Pathogenesis of hepatitis B virus infection

Association of HLA-G 3'UTR polymorphisms with hepatitis B virus infection in Tunisian population

Hepatitis B virus (HBV) infection is a major public health burden. The mechanisms of immune evasion during chronic HBV (CHB) infection are poorly understood. Human leukocyte antigen (HLA)-G, an immune checkpoint molecule, plays a crucial role in the tolerance mechanisms of various infectious diseases. The 3' untranslated region (3'UTR), including the HLA-G + 3142 C > G polymorphism (rs1063320) and the 14-pb Ins/Del (rs66554220) has been strongly suggested to influence HLA-G expression. This study conducted a case-control analysis to evaluate the potential correlation between the HLA-G + 3142 C > G polymorphism and HBV infection outcome in a Tunisian cohort. The HLA-G + 3142 C > G polymorphism was analysed by PCR-RFLP in 242 patients with chronic HBV infection (116 males and 126 females), 241 healthy controls (116 males and 125 females), and 100 spontaneously resolved subjects (52 males and 48 females). Patients with chronic HBV infection showed a higher frequency of the + 3142G allele compared to healthy controls and spontaneously resolved subjects (p = 0.001 and p = 0.002, respectively). An association between the + 3142G allele and high HBV DNA levels was observed when HBV patients were stratified based on their HBV DNA levels (p = 0.016). Furthermore, the dominant model (GG + GC vs CC) was associated with liver function parameters, including AST, ALT, and high HBV DNA levels (p = 0.04, p < 0.001 and p = 0.002, respectively). However, there was no significant association found between this polymorphism and the fibrosis stage (p = 0.32). The haplotype analysis, using a subset of previously published data on the HLA-G 14-pb Ins/Del polymorphism, revealed an association between the Ins/G haplotype and chronic HBV infection (H1: InsG, p < 0.001). Our findings suggest that the + 3142G allele is a risk factor for the persistence and progression of HBV infection, while the + 3142C allele serves as a protective allele associated with the spontaneous resolution of the infection. Additionally, the HLA-G 3'UTR haplotype Ins/G is associated with chronic HBV infection in the Tunisian population.

mRNA-LNP vaccine-induced CD8+ T cells protect mice from lethal SARS-CoV-2 infection in the absence of specific antibodies

The role of CD8+ T cells in SARS-CoV-2 pathogenesis or mRNA-LNP vaccine-induced protection from lethal COVID-19 is unclear. Using mouse-adapted SARS-CoV-2 virus (MA30) in C57BL/6 mice, we show that CD8+ T cells are unnecessary for the intrinsic resistance of female or the susceptibility of male mice to lethal SARS-CoV-2 infection. Also, mice immunized with a di-proline prefusion-stabilized full-length SARS-CoV-2 Spike (S-2P) mRNA-LNP vaccine, which induces Spike-specific antibodies and CD8+ T cells specific for the Spike-derived VNFNFNGL peptide, are protected from SARS-CoV-2 infection-induced lethality and weight loss, while mice vaccinated with mRNA-LNPs encoding only VNFNFNGL are protected from lethality but not weight loss. CD8+ T cell depletion ablates protection in VNFNFNGL but not in S-2P mRNA-LNP-vaccinated mice. Therefore, mRNA-LNP vaccine-induced CD8+ T cells are dispensable when protective antibodies are present but essential for survival in their absence. Hence, vaccine-induced CD8+ T cells may be critical to protect against SARS-CoV-2 variants that mutate epitopes targeted by protective antibodies.

Serosusceptibility and hesitancy for booster HBV vaccination among health care workers in Italy: A cross-sectional study

BACKGROUND

Health care workers (HCWs) are at increased risk of exposure to hepatitis B virus (HBV). The most effective prevention measure is vaccination, with a serum hepatitis B surface antibody (HBsAb) titre > 10 mIU/ml considered protective. To date, the sociodemographic and occupational characteristics related to HBV serosusceptibility and factors associated with booster hesitancy remain unclear. Therefore, this study aimed to identify factors associated with maintaining a protective HBsAb titre in a large sample of HCWs and to evaluate factors potentially associated with hesitancy towards vaccine boosters.

METHODS

A cross-sectional study was conducted among HCWs who underwent a health surveillance visit between 2017 and 2022. If the serum HBsAb titre was < 10 MIU/ml, a vaccine booster dose was offered. Based on their willingness to be vaccinated, employees were classified into three groups: acceptance, hesitation, and refusal. Uni- and multivariable analyses were performed to assess the association of demographic and occupational characteristics with serosusceptibility and attitudes towards vaccination.

