Recent developments in antivirals against hepatitis B virus

Exploring the potential of structural modeling and molecular docking for efficient siRNA screening: A promising approach to Combat viral mutants, with a focus on HIV-1

RNA interference (RNAi) holds immense potential for sequence-specific downregulation of disease-related genes. Small interfering RNA (siRNA) therapy has made remarkable strides, with FDA approval for treating specific human diseases, showcasing its promising future in disease treatment. Designing highly efficient siRNAs is a critical step in this process. Previous studies have introduced various algorithms and parameters for siRNA design and scoring. However, these attempts have often fallen short of meeting all essential criteria or required modifications, resulting in variable and unclear effectiveness of screened siRNAs, particularly against viral mutants with non-conserved short sequences. In this study, we present a fully optimized siRNA screening system considering all necessary parameters. Notably, we highlight the critical role of molecular docking simulations between siRNA and two functional domains of the Argonaute protein (PAZ and PIWI) in identifying the most efficient siRNAs, since the appropriate interaction between the guide siRNA strand and the RISC complex is crucial. Through our stringent method, we designed approximately 50 potential siRNAs targeting the HIV-1 vpr gene. Evaluation through XTT, qRT-PCR, and flow cytometry analysis on RAW 264.7 macrophage stable cells revealed negligible cytotoxicity and exceptional gene-silencing efficiency at both the transcriptional and translational levels for the top-ranked screened siRNAs. Given the growing interest in siRNA-based therapeutics, we anticipate that the insights from this study will contribute to improving treatment strategies against mutant viruses, particularly HIV-1.

A novel phthalazinone derivative as a capsid assembly modulator inhibits hepatitis B virus expression

Development of new anti-hepatitis B virus (HBV) drugs that target viral capsid assembly is a very active research field. We identify a novel phthalazinone derivative, compound 5832, as a potent HBV inhibitor. In this study, we intend to elaborate the antiviral effect and mechanism of 5832 against HBV in vitro and in vivo. Compound 5832 treatment induces the formation of genome-free empty capsid by interfering with the core protein assembly domain, which significantly decreases the extracellular and intracellular HBV DNA. In the AAV-HBV transduced mouse model, 5832 suppresses serum HBV DNA after 4-week treatment, and decreases HBsAg and HBeAg levels. 5832 treatment also reduces intrahepatic HBV RNA, DNA and HBcAg levels. During the follow-up period after treatment withdrawal, serum antigen levels demonstrated no increase. We demonstrate 5832 treatment could active apoptotic signaling by elevating the expression of death receptor 5 (DR5), which participated in corresponding HBcAg-positive hepatocyte eradication. Phthalazinone derivative 5832 may serve as a promising anti-HBV drug candidate to improve the treatment options for chronic HBV infection.

Delivery of siRNAs against MERS-CoV in Vero and HEK-293 cells: A comparative evaluation of transfection reagents

Background

A new coronavirus was identified in Jeddah, Saudi Arabia in 2012 and designated as Middle East Respiratory Syndrome Coronavirus (MERS-CoV). To date, this virus has been reported in 27 countries. The virus transmission to humans has already been reported from camels. Currently, there is no vaccine or antiviral therapy available against this virus.

Methods

The siRNAs were in silico predicted, designed, and chemically synthesized by using the MERS-CoV-orf1ab region as a target. The antiviral activity was experimentally evaluated by delivering the siRNAs with Lipofectamine™ 2000 and JetPRIME^R as transfection reagents in both Vero cell and HEK-293-T cell lines at two different concentrations (10.0 nM and 5.0 nM). The Ct value of quantitative Real-Time PCR (qRT-PCR) was used to calculate and determine the reduction of viral RNA level in both cell supernatant and cell lysate isolated from both cell lines.

Results

The sequence alignment resulted in the selection of highly conserved regions. The orf1ab region was used to predict and design the siRNAs and a total of twenty-one siRNAs were finally selected from four hundred and twenty-six siRNAs generated by online software. Inhibition of viral replication and significant reduction of viral RNA was observed against selected siRNAs in both cell lines at both concentrations. Based on the Ct value, the siRNAs # 11, 12, 18, and 20 were observed to be the best performing in both cell lines at both concentrations.

Conclusion

Based on the results and data analysis, it is concluded that the use of two different transfection reagents was significantly effective. But the Lipofectamine™ 2000 was found to be a better transfection reagent than the JetPRIME^R for the delivery of siRNAs in both cell lines.

