Establishment and primary application of a mouse model with hepatitis B virus replication

USP18 attenuates the anti-hepatitis B virus effect of IFN by down-regulating JAK-STAT pathway

Aim: USP18 is a type of IFN-stimulated gene, which is associated with virological responses to IFN therapy in HBV (hepatitis B virus). However, its detailed molecular mechanism needs to be explored. Materials & methods: With HBV replication cells and mouse models, the USP18 was overexpressed or inhibited, followed by treatment with IFN or Poly (I:C). The expressions of HBV DNA, HBsAg, HBeAg and protein factors in the samples were detected. Results: Overexpression of USP18 attenuates anti-HBV effect of IFN in vitro and in vivo by inhibiting JAK-STAT pathway and reducing the expression of MX1 and OAS. While, the inhibition of USP18 can promote to activate JAK-STAT pathway to enhance the antiviral effect of IFN. Conclusion: USP18 negatively regulates the anti-HBV effect of IFN by regulating JAK-STAT pathway. It may provide new insights into innate immunity mechanisms in CHB patients receiving IFN treatment.

Interferon-alpha responsible EPN3 regulates hepatitis B virus replication

Hepatitis B virus (HBV) infection remains a major health problem worldwide, and the current antiviral therapy, including nucleoside analogs, cannot achieve life-long cure, and clarification of antiviral host immunity is necessary for eradication. Here, we found that a clathrin-binding membrane protein epsin3 (EPN3) negatively regulates the expression of HBV RNA. EPN3 expression was induced by transfection of an HBV replicon plasmid, and reduced HBV-RNA level in hepatic cell lines and murine livers hydrodynamically injected with the HBV replicon plasmid. Viral RNA reduction by EPN3 was dependent on transcription, and independent from epsilon structure of viral RNA. Viral RNA reduction by overexpression of p53 or IFN-α treatment, was attenuated by knockdown of EPN3, suggesting its role downstream of IFN-α and p53. Taken together, this study demonstrates the anti-HBV role of EPN3. The mechanism how it decreases HBV transcription is discussed.

MCPIP1 reduces HBV-RNA by targeting its epsilon structure

Hepatitis B virus (HBV) is the major causative factor of chronic viral hepatitis, liver cirrhosis, and hepatocellular carcinoma. We previously demonstrated that a proinflammatory cytokine IL-1β reduced the level of HBV RNA. However, the mechanism underlying IL-1β-mediated viral RNA reduction remains incompletely understood. In this study, we report that immune regulator Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) can reduce HBV RNA in hepatocytes. MCPIP1 expression level was higher in the liver tissue of HBV-infected patients and mice. Overexpression of MCPIP1 decreased HBV RNA, whereas ablating MCPIP1 in vitro enhanced HBV production. The domains responsible for RNase activity or oligomerization, were required for MCPIP1-mediated viral RNA reduction. The epsilon structure of HBV RNA was important for its antiviral activity and cleaved by MCPIP1 in the cell-free system. Lastly, knocking out MCPIP1 attenuated the anti-HBV effect of IL-1β, suggesting that MCPIP1 is required for IL-1β-mediated HBV RNA reduction. Overall, these results suggest that MCPIP1 may be involved in the antiviral effect downstream of IL-1β.

Molecular characterization of AID-mediated reduction of hepatitis B virus transcripts

Hepatitis B virus (HBV) is the major cause of liver cirrhosis and hepatocellular carcinoma. After entering a hepatocyte, HBV forms a nuclear viral episome and produces pregenomic (pg) RNA with a stem-loop structure called an epsilon, which acts to signal encapsidation. We previously demonstrated that TGF-β upregulates activation-induced cytidine deaminase (AID) expression in hepatocytes, which in turn downregulates HBV transcripts by recruiting the RNA exosome complex. The molecular mechanism underlying AID-mediated HBV RNA reduction remains largely unclear. Here we used a pgRNA reporter system having a reporter gene within pgRNA to identify sis- and trans-acting elements in AID-mediated HBV RNA reduction. We found that the epsilon RNA and C-terminus of AID are required for AID-mediated HBV RNA reduction. Importantly, this reduction was reproduced in a hydrodynamic HBV transfection mouse model. The molecular mechanism of AID-mediated HBV RNA reduction is discussed.