RESULTS

A total of 1632 (27%) employees were shown to be nonimmune. A lower median age and being a physician were significantly associated with a protective HBsAb titre. A total of 706 nonimmune employees (43.3%) accepted the vaccination, 865 (53%) hesitated, and 61 (3.7%) refused. The median age of those who refused vaccination was significantly higher than that of those who hesitated and those who were vaccinated. Acceptance of vaccination was significantly higher among nurses, while nurse aides hesitated more; among nonmedical graduate staff both hesitation and refusal were higher than expected. In the multivariable analysis, higher age, female sex, and employment as an allied health care professional were shown to be significantly associated with hesitation/refusal, while being born abroad turned out to be protective.

CONCLUSIONS

Our study showed that approximately a quarter of HCWs were not immune to HBV infection, and of these, more than half were hesitant towards or refused the booster dose. The risk of hesitation/refusal was higher with age in women and among allied health care staff. Based on these findings, further studies are needed to prospectively evaluate HBV seroprevalence, vaccination adherence, factors associated with hesitancy, and the effectiveness of health surveillance strategies in a high-risk population susceptible to infection.

The impact of HBx protein on mitochondrial dynamics and associated signaling pathways strongly depends on the hepatitis B virus genotype

Chronic hepatitis B virus (HBV) infections are strongly associated with liver cirrhosis, inflammation, and hepatocellular carcinoma. In this context, the viral HBx protein is considered as a major factor influencing HBV-associated pathogenesis through deregulation of multiple cellular signaling pathways and is therefore a potential target for prognostic and therapeutic applications. However, HBV-associated pathogenesis differs significantly between genotypes, with the relevant factors and in particular the contribution of the genetic diversity of HBx being largely unknown. To address this question, we studied the specific genotype-dependent impact of HBx on cellular signaling pathways, focusing in particular on morphological and functional parameters of mitochondria. To exclusively investigate the impact of HBx of different genotypes on integrity and function of mitochondria in the absence of additional viral factors, we overexpressed HBx in Huh7 or HepG2 cells. Key signaling pathways were profiled by kinome analysis and correlated with expression levels of mitochondrial and pathogenic markers. Conclusively, HBx of genotypes A and G caused strong disruption of mitochondrial morphology alongside an induction of PTEN-induced putative kinase 1/Parkin-mediated mitophagy. These effects were only moderately dysregulated by genotypes B and E, whereas genotypes C and D exhibit an intermediate effect in this regard. Accordingly, changes in mitochondrial membrane potential and elevated reactive oxygen species production were associated with the HBx-mediated dysfunction among different genotypes. Also, genotype-related differences in mitophagy induction were identified and indicated that HBx-mediated changes in the mitochondria morphology and function strongly depend on the genotype. This indicates a relevant role of HBx in the process of genotype-dependent liver pathogenesis of HBV infections and reveals underlying mechanisms.IMPORTANCEThe hepatitis B virus is the main cause of chronic liver disease worldwide and differs in terms of pathogenesis and clinical outcome among the different genotypes. Furthermore, the viral HBx protein is a known factor in the progression of liver injury by inducing aberrant mitochondrial structures and functions. Consequently, the selective removal of dysfunctional mitochondria is essential to maintain overall cellular homeostasis and cell survival. Consistent with the intergenotypic difference of HBV, our data reveal significant differences regarding the impact of HBx of different genotypes on mitochondrial dynamic and function and thereby on radical oxygen stress levels within the cell. We subsequently observed that the induction of mitophagy differs significantly across the heterogenetic HBx proteins. Therefore, this study provides evidence that HBx-mediated changes in the mitochondria dynamics and functionality strongly depend on the genotype of HBx. This highlights an important contribution of HBx in the process of genotype-dependent liver pathogenesis.

A novel, small anti-HBV compound reduces HBsAg and HBV-DNA by destabilizing HBV-RNA

BACKGROUND

Currently, standard treatments for chronic hepatitis B such as nucleos(t)ide analogs (NAs), effectively reduce hepatitis B virus (HBV) loads but rarely result in a functional cure (defined as sustained HBsAg loss). We report the discovery of a novel, 4-pyridone compound, SAG-524, a potent and orally bioavailable small molecule inhibitor of HBV replication.