Computational Design and Experimental Evaluation of MERS-CoV siRNAs in Selected Cell Lines

Middle East respiratory syndrome coronavirus (MERS-CoV) is caused by a well-known coronavirus first identified in a hospitalized patient in the Kingdom of Saudi Arabia. MERS-CoV is a serious pathogen affecting both human and camel health globally, with camels being known carriers of viruses that spread to humans. In this work, MERS-CoV genomic sequences were retrieved and analyzed by multiple sequence alignment to design and predict siRNAs with online software. The siRNAs were designed from the orf1ab region of the virus genome because of its high sequence conservation and vital role in virus replication. The designed siRNAs were used for experimental evaluation in selected cell lines: Vero cells, HEK-293-T, and Huh-7. Virus inhibition was assessed according to the cycle threshold value during a quantitative real-time polymerase chain reaction. Out of 462 potential siRNAs, we filtered out 21 based on specific selection criteria without off-target effect. The selected siRNAs did not show any cellular toxicity in the tested cell lines at various concentrations. Based on our results, it was obvious that the combined use of siRNAs exhibited a reduction in MERS-CoV replication in the Vero, HEK-293-T, and Huh-7 cell lines, with the highest efficacy displayed in the Vero cells.

Inhibition of hepatic NLRP3 inflammasome ameliorates non-alcoholic steatohepatitis/hepatitis B - induced hepatic injury

BACKGROUND AND AIM

Both chronic hepatitis B (CHB) and non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) are the most common liver diseases over the world, but their underlying pathological mechanisms and interrelations are poorly understood.

METHODS

Histological analysis and NLRP3 protein expression were performed on 130 CHB patients with liver-biopsied. Wild-type or NLRP3 knockdown hepatitis B virus (HBV) -transgenic mice were fed with high-fat diet to induce steatosis, with or without co-administration with a novel NLRP3 inhibitor MCC950.

RESULTS

Hepatic NLRP3 inflammasome is markedly up-regulated in the CHB, NASH, superimposed NASH with CHB patients and their corresponding model mice. Hepatic knock-down of NLRP3 significantly inhibits HBV replication and surface antigen expression, as well as ameliorates NASH typical symptoms of HBV transgenic mice with or without high-fat diet consumption. In addition, administration of MCC950 successfully inhibits pathological features of both CHB and steatosis-induced liver damage without detectable adverse effects.

CONCLUSIONS

NLRP3 inflammasome is activated during the progression of both CHB and NASH and may play a critical role in their pathogenesis by regulating hepatic inflammation. Targeting this protein platform may represent an effective and novel strategy for the treatment of CHB, NASH and the superimposed patients.

Analysis of the Differential Expression and Antiviral Activity of Porcine Interferon-α In Vitro

Porcine interferon α (poIFN-α) is a crucial cytokine that can prevent and treat viral infections. Seventeen functional porcine IFN-α subtypes were found in the porcine genome. In this study, multiple sequence alignment was performed to analyze IFN-α protein structure and function. Phylogenetic tree analysis of the poIFN gene family defined the evolutionary relationship of various subtypes. PoIFN-αs, including poIFN-α1-17, were expressed in an Escherichia coli expression system. The antiviral activities of these IFN-α proteins against vesicular stomatitis virus (VSV) and pseudorabies virus (PRV) were examined in PK-15 cells. We found that the antiviral activity of different poIFN-α molecules greatly differed as follows: the poIFN-α14 and 17 subtypes had the greatest antiviral activities against VSV and PRV in PK-15 cells, poIFN-α1, 2, 3, and 8 exhibited lower biological activities, and poIFN-α4, 5, 6, 7, 9, 10, 11, 12, 13, and 16 had minimal or no effect in the tested target cell‒virus systems. Moreover, our studies demonstrated that the antiviral activity of IFN-α was positively correlated with the induction of IFN-stimulated genes, such as 2'-5' oligoadenylate synthetase 1 (OSA1), interferon-stimulated gene 15 (ISG15), myxoma resistance protein 1 (Mx1), and protein kinase R (PKR). Thus, our experimental results provide important information about the antiviral functions and mechanism of poIFN-α.

