Application of hepatitis B virus replication mouse model

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.

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.

Correlation between the suppressor of cytokine signaling-1 and 3 and hepatitis B virus: possible roles in the resistance to interferon treatment

BACKGROUND

The suppressor of cytokine signaling family (SOCS) is an important negative regulator in the JAK-STAT signaling pathway. This study was designed to explore the correlation between SOCS-1, 2 and 3, Hepatitis B Virus (HBV) and interferon (IFN), and the relationship between SOCS and IFN therapeutic efficacy.

METHODS

Four types of mouse models were established. Mice were administered with HBV replicative plasmid pHBV4.1 and IFN inducer Poly IC (Group A), pHBV4.1 (Group B), Poly IC (Group C) and saline (Group D), respectively. Liver tissues were harvested from the mice and SOCS expression was determined. Meanwhile, patients with chronic hepatitis B (CHB) were treated with pegylated interferon α-2b for 24-48 weeks. Liver biopsy was collected and the baseline SOCS expression was determined. Serum assay was performed for efficacy evaluation and correlation analysis.

RESULTS

In animal studies, the expression level of SOCS-1 and 3 was found in the descending order of B, A, C and D. The difference between Group B and D suggested that HBV could induce SOCS. The difference between Group A and C suggested that HBV could still induce SOCS with up-regulated endogenous IFN. The difference between Group C and D suggested that ploy IC could induce SOCS, while the difference between Group B and A suggested that Poly IC might have a stronger inhibition effect for SOCS. There was no difference in SOCS-2 expression. In clinical studies, eight of twenty-four enrolled patients achieved either complete or partial therapeutic response. The expression of both SOCS-1 and 3 was higher in CHB patients than in normal controls. The baseline HBV-DNA level was positively correlated with SOCS-1 and 3. The age, viral genotype, HBVDNA, SOCS-1 and SOCS-3 were found to be related to IFN efficacy.

CONCLUSION

HBV could induce both SOCS-1 and 3 expression regardless of endogenous IFN level. Elevated IFN could directly up-regulate SOCS-1 and 3 expression, but it could also indirectly down-regulate SOCS-1 and 3 expression by inhibiting HBV replication. HBV might play a more important role in the SOCS up-regulation than IFN, a possible reason why patients with high HBV viral load encounter poor efficacy of IFN treatment.

Establishment and application of hepatitis B virus persistent replication model in IFNAR(-/-) mouse

The type I interferon and IFNAR play an important role in hepatitis B virus (HBV) infection and anti-HBV therapy. However, its mechanism of action is still poorly understood. To gain more insights into the role of type I interferon and type I interferon receptor (IFNAR) in HBV infection, we established an HBV persistent replication IFNAR knockout (IFNAR(-/-)) mouse model and preliminarily applied this model. At first, the progeny of IFNAR(-/-) mouse was reproduced. Then hydrodynamic injection with pAAV/HBV1.2 plasmid was conducted to establish the persistent HBV replication IFNAR(-/-) mouse model. At last, we applied this model to evaluate the effect of nucleoside analogues entecavir (ETV) on HBV replication. It was found that there was no difference in the serum HBsAg and HBeAg levels and HBcAg expression in the liver tissue between the ETV treated groups and normal saline (NS) treated group, but the serum HBV DNA levels were significantly suppressed 10, 25, 40 and 55 days after the ETV treatment [P=0.035, P=0.00, P=0.149 and P=0.084, IFNAR knockout (KO) control group vs. C57BL/6 ETV groups, respectively; P=0.081, P=0.001, P=0.243 and P=0.147, IFNAR KO control group vs. IFNAR KO ETV groups, respectively]. Interestingly, there was no difference in serum HBV DNA levels between the ETV treated IFNAR(-/-) and C57BL/6 mice. This result suggests that HBV suppression during ETV treatments doesn't depend on type I interferon and IFNAR. Collectively, persistent HBV replication IFNAR(-/-) mouse model that we established is a useful and convenient tool to detect the function of the type I interferon and IFNAR in HBV infection and anti-HBV treatments.

Successful establishment and evaluation of a new animal model for studying the hepatitis B virus YVDD mutant

The treatment of infection with lamivudine-resistant mutants of hepatitis B virus (HBV) with mutations in the YMDD motif has become a crucial issue in the clinic. In this work, the plasmids pcDNA3.1 (+)-HBV/C-YVDD and pcDNA3.1 (+)-HBV/C-YMDD were constructed and injected into BALB/c mice using a hydrodynamics-based procedure to investigate viral replication and expression of HBV lamivudine-resistant YVDD mutants in vivo. Compared with the YMDD group, HBsAg levels were higher in sera of mice in the YVDD group, but HBeAg levels were lower on day 1 after injection. Levels of HBcAg in hepatocytes were higher in the YVDD group on day 1, whereas the HBsAg levels were lower. The levels of HBV mRNA in the liver were higher in mice in the YVDD group on day 1 after injection. The results showed that injection with these plasmids resulted in efficient initiation of replication of HBV in mice and also suggested that the combined mutations in YVDD mutants could affect the replication process.

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.