METHODS

The antiviral characteristics and selectivity of SAG-524 and its derivative compound against HBV were evaluated in HBV-infection assays and HBV-infected chimeric urokinase-type plasminogen activator/severe combined immunodeficiency mice with humanized livers (PXB mice), alone or in combination with entecavir. Toxicity studies were conducted in mice and monkeys.

RESULTS

SAG-524 reduced HBV-DNA (IC50 = 0.92 nM) and HBsAg (IC50 = 1.4 nM) in the supernatant of the HepG2.2.15 cells. SAG-524 selectively destabilized HBV-RNA via PAPD5, but not GAPDH or albumin mRNA, by shortening the poly(A) tail. PAPD5 may also be involved in HBV regulation via ELAVL1. In a study of HBV-infected PXB mice, SAG-524 produced potent reductions of serum HBsAg and HBcrAg, and the minimum effective dose was estimated to be 6 mg/kg/day. The combination therapy with entecavir greatly reduced HBsAg and cccDNA in the liver due to reduction of human hepatocytes with good tolerability. Administration of SAG-524 to monkeys, up to 1000 mg/kg/day for two weeks, led to no significant toxicity, as determined by blood tests and pathological images.

CONCLUSIONS

We have identified SAG-524 as novel and orally bioavailable HBV-RNA destabilizers which can reduce HBsAg and HBV-DNA levels, and possibly contribute a functional cure.

Leveraging stem cells to combat hepatitis: a comprehensive review of recent studies

Hepatitis is a significant global public health concern, with viral infections being the most common cause of liver inflammation. Antiviral medications are the primary treatments used to suppress the virus and prevent liver damage. However, the high cost of these drugs and the lack of awareness and stigma surrounding the disease create challenges in managing hepatitis. Stem cell therapy has arisen as a promising therapeutic strategy for hepatitis by virtue of its regenerative and immunomodulatory characteristics. Stem cells have the exceptional capacity to develop into numerous cell types and facilitate tissue regeneration, rendering them a highly promising therapeutic avenue for hepatitis. In animal models, stem cell therapy has demonstrated worthy results by reducing liver inflammation and improving liver function. Furthermore, clinical trials have been undertaken to assess the safety and effectiveness of stem cell therapy in individuals with hepatitis. This review aims to explore the involvement of stem cells in treating hepatitis and highlight the findings from studies conducted on both animals and humans. The objective of this review is to primarily concentrate on the ongoing and future clinical trials that assess the application of stem cell therapy in the context of hepatitis, including the transplantation of autologous bone marrow-derived stem cells, human induced pluripotent stem cells, and other mesenchymal stem cells. In addition, this review will explore the potential merits and constraints linked to stem cell therapy for hepatitis, as well as its prospective implications in the management of this disease.

Three-Dimensional Structure of Novel Liver Cancer Biomarker Liver Cancer-Specific Serine Protease Inhibitor Kazal (LC-SPIK) and Its Performance in Clinical Diagnosis of Hepatocellular Carcinoma (HCC)

LC-SPIK is a liver cancer-specific isoform of Serine Protease Inhibitor Kazal and has been proposed as a new biomarker for the detection of HCC given its unique 3D structure, which differs from normal pancreatic SPIK. An ELISA technology based on its unique structure was developed to use LC-SPIK as an effective biomarker for the clinical diagnosis of HCC. AFP, the most widely used biomarker for HCC surveillance currently, suffers from poor clinical performance, especially in the detection of early-stage HCC. In one case-control study, which included 164 HCC patients and 324 controls, LC-SPIK had an AUC of 0.87 compared to only 0.70 for AFP in distinguishing HCC from liver disease controls (cirrhosis, HBV/HCV). LC-SPIK also performed significantly better than AFP for the 81 patients with early-stage HCC (BCLC stage 0 and A), with an AUC of 0.85 compared to only 0.61 for AFP. Cirrhosis is the major risk factor for HCC; about 80% of patients with newly diagnosed HCC have preexisting cirrhosis. LC-SPIK's clinical performance was also studied in HCC patients with viral and non-viral cirrhosis, including cirrhosis caused by metabolic dysfunction-associated steatotic liver disease (MASLD) and alcoholic liver disease (ALD). In a total of 163 viral cirrhosis patients with 93 HCC patients (50 early-stage), LC-SPIK had an AUC of 0.85, while AFP had an AUC of 0.70. For patients with early-stage HCC, LC-SPIK had a similar AUC of 0.83, while AFP had an AUC of only 0.60. For 120 patients with nonviral cirrhosis, including 62 HCC (23 early-stage) patients, LC-SPIK had an AUC of 0.84, while AFP had an AUC of only 0.72. For the 23 patients with early-stage HCC, LC-SPIK had a similar AUC of 0.83, while the AUC for AFP decreased to 0.65. All these results suggest that LC-SPIK exhibits significantly better performance in the detection of HCC than AFP in all etiologies of liver diseases. In addition, LC-SPIK accurately detected the presence of HCC in 71-91% of HCC patients with false-negative AFP test results in viral-associated HCC and non-viral-associated HCC.