A Comprehensive Account on Recent Progress in Pharmacological Activities of Benzimidazole Derivatives

Nowadays, nitrogenous heterocyclic molecules have attracted a great deal of interest among medicinal chemists. Among these potential heterocyclic drugs, benzimidazole scaffolds are considerably prevalent. Due to their isostructural pharmacophore of naturally occurring active biomolecules, benzimidazole derivatives have significant importance as chemotherapeutic agents in diverse clinical conditions. Researchers have synthesized plenty of benzimidazole derivatives in the last decades, amidst a large share of these compounds exerted excellent bioactivity against many ailments with outstanding bioavailability, safety, and stability profiles. In this comprehensive review, we have summarized the bioactivity of the benzimidazole derivatives reported in recent literature (2012-2021) with their available structure-activity relationship. Compounds bearing benzimidazole nucleus possess broad-spectrum pharmacological properties ranging from common antibacterial effects to the world's most virulent diseases. Several promising therapeutic candidates are undergoing human trials, and some of these are going to be approved for clinical use. However, notable challenges, such as drug resistance, costly and tedious synthetic methods, little structural information of receptors, lack of advanced software, and so on, are still viable to be overcome for further research.

In Vitro Inhibitory Analysis of Rationally Designed siRNAs against MERS-CoV Replication in Huh7 Cells

MERS-CoV was identified for the first time in Jeddah, Saudi Arabia in 2012 in a hospitalized patient. This virus subsequently spread to 27 countries with a total of 939 deaths and 2586 confirmed cases and now has become a serious concern globally. Camels are well known for the transmission of the virus to the human population. In this report, we have discussed the prediction, designing, and evaluation of potential siRNA targeting the ORF1ab gene for the inhibition of MERS-CoV replication. The online software, siDirect 2.0 was used to predict and design the siRNAs, their secondary structure and their target accessibility. ORF1ab gene folding was performed by RNAxs and RNAfold software. A total of twenty-one siRNAs were selected from 462 siRNAs according to their scoring and specificity. siRNAs were evaluated in vitro for their cytotoxicity and antiviral efficacy in Huh7 cell line. No significant cytotoxicity was observed for all siRNAs in Huh7 cells. The in vitro study showed the inhibition of viral replication by three siRNAs. The data generated in this study provide preliminary and encouraging information to evaluate the siRNAs separately as well as in combination against MERS-CoV replication in other cell lines. The prediction of siRNAs using online software resulted in the filtration and selection of potential siRNAs with high accuracy and strength. This computational approach resulted in three effective siRNAs that can be taken further to in vivo animal studies and can be used to develop safe and effective antiviral therapies for other prevalent disease-causing viruses.

In silico prediction and experimental validation of siRNAs targeting ORF1ab of MERS-CoV in Vero cell line

The Middle East Respiratory Syndrome Coronavirus is well known to cause respiratory syndrome and this virus was identified and isolated for the first time from Jeddah, Saudi Arabia in 2012 from infected patient. In this report, we have conducted the in-silico prediction, designing and evaluation of siRNAs targeting Middle East Respiratory Syndrome Coronavirus orf1ab gene to inhibit the virus replication. By using bioinformatics software, total twenty-one functional, off-target reduced siRNA were selected from four hundred and sixty-two siRNAs based on their greater potency and specificity. We have evaluated only seven siRNAs to analyze their performance and efficacy as antivirals by reverse transfection approach in Vero cells. There was no cytotoxicity of siRNAs at various concentrations was observed in Vero cells. Based on the real-time PCR results, better inhibition of viral replication was observed in the siRNA-1 and 4 as compared to other siRNAs. The results generated from this work provided suitable information about the efficacy of siRNAs which encouraged us to further evaluate the remaining siRNAs to determine their inhibitory effect on the virus replication. We concluded that the insilico prediction and designing resulted in the screening of potential siRNAs with better efficiency, and strength. This can be used to develop oligonucleotide-based antiviral therapeutics against MERS-CoV in the near future.

Cross-sectional retrospective analysis of clinical characteristics of chronic hepatitis B patients with oral antiviral treatment in eastern China

BACKGROUND

In China, more than 20 million patients with chronic hepatitis B need antiviral treatment. Side effects of antiviral treatment such as renal complications can be problematic, particularly in an aging population.

METHODS

The data were retrospectively extracted from the hospital medical charts of five centers in eastern China from January 1 to December 31, 2018.

RESULTS

A total of 8309 patients with CHB was enrolled in this study. The median age of the patients was 46 years. The prevalence of diabetes mellitus, hypertension, and hepatic cirrhosis was respectively 3.49%, 4.42%, and 23.72%. The prevalence of these comorbidities increased with age (P < 0.001). Of the patients with CHB, 5332 had complete renal function results. Among them, patients with an estimated glomerular filtration rate of < 60 mL/min/1.73m² accounted for 4.14%, and those with proteinuria for 8.33%. According to the definition of chronic kidney disease, the proportion of patients with chronic kidney disease was 11.37%. The prevalence of chronic kidney disease increased with age (P < 0.001). In a multivariate analysis, age group [odds ratio (OR) = 2.387], diabetes mellitus (OR = 1.486), hypertension (OR = 2.557), hepatic cirrhosis (OR = 1.295), and a history of exposure to adefovir dipivoxil (OR = 1.644) were significantly associated with CKD (P < 0.05). Among patients with CKD, 17.66% (107/606) had a history of lamivudine exposure, and 34.65% (210/606) had a history of nucleotide analogue exposure CONCLUSION: The management of Chinese patients with CHB should take into consideration age, previous medication history, and renal impairment.