Fatty acid translocase promoted hepatitis B virus replication by upregulating the levels of hepatic cytosolic calcium

Hepatitis B virus (HBV) is designated a "metabolovirus" due to the intimate connection between the virus and host metabolism. The nutrition state of the host plays a relevant role in the severity of HBV infection. Metabolic syndrome (MS) is prone to increasing HBV DNA loads and accelerating the progression of liver disease in patients with chronic hepatitis B (CHB). Cluster of differentiation 36 (CD36), also named fatty acid translocase, is known to facilitate long-chain fatty acid uptake and contribute to the development of MS. We recently found that CD36 overexpression enhanced HBV replication. In this study, we further explored the mechanism by which CD36 overexpression promotes HBV replication. Our data showed that CD36 overexpression increased HBV replication, and CD36 knockdown inhibited HBV replication. RNA sequencing found some of the differentially expressed genes were involved in calcium ion homeostasis. CD36 overexpression elevated the cytosolic calcium level, and CD36 knockdown decreased the cytosolic calcium level. Calcium chelator BAPTA-AM could override the HBV replication increased by CD36 overexpression, and the calcium activator thapsigargin could improve the HBV replication reduced by CD36 knockdown. We further found that CD36 overexpression activated Src kinase, which plays an important role in the regulation of the store-operated Ca²⁺ channel. An inhibitor of Src kinase (SU6656) significantly reduced the CD36-induced HBV replication. We identified a novel link between CD36 and HBV replication, which is associated with cytosolic calcium and the Src kinase pathway. CD36 may represent a potential therapeutic target for the treatment of CHB patients with MS.

The Prevalence and Replication Capacity of a Tibetan Dominant HBV Strain, C/D Recombinant

This study aimed to estimate the distribution of hepatitis B virus (HBV) C/D recombinant in Han and Tibet patients with chronic hepatitis B (CHB) and then learn such strain's replication capacity in vivo. A total of 331 serum samples were collected from Han outpatients from Sichuan Province and Tibetan outpatients from Tibet. Viral genotypes in these samples were identified. An HBV replicative plasmid of C/D recombinant was constructed with selected genome. Sequentially, HBV replicative mouse models were established and the replication capacity of the viral strain was studied in vivo. In the 314 Han patients, 66% (207) were infected by genotype B strain while 31% (96) were by genotype C strain. Only 1% (3) were by C/D recombinant. In the 17 Tibetan patients, 41% (7) were by genotype D and 35% (6) by C/D recombinant. A plasmid with 1.3 copies of C/D recombinant genome was constructed. And its replication intermediates were found at similar levels to that of genotype D strain. Thus, C/D recombinant, the dominant viral strain in Tibet, was rather rare in the genotype B predominated Han patients from Sichuan Province. And the C/D recombinant replicated at a similar level to viral strain of genotype D in vivo.

Peroxisome Proliferators Activated Receptor (PPAR) agonists activate hepatitis B virus replication in vivo

Background

PPAR agonists are often used in HBV infected patients with metabolic disorders. However, as liver-enriched transcriptional factors, PPARs would activate HBV replication. Risks exsit in such patients. This study aimed to assess the influence of commonly used synthetic PPAR agonists on hepatitis B virus (HBV) transcription, replication and expression through HBV replicative mouse models, providing information for physicians to make necessary monitoring and therapeutic adjustment when HBV infected patients receive PPAR agonists treatment.

Methods

The HBV replicative mouse model was established by hydrodynamic injection of HBV replicative plasmid and the mice were divided into four groups and treated daily for 3 days with saline, PPAR pan-agonist (bezafibrate), PPARα agonist (fenofibrate) and PPARγ agonist (rosiglitazone) respectively. Their serum samples were collected for ECLIA analysis of HBsAg and HBeAg and real-time PCR analysis of Serum HBV DNA. The liver samples were collected for DNA (Southern) filter hybridization of HBV replication intermediates, real-time PCR analysis of HBV mRNA and immunohistochemistry (IHC) analysis of hepatic HBcAg. The alternation of viral transcription, replication and expression were compared in these groups.