Liver injury in COVID-19: an insight into pathobiology and roles of risk factors

COVID-19 is a complex disease that can lead to fatal respiratory failure with extrapulmonary complications, either as a direct result of viral invasion in multiple organs or secondary to oxygen supply shortage. Liver is susceptible to many viral pathogens, and due to its versatile functions in the body, it is of great interest to determine how hepatocytes may interact with SARS-CoV-2 in COVID-19 patients. Liver injury is a major cause of death, and SARS-CoV-2 is suspected to contribute significantly to hepatopathy. Owing to the lack of knowledge in this field, further research is required to address these ambiguities. Therefore, we aimed to provide a comprehensive insight into host-virus interactions, underlying mechanisms, and associated risk factors by collecting results from epidemiological analyses and relevant laboratory experiments. Backed by an avalanche of recent studies, our findings support that liver injury is a sequela of severe COVID-19, and certain pre-existing liver conditions can also intensify the morbidity of SARS-CoV-2 infection in synergy. Notably, age, sex, lifestyle, dietary habits, coinfection, and particular drug regimens play a decisive role in the final outcome and prognosis as well. Taken together, our goal was to unravel these complexities concerning the development of novel diagnostic, prophylactic, and therapeutic approaches with a focus on prioritizing high-risk groups.

Review of Related Factors for Persistent Risk of Hepatitis B Virus-Associated Hepatocellular Carcinoma

Chronic hepatitis B virus (HBV) infection is the largest global cause of hepatocellular carcinoma (HCC). Current HBV treatment options include pegylated interferon-alpha and nucleos(t)ide analogues (NAs), which have been shown to be effective in reducing HBV DNA levels to become undetectable. However, the literature has shown that some patients have persistent risk of developing HCC. The mechanism in which this occurs has not been fully elucidated. However, it has been discovered that HBV's covalently closed circular DNA (cccDNA) integrates into the critical HCC driver genes in hepatocytes upon initial infection; additionally, these are not targets of current NA therapies. Some studies suggest that HBV undergoes compartmentalization in peripheral blood mononuclear cells that serve as a sanctuary for replication during antiviral therapy. The aim of this review is to expand on how patients with HBV may develop HCC despite years of HBV viral suppression and carry worse prognosis than treatment-naive HBV patients who develop HCC. Furthermore, HCC recurrence after initial surgical or locoregional treatment in this setting may cause carcinogenic cells to behave more aggressively during treatment. Curative novel therapies which target the life cycle of HBV, modulate host immune response, and inhibit HBV RNA translation are being investigated.

Effects of co-infection with Clonorchis sinensis on T cell exhaustion levels in patients with chronic hepatitis B

To investigate the effects of co-infection with Clonorchis sinensis (C. sinensis) on T cell exhaustion levels in patients with chronic hepatitis B, we enrolled clinical cases in this study, including the patients with concomitant C. sinensis and HBV infection. In this study, we detected inhibitory receptors and cytokine expression in circulating CD4+ and CD8+ T cells by flow cytometry. PD-1 and TIM-3 expression levels were significantly higher on CD4+ T and CD8+ T cells from co-infected patients than on those from the HBV patients. In addition, CD4+ T cells and CD8+ T cells function were significantly inhibited by C. sinensis and HBV co-infection compared with HBV single infection, secreting lower levels of Interferon gamma (IFN-γ), Interleukin-2 (IL-2), and TNF-α. Our current results suggested that C. sinensis co-infection could exacerbate T cell exhaustion in patients with chronic hepatitis B. PD-1 and TIM-3 could be novel biomarkers for T cell exhaustion in patients with Clonorchis sinensis and chronic hepatitis B co-infection. Furthermore, it may be one possible reason for the weaker response to antiviral therapies and the chronicity of HBV infection in co-infected patients. We must realize the importance of C. sinensis treatment for HBV-infected patients. It might provide useful information for clinical doctors to choose the right treatment plans.