Designing and evaluation of MERS-CoV siRNAs in HEK-293 cell line

Background

The MERS-CoV was identified for the first time from Jeddah, Saudi Arabia in 2012 from a hospitalized patient. This virus has now been spread to 27 countries with a total of 858 deaths and 2494 confirmed cases and has become a serious concern for the human population. Camels are well known for the transmission of the virus to the human population.

Methods

In this report, we have discussed the designing, prediction, and evaluation of potential siRNAs against the orf1ab gene of MERS-CoV. The online software was used to predict and design the siRNAs and finally, total twenty-one siRNA were filtered out from four hundred and sixty-two sIRNAs as per their scoring and specificity criteria. We have used only ten siRNAs to evaluate their cytotoxicity and efficacy by reverse transfection approach in HEK-293-T cell lines.

Results

Based on the results and data generated; no cytotoxicity was observed for any siRNAs at various concentrations in HEK-293-T cells. The ct value of real-time PCR showed the inhibition of viral replication in siRNA-1, 2, 4, 6, and 9. The data generated provided the preliminary information and encouraged us to evaluate the remaining siRNAs separately as well as in combination to analyses the replication of MERS-CoV inhibition in other cell lines.

Conclusion

Based on the results obtained; it is concluded that the prediction of siRNAs using online software resulted in the filtration of potential siRNAs with high accuracy and strength. This technology can be used to design and develop antiviral therapy not only for MERS-CoV but also against other viruses.

PD-L1 is induced on the hepatocyte surface via CKLF-like MARVEL transmembrane domain-containing protein 6 up-regulation by the anti-HBV drug Entecavir

Chronic hepatitis B is now controllable when treated with nucleoside reverse transcriptase inhibitors (NRTIs), which inhibit hepatitis B virus (HBV) replication. However, once the NRTIs are discontinued, most patients relapse, necessitating lifelong NRTIs treatment. HBV infection relapse is assumed to be caused by the persistent existence of covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes. The mechanism by which cccDNA-positive hepatocytes escape immune surveillance during NRTIs treatment remains elusive. Entecavir (ETV), a commonly used NRTI, post-transcriptionally up-regulates programmed cell death-ligand 1 (PD-L1), an immune checkpoint molecule, on the cell surface of hepatocytes regardless of HBV infection. Up-regulation by ETV depends on up-regulation of CKLF-like MARVEL transmembrane domain-containing 6, a newly identified potent regulator of PD-L1 expression on the cell surface. ETV-treated hepatic cells suppressed the activity of primary CD3 T cells and programmed cell death protein-1 (PD-1)-over-expressed Jurkat cells. Finally, ETV induces PD-L1 in primary hepatocytes infected by HBV. These results provide evidence that ETV considerably up-regulates PD-L1 on the cell surface of infected hepatocytes, which may be one of the mechanisms by which infected hepatocytes subvert immune surveillance.

Generating DNA Expression Cassettes Encoding Multimeric Artificial MicroRNA Precursors

RNA interference (RNAi) is a promising tool for the treatment of chronic viral infection, such as that caused by the hepatitis B virus (HBV). RNAi activators, including expressed primary microRNA (pri-miRNA) mimics, can effectively silence viral gene expression and thereby inhibit viral replication. Here we describe a protocol for the design, generation and functional assessment of cassettes encoding effective single and multimeric pri-miRNA mimics. Artificial miRNAs targeting viral genes can be identified in silico and used to design corresponding pri-miRNA mimics. A two-step generation and TA cloning protocol can be used to produce single mimics, while the strategic use of restriction sites enables concatenation of mimics in a sub-cloning protocol. Basic gene silencing function of pri-miRNA mimics in cell culture can then be assessed using a dual luciferase assay and appropriate minimal targets. The methods described here for the generation of effective pri-miRNA mimics targeting HBV can be applied in the silencing of other viral or endogenous genes.