Result

Serum HBsAg, HBeAg and HBV DNA were significantly elevated after PPAR agonist treatment. So did the viral replication intermediates in mouse livers. HBV mRNA was also significantly increased by these PPAR agonists, implying that PPAR agonists activate HBV replication at transcription level. Moreover, hepatic HBcAg expression in mouse livers with PPAR agonist treatment was elevated as well.

Conclusion

Our in vivo study proved that synthetic PPAR agonists bezafibrate, fenofibrate and rosiglitazone would increase HBV replication. It suggested that when HBV infected patients were treated with PPARs agonists because of metabolic diseases, HBV viral load should be monitored and regimens may need to be adjusted, an antiviral therapy may be added.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0765-x) contains supplementary material, which is available to authorized users.

Luteolin Inhibits Hepatitis B Virus Replication through Extracellular Signal-Regulated Kinase-Mediated Down-Regulation of Hepatocyte Nuclear Factor 4α Expression

Whether luteolin inhibits HBV replication has not been validated and the underlying mechanism of which has never been elucidated. In this study, we show that luteolin reduces HBV DNA replication in HepG2.2.15 cells. Luteolin effectively inhibited the expression of hepatocyte nuclear factor 4α (HNF4α) and its binding to the HBV promoters in HepG2.2.15 cells. While the extracellular signal-regulated kinase (ERK) was activated by luteolin, inhibition of ERK abolished luteolin-induced HNF4α suppression. Consistently, blocking ERK attenuated the anti-HBV activity of luteolin. In a HBV replication mouse model, luteolin decreased the levels of HBsAg, HBeAg, HBV DNA replication intermediates, and the HBsAg and HBcAg expression. Taken together, our results validated the anti-HBV activity of luteolin in both in vitro and in vivo studies and established a signaling cascade consisting of ERK and HNF4α for inhibition of HBV replication by luteolin, which may be exploited for clinical application of luteolin for anti-HBV therapy.

RPB5-Mediating Protein Suppresses Hepatitis B Virus (HBV) Transcription and Replication by Counteracting the Transcriptional Activation of Hepatitis B virus X Protein in HBV Replication Mouse Model

Background:

RPB5-Mediating protein (RMP) is associated with the RNA polymerase II subunit RPB5. This protein functionally counteracts the transcriptional activation of Hepatitis B Virus X protein (HBx) by competitively binding to the RPB5; however, the effects of RMP on Hepatitis B virus (HBV) transcription and replication remain unknown.

Objectives:

The purpose of this study was to investigate the effect of RMP on viral transcription and replication in vivo by using the hydrodynamic-based HBV replication mouse model.

Materials and Methods:

Male balb/c mice were transfected with wild type (1.2 wt) or the HBx minus HBV plasmids (1.2x (-)) with or without HBx and RMP, to establish an HBV replication mouse model by hydrodynamic injection through the tail vein. The HBV RNA and HBV DNA replication intermediates (RI) were analyzed in the liver.

Results:

RPB5-Mediating protein could inhibit HBV transcription and replication in groups transfected with the 1.2 wt and HBx. The inhibitory effect disappeared in the 1.2x (-) groups, yet it reappeared in the groups co-transfected with 1.2x (-) and HBx. An inhibitory effect was indicated at a low dose of RMP (0.3 ug, 0.5 ug and 0.7 ug) compared to the control group and groups that had received high doses of RMP.

Conclusions:

Our study demonstrated that a low dose of RMP could inhibit HBV transcription and replication, which is dependent on the appearance of HBx in vivo.

Biological characteristics of the A1762T/G1764A mutant strain of hepatitis B virus in vivo