The novel mechanism facilitating chronic hepatitis B infection: immunometabolism and epigenetic modification reprogramming

Hepatitis B Virus (HBV) infections pose a global public health challenge. Despite extensive research on this disease, the intricate mechanisms underlying persistent HBV infection require further in-depth elucidation. Recent studies have revealed the pivotal roles of immunometabolism and epigenetic reprogramming in chronic HBV infection. Immunometabolism have identified as the process, which link cell metabolic status with innate immunity functions in response to HBV infection, ultimately contributing to the immune system's inability to resolve Chronic Hepatitis B (CHB). Within hepatocytes, HBV replication leads to a stable viral covalently closed circular DNA (cccDNA) minichromosome located in the nucleus, and epigenetic modifications in cccDNA enable persistence of infection. Additionally, the accumulation or depletion of metabolites not only directly affects the function and homeostasis of immune cells but also serves as a substrate for regulating epigenetic modifications, subsequently influencing the expression of antiviral immune genes and facilitating the occurrence of sustained HBV infection. The interaction between immunometabolism and epigenetic modifications has led to a new research field, known as metabolic epigenomics, which may form a mutually reinforcing relationship with CHB. Herein, we review the recent studies on immunometabolism and epigenetic reprogramming in CHB infection and discuss the potential mechanisms of persistent HBV infection. A deeper understanding of these mechanisms will offer novel insights and targets for intervention strategies against chronic HBV infection, thereby providing new hope for the treatment of related diseases.

Therapeutic vaccination with lentiviral vector in HBV-persistent mice and two inactive HBsAg carriers

BACKGROUND & AIMS

Immunotherapy for chronic hepatitis B virus (HBV) infection has not yet demonstrated sufficient efficacy. We developed a non-integrative lentiviral-vectored therapeutic vaccine for chronic hepatitis B and tested its antiviral effects in HBV-persistent mice and two inactive HBsAg carriers.

METHODS

Lentiviral vectors (LVs) encoding the core, preS1, or large HBsAg (LHBs) proteins of HBV were evaluated for immunogenicity in HBV-naïve mice and therapeutic efficacy in a murine model of chronic HBV infection. In addition, two inactive HBsAg carriers each received two doses of 5×107 transduction units (TU) or 1×108 TU of lentiviral-vectored LHBs (LV-LHBs), respectively. The endpoints were safety, LHBs-specific T-cell responses, and serum HBsAg levels during a 24-week follow-up.

RESULTS

In the mouse models, LV-LHBs was the most promising in eliciting robust antigen-specific T cells and in reducing the levels of serum HBsAg and viral load. By the end of the 34-week observation period, six out of ten (60%) HBV-persistent mice vaccinated with LV-LHBs achieved serum HBsAg loss and significant depletion of HBV-positive hepatocytes in the liver. In the two inactive HBsAg carriers, vaccination with LV-LHBs induced a considerable increase in the number of peripheral LHBs-specific T cells in one patient, and a weak but detectable response in the other, accompanied by a sustained reduction of HBsAg (-0.31 log10 IU/ml and -0.46 log10 IU/ml, respectively) from baseline to nadir.

CONCLUSIONS

A lentiviral-vectored therapeutic vaccine for chronic HBV infection demonstrated the potential to improve HBV-specific T-cell responses and deplete HBV-positive hepatocytes, leading to a sustained loss or reduction of serum HBsAg.

IMPACT AND IMPLICATIONS

Chronic HBV infection is characterized by an extremely low number and profound hypo-responsiveness of HBV-specific T cells. Therapeutic vaccines are designed to improve HBV-specific T-cell responses. We show that immunization with a lentiviral-vectored therapeutic HBV vaccine was able to expand HBV-specific T cells in vivo, leading to reductions of HBV-positive hepatocytes and serum HBsAg.