Humanized Mice as an Effective Evaluation System for Peptide Vaccines and Immune Checkpoint Inhibitors

Peptide vaccination was developed for the prevention and therapy of acute and chronic infectious diseases and cancer. However, vaccine development is challenging, because the patient immune system requires the appropriate human leukocyte antigen (HLA) recognition with the peptide. Moreover, antigens sometimes induce a low response, even if the peptide is presented by antigen-presenting cells and T cells recognize it. This is because the patient immunity is dampened or restricted by environmental factors. Even if the immune system responds appropriately, newly-developed immune checkpoint inhibitors (ICIs), which are used to increase the immune response against cancer, make the immune environment more complex. The ICIs may activate T cells, although the ratio of responsive patients is not high. However, the vaccine may induce some immune adverse effects in the presence of ICIs. Therefore, a system is needed to predict such risks. Humanized mouse systems possessing human immune cells have been developed to examine human immunity in vivo. One of the systems which uses transplanted human peripheral blood mononuclear cells (PBMCs) may become a new diagnosis strategy. Various humanized mouse systems are being developed and will become good tools for the prediction of antibody response and immune adverse effects.

Proposed model for the prediction of intrahepatic covalently closed circular DNA level in patients with chronic hepatitis B

AIM

We sought to create a prediction model for intrahepatic covalently closed circular DNA (IH-cccDNA) level in chronic hepatitis B (CHB) patients and to validate the model's predictive accuracy.

METHODS

Patients who did not receive previous nucleoside analogue (NA) therapy were assigned to the training cohort (n = 57), and those who received previous NA therapy were assigned to the validation cohort (n = 69). Factors linked to IH-cccDNA levels in the training cohort were analyzed and a formula to predict IH-cccDNA levels was constructed. Next, the reproducibility of that formula was assessed.

RESULTS

In the multivariate analysis for the prediction of IH-cccDNA level in the training cohort, fasting blood sugar (FBS) (P = 0.0227), hepatitis B e antigen (HBeAg) (P = 0.0067) and log₁₀ (HB surface antigen [HBsAg]) (P = 0.0497) were significant, whereas HB core-related antigen (HBcrAg) tended to be significant (P = 0.0562). The formula was constructed and named the FBS-cres score based on the variables used (FBS, HBcrAg, HBeAg, and HBsAg). The FBS-cres score was calculated as: 3.1686 - (0.0148 × FBS) + (0.1982 × HBcrAg) + (0.0008168 × HBeAg) + (0.1761 × log₁₀ (HBsAg)). In the training cohort, a significant correlation was noted between HBcrAg and IH-cccDNA levels (P < 0.0001, r = 0.67), whereas the FBS-cres score was more closely correlated to IH-cccDNA level (P < 0.0001, r = 0.81). In the validation cohort, significant correlation was found between HBcrAg and IH-cccDNA levels (P = 0.0012, r = 0.38), whereas the FBS-cres score was more closely linked to IH-cccDNA levels (P < 0.0001, r = 0.51). Similar tendencies were observed in all subgroup analyses.

CONCLUSION

Our proposed model for the prediction of IH-cccDNA level could be helpful in CHB patients.

The immunological function of extracellular vesicles in hepatitis B virus-infected hepatocytes

Hepatitis B virus (HBV) generates large amounts of complete and incomplete viral particles. Except for the virion, which acts as infectious particles, the function of those particles remains elusive. Extracellular vesicles (EVs) have been revealed to have biological functions. The EVs which size are less than 100 nm in diameter, were collected from HBV infected-patients. These vesicles contain, complete and incomplete virions, and exosomes, which have been recently shown to be critical as intercellular communicators. Here, the effects of the exosome, the complete, and the incomplete particles on the target cells were investigated. These particles are endocytosed by monocyte/macrophages and function primarily to upregulate PD-L1. The functions and composition of the EVs were affected by nucleotide reverse transcriptase inhibitors (NRTIs), suggesting that the EVs are involved in the pathogenesis of HBV hepatitis and clinical course of those patients treated by NRTIs.

Ideal Cure for Hepatitis B Infection: The Target is in Sight

Hepatitis B virus (HBV) is one of the most common causes of liver cirrhosis and hepatocellular carcinoma. Despite recent strides in pharmacotherapy, complete cure of HBV infection still remains an enigma. The biggest obstacle in HBV therapy is clearance of covalently closed circular deoxyribonucleic acid (cccDNA). We discuss about the role of cccDNA in HBV life cycle, efficacy and shortcomings of currently available antivirals as well as promising novel targets to achieve ideal HBV cure.