The double nucleotide, A1762T and G1764A exchange (TA mutation), in the hepatitis B virus (HBV) genome basal core promoter (BCP) region is a common viral mutation in patients with chronic HBV infection. This mutation is located in the binding site of hepatocyte nuclear factor 4 (HNF4), and a number of liver‑enriched transcription factors are involved in the regulation of HBV transcription and replication. The aim of the present study was to investigate the biological characteristics of the HBV strain with this mutation, and the effect of HNF4 inhibition on the replication of this strain in vivo. The results indicated that in vivo the HBV strain with the TA mutation supported a higher level of pregenomic RNA transcription and HBV DNA replication, compared with the wild‑type strain. Furthermore, the concentration of serum HBeAg in the TA mutant group was lower than that in the wild‑type strain. Following treatment of the mice with entecavir (ETV) or tenofovir disoproxil fumarate (TDF), the transcription and replication levels of wild‑type and mutant strains were reduced. In the groups treated with TDF, the inhibition effect was more marked. In hepatocytes in which HNF4 expression was specifically inhibited, the level of 3.5 kb mRNA of HBV was reduced compared with that in mouse cells with normal HNF4 expression, and HBV DNA replication levels were also reduced to a greater extent. Furthermore, following liver‑specific knockdown of HNF4, the reduction in variant virus expression was greater than that of the wild‑type virus. In conclusion, the replication capacity of HBV with the TA mutation was increased, and the mutation was associated with a reduction in serum HBeAg levels. This mutant strain remained sensitive to ETV and TDF, and HNF4 supported a higher replication level of TA mutant HBV in vivo.

The infection efficiency and replication ability of circularized HBV DNA optimized the linear HBV DNA in vitro and in vivo

Studies on molecular mechanisms of the persist infection of hepatitis B virus have been hampered by a lack of a robust animal model. We successfully established a simple, versatile, and reproducible HBV persist infection model in vitro and in vivo with the circularized HBV DNA. The cells and mice were transfected or injected with circularized HBV DNA and pAAV/HBV1.2, respectively. At the indicated time, the cells, supernatants, serum samples, and liver tissues were collected for virological and serological detection. Both in vitro and in vivo, the circularized HBV DNA and pAAV/HBV1.2 could replicate and transcribe efficiently, but the infection effect of the former was superior to the latter (p < 0.05). The injection of circularized HBV genome DNA into the mice robustly supported HBV infection and approximately 80% of HBV infected mice established persistent infection for at least 10 weeks. This study demonstrated that the infection efficiency and replication ability of the circularized structure of HBV DNA overmatched that of the expression plasmid containing the linear structure of HBV DNA in vitro and in vivo. Meanwhile, this research results could provide useful tools and methodology for further study of pathogenic mechanisms and potential antiviral treatments of human chronic HBV infection in vitro and in vivo.

The efficacy of zinc finger antiviral protein against hepatitis B virus transcription and replication in tansgenic mouse model

Aim

The zinc finger antiviral protein (ZAP) is a mammalian host restriction factor, and it could inhibit HBV RNA synthesis in vitro experiments. However, the role of ZAP against HBV in vivo environment is unclear. This study aimed to investigate whether ZAP could act against HBV transcription and replication in ZAP tansgenic mouse model.

Methods

HBV-replication-competent plasmid pHBV4.1 was transferred to ZAP transgenic ICR mouse via the tail vein using a hydrodynamic in vivo transfection procedure, and ICR mouse were used as controls. HBV RNA and HBV DNA replication intermediates in the liver were respectively analyzed by Northern blotting and Southern blotting. The expression of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) in the liver tissue was detected by immunohistochemical staining.

Results

As compared to ICR control mouse, the levels of 3.5 kb mRNA in ZAP transgenic mouse were decreased by 8.4%; while the level of HBV DNA replication intermediates was decreased by 82%. In addition, the expression of HBsAg and HBcAg in ZAP transgenic mouse liver were both significantly less than that of ICR control mouse.

Conclusions

Our findings suggest that ZAP could inhibit HBV replication in vivo in mice, which offers a new target for anti-HBV drug development.

Role and functional domain of hepatitis B virus X protein in regulating HBV transcription and replication in vitro and in vivo

The role of hepatitis B virus (HBV) X protein (HBx) in the regulation of HBV replication remains controversial. In the present study, the role of HBx in regulating HBV replication was initially investigated in both HepG2 and Huh7 in vitro cell lines with a transient transfection system. Next, the regions of HBx responsible for transcriptional transactivation and promotion of HBV replication were mapped in an HBV replication mouse model by in vivo transfection of a series of HBx expression plasmids. In an in vitro setting, HBx deficiency had little effect on HBV replication in Huh7 cells, but impaired HBV replication in HepG2 cells. In an in vivo setting, HBx had a strong enhancing effect on HBV transcription and replication. For the C-terminal two-thirds of the protein (amino acids [aa] 51 to 154) was required for this function of HBx, and the regions spanning aa 52 to 72 and 88 to 154 were found to be important for the stimulatory function of HBx on HBV replication. In conclusion, the role of HBx in HBV replication regulation is affected by host cell type, and HBx has an important role in stimulating HBV transcription and replication in hepatocytes in vivo. Further, the transcriptional transactivation function of HBx may be crucial for its stimulatory effect on HBV transcription and replication.

