

Interleukin (IL)-17-mediated immune response has been shown to play a critical role in inflammation-associated disease. However, its role in the pathogenesis of chronic hepatitis B virus (HBV) in paediatric patients remains unknown. We investigated the frequency of T helper type 17 (Th17) cells and evaluated the association between the Th17 and clinical characters in paediatric patients with chronic hepatitis B (CHB). The frequency of Th17 cells was detected by flow cytometry analyses from 65 paediatric patients with CHB and nine healthy controls. The degree of hepatic inflammation was graded using the histological activity index (HAI). Compared with healthy controls, the frequency of Th17 cells in peripheral blood was significantly higher in paediatric patients with CHB. The proportion of Th17 cells was higher in the patients with higher HAI score (G2-G3) compared to those subjects with lower HAI score (G0-G1), but the frequency of Th17 cells had no correlation with serum HBV DNA loads or alanine aminotransferase levels. Compared with the younger age group (age 1-6 years), Th17 cell frequency was higher in the older age group (age 7-18 years). Peripheral Th17 cell frequency is associated closely with inflammation activity of liver tissues in paediatric patients with CHB.