Dynamic Characteristics of Serum Hepatitis B Surface Antigen in Chinese Chronic Hepatitis B Patients Receiving 7 Years of Entecavir Therapy

Background:

The ultimate goal of hepatitis B treatment is hepatitis B surface antigen (HBsAg) seroclearance. Several factors have been suggested to be associated with the rate of HBsAg reduction in antiviral-naive or lamivudine therapy cohorts. However, there are few studies evaluating the factors during long-term entecavir (ETV) therapy. In the present study, we aimed to evaluate the factors to predict the outcome of ETV therapy for 7 years.

Methods:

A total of 47 chronic hepatitis B (CHB) patients treated with ETV monotherapy were included in this study. Liver biochemistry, hepatitis B virus (HBV) serological markers, serum HBV DNA, and HBsAg titers were tested at baseline, 3 months, 6 months, and yearly from 1 to 7. The associations between factors and HBsAg reduction were assessed using multivariate tests with repeated measure analysis of variance.

Results:

At baseline, serum HBsAg levels showed a positive correlation with baseline HBV DNA levels (r = 0.625, P < 0.001). The mean HBsAg titers after ETV treatment were significantly lower than the baseline titers (P ranges from 0.025 to 0.000,000,6). The HBsAg reduction rate during the 1^st year was greater compared to after 1 year of treatment (P < 0.05). Multivariate test showed that hepatitis B e antigen (HBeAg) seroclearance and/or HBsAg reduction ≥0.5 log₁₀ IU/ml at 6 months had a high negative predictive value (96.77%) for HBsAg seroclearance (P = 0.002, P = 0.012, respectively).

Conclusions:

The HBsAg reduction rate during the 1^st year was greater than that after 1 year of treatment. Further, HBeAg status and HBsAg levels at month 6 are the optimal factors for the early prediction of HBsAg seroclearance after long-term ETV therapy in CHB patients.

Comparison of FIB-4 index and aspartate aminotransferase to platelet ratio index on carcinogenesis in chronic hepatitis B treated with entecavir

Aims: We sought to compare the effects of FIB-4 index and aspartate aminotransferase to platelet ratio index (APRI) on hepatocellular carcinoma (HCC) incidence in chronic hepatitis B (CHB) patients undergoing entecavir (ETV) therapy.

Patient and methods: A total of 338 nucleosides analogue therapy naïve CHB patients initially treated with ETV were analyzed. The optimal cutoff points in each continuous variable were determined by receiver operating curve (ROC) analysis. The effects of FIB-4 index and APRI on HCC incidence were compared using time-dependent ROC analysis and factors linked to HCC incidence were also examined using univariate and multivariate analyses.

Results: There were 215 males and 123 females with the median age of 52 years and the median baseline HBV-DNA level of 6.6 log copies/ml. The median follow-up interval after the initiation of ETV therapy was 4.99 years. During the follow-up period, 33 patients (9.8%) developed HCC. The 3-, 5- 7-year cumulative HCC incidence rates in all cases were 4.4%, 9.2% and 13.5%, respectively. In the multivariate analysis, FIB-4 index revealed to be an independent predictor associated with HCC incidence, while APRI was not. In the time-dependent ROC analyses for all cases and for all subgroups analyses stratified by viral status or cirrhosis status, all area under the ROCs in each time point (2-, 3-, 4-, 5-, 6-, and 7-year) of FIB-4 index were higher than those of APRI.

Conclusion: FIB-4 index rather than APRI can be a useful predictor associated with HCC development for CHB patients undergoing ETV therapy.

Identification of UQCRB as an oxymatrine recognizing protein using a T7 phage display screen

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora flavescens Aiton (Radix Sophorae Flavescentis, Kushen) is used in traditional Chinese medicine to treat chronic hepatitis B (CHB), and has the ability to clear heat and dampness from the body. Oxymatrine is one of the major bioactive compounds extracted from Sophora flavescens Aiton and constitutes more than 90% of the oxymatrine injection commonly used for CHB treatment in clinics in China.

AIM OF THE STUDY

We aim to analyze the protein binding target of oxymatrine in treating CHB by screening a T7 phage display cDNA library of human CHB and examine the biochemistry of protein-ligand binding between oxymatrine and its ligands.

MATERIALS AND METHODS

A T7 phage cDNA library of human CHB was biopanned by affinity selection using oxymatrine as bait. The interaction of oxymatrine with its candidate binding protein was investigated by affinity assay, molecular docking, Isothermal Titration Calorimetry (ITC) and Surface Plasmon Resonance (SPR).