Biological characteristics of the rtA181T/sW172* mutant strain of Hepatitis B virus in animal model

Background

The effects of Hepatitis B virus (HBV) rtA181T/sW172* mutation on viral replication and pathogenicity was concerned recently. This study aimed to investigate the biological characteristics of rtA181T/sW172* mutant strain of HBV in animal model.

Methods

The rtA181T/sW172* mutant plasmid was constructed using the pHBV4.1 (wild type HBV) as a template. The wild and mutant HBV replication mouse models were established utilizing a hydrodynamic technique. The titers of hepatitis B surface antigen (HBsAg), hepatitis B e antigen, and HBV DNA in serum, and the levels of HBsAg, hepatitis B core antigen(HBcAg), HBV DNA replication intermediates (HBV DNA RI) and HBV RNA in liver were measured after 1, 3, 5, 7, 10, 12 and 15 days of plasmid injection.

Results

In wild-type HBV replication mouse model, serum HBsAg was high on day 1, 3, and 5, but became lower since day 7; while in mutant HBV mouse model, serum HBsAg was always at very low level. In liver tissues, HBV DNA RI of wild type HBV was detected on day 1 after transfection. The level subsequently peaked on day 3, gradually declined after day 5, and was almost undetectable on day 10. However, the HBV DNA RI levels of the mutant strain were always higher and lasted longer until day 15. Consistently, the expression levels of HBsAg and HBcAg in liver of the mutant group were significantly increased.

Conclusions

In the case of the HBV rtA181T/sW172* mutation, the secretion of serum HBsAg was impaired, whereas HBV DNA replication and HBsAg/HBcAg expression were increased in liver. These results suggest that the mutation can impair HBsAg secretion, and may cause the accumulation of viral core particles in liver.

Inhibition of hepatitis B virus and induction of hepatoma cell apoptosis by ASGPR-directed delivery of shRNAs

Hepatitis B virus (HBV) infection is a worldwide liver disease and nearly 25% of chronic HBV infections terminate in hepatocellular carcinoma (HCC). Currently, there is no effective therapy to inhibit HBV replication and to eliminate hepatoma cells, making it highly desired to develop novel therapies for these two stages of the HBV-caused detrimental disease. Recently, short hairpin RNA (shRNA) has emerged as a potential therapy for virus-infected disease and cancer. Here, we have generated a shRNA, pGenesil-siHBV4, which effectively inhibits HBV replication in the human hepatoma cell line HepG2.2.15. The inhibitory effects of pGenesil-siHBV4 are manifested by the decrease of both the HBV mRNA level and the protein levels of the secreted HBV surface antigen (HBsAg) and HBV e antigen (HBeAg), and by the reduction of secreted HBV DNA. Using mouse hydrodynamic tail vein injection, we demonstrate that pGenesil-siHBV4 is effective in inhibiting HBV replication in vivo. Because survivin plays a key role in cancer cell escape from apoptosis, we further generated pGenesil-siSurvivin, a survivin-silencing shRNA, and showed its effect of triggering apoptosis of HBV-containing hepatoma cells. To develop targeted shRNA therapy, we have identified that as a specific binder of the asialoglycoprotein receptor (ASGPR), jetPEI-Hepatocyte delivers pGenesil-siHBV4 and pGenesil-siSurvivin specifically to hepatocytes, not other types of cells. Finally, co-transfection of pGenesil-siHBV4 and pGenesil-siSurvivin exerts synergistic effects in inducing hepatoma cell apoptosis, a novel approach to eliminate hepatoma by downregulating survivin via multiple mechanisms. The application of these novel shRNAs with the jetPEI-Hepatocyte targeting strategy demonstrates the proof-of-principle for a promising approach to inhibit HBV replication and eliminate hepatoma cells with high specificity.