RESULTS

A library of potential oxymatrine binding peptides was generated. Ubiquinol-cytochrome c reductase binding protein (UQCRB) was one of the candidate binding proteins of oxymatrine. UQCRB-displaying T7 phage binding numbers in the oxymatrine group were significantly higher than that in the control group, biotin group, and matrine group (p<0.05 or p<0.01). Three-dimensional structure modeling of the UQCRB with oxymatrine showed that their binding interfaces matched and oxymatrine inserted into a deeper pocket of UQCRB, which mainly involved amino acid residues Tyr21, Arg33, Tyr83, Glu84, Asp86, Pro88, and Glu91. The binding affinity constant (Kb) from SPR was 4.2mM. The Kb from ITC experiment was 3.9mM and stoichiometry was fixed as 1, which fit very well with the result of SPR. The binding of oxymatrine to UQCRB was driven by strong enthalpy forces such as hydrogen bonds and polar interactions as the heat released was about 157kcal/mol and ΔG was less than zero.

CONCLUSIONS

In this study, using the T7 phage display system, we have identified UQCRB as a direct binding protein of oxymatrine. Furthermore, the specificity and molecular interaction of oxymatrine with UQCRB were also determined. The binding of UQCRB to oxymatrine suggests that UQCRB is a potential target of oxymatrine in treating CHB. These results provide new understanding into the mechanism of oxymatrine and insights into the strategy on the treatment of CHB.

Toward Elimination of Hepatitis B Virus Using Novel Drugs, Approaches, and Combined Modalities

Hepatitis B virus (HBV) causes significant morbidity and mortality worldwide. The majority of chronically infected individuals do not achieve a functional and complete cure. Treated persons who achieve a long-term sustained virologic response (undetectable HBV DNA), are still at high risk of developing morbidity and mortality from liver complications. This review focuses on novel, mechanistically diverse anti-HBV therapeutic strategies currently in development or in clinical evaluation, and highlights new combination strategies that may contribute to full elimination of HBV DNA and covalently closed circular DNA from the infected liver, leading to a complete cure of chronic hepatitis B.

A predictive model for carcinogenesis in patients with chronic hepatitis B undergoing entecavir therapy and its validation

We created a model to predict the development of liver carcinogenesis in patients with chronic hepatitis B (CHB) undergoing entecavir (ETV) therapy and to validate the accuracy using an independent dataset.A total of 328 CHB subjects were analyzed. Subjects were randomly assigned into 2 groups: the training group (n = 164) and the validation group (n = 164). Using data from the training group, we built a predictive model for liver carcinogenesis by performing univariate and multivariate analyses using variables associated with liver carcinogenesis. We subsequently assessed the applicability of the constructed model in the validation group.The median (range) follow-up periods in the training and the validation groups were 5.03 years (1.03-9.98) and 4.84 years (1.10-9.97), respectively. The proportion of hepatitis B virus-DNA at 24 weeks <1.9 log IU/mL in the training group was 70.7% (116/164), while that in the validation group was 71.3% (117/164). For the entire cohort (n = 328), the median alpha-fetoprotein (AFP) value at 24 weeks (3.45 ng/mL; range, 0.9-102.7 ng/mL) significantly decreased compared to the baseline values (5.55 ng/mL; range, 0.9-1039.5 ng/mL), while the median alanine aminotransferase (ALT) value at 24 weeks (24 IU/mL; range, 6-251 IU/mL) also significantly decreased compared to baseline values (57 IU/mL; range, 7-1450 IU/mL). During the observation period, hepatocellular carcinoma (HCC) developed in 15 (9.1%) patients in the training group and in 17 (10.4%) patients in the validation group. The 3- and 5-year cumulative HCC incidence rates in the entire cohort were 4.48% and 9.52%, respectively. In the multivariate analysis of the training group, age ≥54 years (P = 0.0273), ALT level at 24 weeks (P = 0.0456), and AFP at 24 weeks (P = 0.0485) were found to be significant predictors linked to HCC. Using these independent predictors, the risk for HCC development was well stratified in the validation group (overall significance, P < 0.0001). Similar results were observed in subgroup analyses of patients with or without cirrhosis and HBe antigen positivity.In conclusion, our predictive model was well verified; hence, it may be a promising model for the prediction of the development of liver carcinogenesis in CHB patients undergoing ETV therapy.