Functional Characterization of Interferon Regulation Element of Hepatitis B virus Genome In Vivo

The roles of interferon regulatory element (IRE) in Hepatitis B virus (HBV) genome on inhibitory effect of interferon against HBV are controversial in vitro. This study aimed to determine the functional characterization of HBV-IRE sequence in vivo. Wild-type or IRE-mutant HBV replication-competent mice were firstly established, and mice were subquently treated with polyinosinic-polytidylin acid (polyI.C) or phosphate-buffered saline via intraperitoneal. Results showed that PolyI.C inhibited viral replication, and increased the level of 2',5'-oligoadenylate synthase mRNA transcripts, a marker of INF-α/β induction. Between wild-type and IRE-mutant HBV replication-competent mice, the levels of HBV-RNA and HBV-DNA replication intermediates were similar. After PolyI.C treatment, the decreasing of HBV-RNA was similar between two groups, but HBV-DNA replication intermediates decreased significantly less in IRE-mutant than wild-type HBV replication-competent mice. These findings suggested that IRE mutant reduced the inhibitory effect of interferon on HBV replication, which played a role in antiviral effect of interferon against HBV.

Inhibition of hepatitis B Virus replication by hepatocyte nuclear factor 4-alpha specific short hairpin RNA

BACKGROUND

Previous studies showed that hepatocyte nuclear factor 4α (HNF4α) may play a critical role in hepatitis B virus (HBV) replication.

AIMS

This study aimed to investigate the effect of knocking down of HNF4α with RNA interference technique on HBV replication in a HBV replication mouse model.

METHODS

Four HNF4α, specific short hairpin RNA (shRNA)-producing plasmids were constructed. HBV mRNA and DNA replication intermediates were analysed using Northern and Southern blot respectively. The expression of HNF4α and HBV core antigen (HBcAg) was detected using immunohistochemistry technique.

RESULTS

One of the HNF4α shRNAs, HNF4α shRNA1, efficiently inhibited the expression of HNF4α in HepG2 cells and mice liver. HBV RNA transcripts and DNA replication intermediates in HNF4α shRNA1 group were decreased 67.3 and 76%, respectively, in HepG2 cells, and 68.1 and 70.6% in mice liver respectively. The expression level of HBcAg in the liver was also decreased with the inhibition of HNF4α expression.

CONCLUSIONS

These results suggested that decreasing of HNF4α expression was associated with the reduced level of HBV replication in HepG2 cells and mice liver. These data indicated that HNF4α played a critical role in HBV replication in vivo, and HNF4α shRNA could inhibit HBV replication in vivo.

Application of hepatitis B virus replication mouse model

AIM: To evaluate the value of the hepatitis B virus (HBV) replication mouse model with regard to several aspects of the study of HBV biology.

METHODS: To evaluate the HBV replication mouse model in detecting the efficacy of anti-HBV agents, the interferon inducer polyinosinic-polytidylin acid (polyIC) and nucleotide analogues adefovir and entecavir were administered to mice injected with wild type pHBV4.1, and the inhibiting effect of these agents on HBV DNA replication was evaluated. To identify the model’s value in a replication ability study of HBV drug-resistant mutants and a HBx-minus mutant, telbivudine resistance mutants (rtM204I, ayw subtype), adefovir resistance mutants (rtA181V + rtN236T, ayw subtype) and HBx-minus mutants were injected respectively, and their corresponding HBV DNA replication intermediates in mouse liver were assessed.

RESULTS: Compared with the wild type HBV replication mouse model without antiviral agent treatment, the HBV DNA replication intermediates of the polyIC-treated group were decreased 1-fold; while in the entecavir- and adefovir-treated groups, the levels of HBV DNA replication intermediates were inhibited 13.6-fold and 1.4-fold, respectively. For the mouse models injected with telbivudine resistance mutant, adefovir resistance mutant and HBx-minus mutant, HBV DNA replication intermediates could still be detected, but the levels of HBV DNA replication intermediates of these mutants decreased 4.5-fold, 5.6-fold and 2.9-fold respectively, compared with the mouse model with wild type HBV plasmid.

CONCLUSION: The HBV replication mouse model we established was a useful and convenient tool to detect the efficacy of antiviral agents and to study the replication ability of HBV mutants in vivo.