Detection of Anti-Hepatitis B Virus Drug Resistance Mutations Based on Multicolor Melting Curve Analysis

Detection of anti-hepatitis B virus (HBV) drug resistance mutations is critical for therapeutic decisions for chronic hepatitis B virus infection. We describe a real-time PCR-based assay using multicolor melting curve analysis (MMCA) that could accurately detect 24 HBV nucleotide mutations at 10 amino acid positions in the reverse transcriptase region of the HBV polymerase gene. The two-reaction assay had a limit of detection of 5 copies per reaction and could detect a minor mutant population (5% of the total population) with the reverse transcriptase M204V amino acid mutation in the presence of the major wild-type population when the overall concentration was 10⁴ copies/μl. The assay could be finished within 3 h, and the cost of materials for each sample was less than $10. Clinical validation studies using three groups of samples from both nucleos(t)ide analog-treated and -untreated patients showed that the results for 99.3% (840/846) of the samples and 99.9% (8,454/8,460) of the amino acids were concordant with those of Sanger sequencing of the PCR amplicon from the HBV reverse transcriptase region (PCR Sanger sequencing). HBV DNA in six samples with mixed infections consisting of minor mutant subpopulations was undetected by the PCR Sanger sequencing method but was detected by MMCA, and the results were confirmed by coamplification at a lower denaturation temperature-PCR Sanger sequencing. Among the treated patients, 48.6% (103/212) harbored viruses that displayed lamivudine monoresistance, adefovir monoresistance, entecavir resistance, or lamivudine and adefovir resistance. Among the untreated patients, the Chinese group had more mutation-containing samples than did the Pakistani group (3.3% versus 0.56%). Because of its accuracy, rapidness, wide-range coverage, and cost-effectiveness, the real-time PCR assay could be a robust tool for the detection if anti-HBV drug resistance mutations in resource-limited countries.

New horizon for radical cure of chronic hepatitis B virus infection

About 250 to 350 million people worldwide are chronically infected with hepatitis B virus (HBV), and about 700000 patients per year die of HBV-related cirrhosis or hepatocellular carcinoma (HCC). Several anti-viral agents, such as interferon and nucleos(t)ide analogues (NAs), have been used to treat this disease. NAs especially have been shown to strongly suppress HBV replication, slowing the progression to cirrhosis and the development of HCC. However, reactivation of HBV replication often occurs after cessation of treatment, because NAs alone cannot completely remove covalently-closed circular DNA (cccDNA), the template of HBV replication, from the nuclei of hepatocytes. Anti-HBV immune responses, in conjunction with interferon-γ and tumor necrosis factor-α, were found to eliminate cccDNA, but complete eradication of cccDNA by immune response alone is difficult, as shown in patients who recover from acute HBV infection but often show long-term persistence of small amounts of HBV-DNA in the blood. Several new drugs interfering with the life cycle of HBV in hepatocytes have been developed, with drugs targeting cccDNA theoretically the most effective for radical cure of chronic HBV infection. However, the safety of these drugs should be extensively examined before application to patients, and combinations of several approaches may be necessary for radical cure of chronic HBV infection.

Hepatitis B virus resistance substitutions: long-term analysis by next-generation sequencing

HBV phylogenetics and resistance-associated mutations (RAMs) were surveyed by next-generation sequencing of 21 longitudinal samples from seven patients entering antiviral therapy. The virus populations were dominated by a few abundant lineages that coexisted with substantial numbers of low-frequency variants. A few low-frequency RAMs were observed before treatment, but new ones emerged, and their frequencies increased during therapy. Together, these results support the idea that chronic HBV infection is dominated by a few virus lineages and that an accompanying plethora of diverse, low-frequency variants may function as a reservoir that potentially contribute to viral genetic plasticity, potentially affecting patient outcome.

Study on 2-arylthio-5-iodo pyrimidine derivatives as novel nonnucleoside inhibitors against hepatitis B virus DNA replication

BACKGROUND

Novel nonnucleoside hepatitis B virus inhibitors have been recently developed for the reason of drug-resistant mutations and adverse effects of nucleoside analogs. In this study, two series of 2-arylthio-5-iodo pyrimidine analogs were firstly reported as potential anti-HBV agents.

METHODOLOGY

Target compounds were prepared according to two high-yielded synthetic routes, and their anti-HBV activities were evaluated on Hep2.2.15 and HepAD38 cell lines, respectively. To probe the mechanism of active agents, a cell-based (Huh-7) study of biochemical markers (e.g., HBeAg, HBsAg, intracellular HBV DNA and pgRNA) was performed. Furthermore, the pharmacophore models were constructed for future optimization of lead compounds.

CONCLUSION

2-Arylthio-5-iodo pyrimidine derivatives firstly proved to be effective against HBV, which paves the way for future development of nonnucleoside anti-HBV agents.