Hepatitis B Virus Modulated Transcriptional Regulatory Map of Hepatic Cellular MicroRNAs

Hepatitis B virus (HBV) is an enveloped, hepatotropic, noncytopathic virus with a partially double-stranded DNA genome. It infects hepatocytes and is associated with progression to liver fibrosis and cirrhosis, culminating in hepatocellular carcinoma (HCC), accounting for 55% of total HCC cases. MicroRNAs (miRNAs) regulated by HBV play an important role in these pathologies. Mapping the miRNAs responsive to HBV and HBV-specific proteins, including HBV X protein (HBx) that harbor the majority of HBV-human protein interactions, could aid accelerate the diagnostics and therapeutics innovation against the infection and associated diseases. With this in mind, we used a unique annotation strategy whereby we first amassed 362 mature HBV responsive-human Differentially Expressed miRNAs (HBV-hDEmiRs). The core experimentally-validated messenger RNA targets of the HBV-hDEmiRs were mostly associated with viral infections and hepatic inflammation processes. Moreover, our annotation strategy enabled the characterization of HBx-dependent/independent HBV-hDEmiRs as a tool for evaluation of the impact of HBx as a therapeutic target. Bioinformatics analysis of the HBV-human protein-protein interactome revealed new insights into the transcriptional regulatory network of the HBV-hDEmiRs. We performed a comparative analysis of data on miRNAs gathered from HBV infected cell line studies and from tissue studies of fibrosis, cirrhosis, and HCC. Accordingly, we propose hsa-miR-15a-5p that is downregulated by multiple HBV proteins, including HBx, as a potential biomarker of HBV infection, and its progression to HCC. In all, this study underscores (1) the complexity of miRNA regulation in response to HBV infection and its progression into other liver pathologies and (2) provides a regulatory map of HBV-hDEmiRs and the underlying mechanisms modulating their expression through a cross talk between HBV viral proteins and human transcription factors.

Integrated vector genomes may contribute to long-term expression in primate liver after AAV administration

The development of liver-based adeno-associated virus (AAV) gene therapies is facing concerns about limited efficiency and durability of transgene expression. We evaluated nonhuman primates following intravenous dosing of AAV8 and AAVrh10 vectors for over 2 years to better define the mechanism(s) of transduction that affect performance. High transduction of non-immunogenic transgenes was achieved, although expression declined over the first 90 days to reach a lower but stable steady state. More than 10% of hepatocytes contained single nuclear domains of vector DNA that persisted despite the loss of transgene expression. Greater reductions in vector DNA and RNA were observed with immunogenic transgenes. Genomic integration of vector sequences, including complex concatemeric structures, were detected in 1 out of 100 cells at broadly distributed loci that were not in proximity to genes associated with hepatocellular carcinoma. Our studies suggest that AAV-mediated transgene expression in primate hepatocytes occurs in two phases: high but short-lived expression from episomal genomes, followed by much lower but stable expression, likely from integrated vectors.

Potent broadly neutralizing antibody VIR-3434 controls hepatitis B and D virus infection and reduces HBsAg in humanized mice

BACKGROUND & AIMS

Chronic hepatitis B is a global public health problem, and coinfection with hepatitis delta virus (HDV) worsens disease outcome. Here, we describe a hepatitis B virus (HBV) surface antigen (HBsAg)-targeting monoclonal antibody (mAb) with the potential to treat chronic hepatitis B and chronic hepatitis D.

METHODS

HBsAg-specific mAbs were isolated from memory B cells of HBV vaccinated individuals. In vitro neutralization was determined against HBV and HDV enveloped with HBsAg representing eight HBV genotypes. Human liver-chimeric mice were treated twice weekly with a candidate mAb starting 3 weeks post HBV inoculation (spreading phase) or during stable HBV or HBV/HDV coinfection (chronic phase).

RESULTS

From a panel of human anti-HBs mAbs, VIR-3434 was selected and engineered for pre-clinical development. VIR-3434 targets a conserved, conformational epitope within the antigenic loop of HBsAg and neutralized HBV and HDV infection with higher potency than hepatitis B immunoglobulins in vitro. Neutralization was pan-genotypic against strains representative of HBV genotypes A-H. In the spreading phase of HBV infection in human liver-chimeric mice, a parental mAb of VIR-3434 (HBC34) prevented HBV dissemination and the increase in intrahepatic HBV RNA and covalently closed circular DNA. In the chronic phase of HBV infection or co-infection with HDV, HBC34 treatment decreased circulating HBsAg by >1 log and HDV RNA by >2 logs.

CONCLUSIONS

The potently neutralizing anti-HBs mAb VIR-3434 reduces circulating HBsAg and HBV/HDV viremia in human liver-chimeric mice. VIR-3434 is currently in clinical development for treatment of patients with chronic hepatitis B or D.

IMPACT AND IMPLICATIONS

Chronic infection with hepatitis B virus and co-infection with hepatitis D virus place approximately 290 million individuals worldwide at risk of severe liver disease and cancer. Available treatments result in low rates of functional cure or require lifelong therapy that does not eliminate the risk of liver disease. We isolated and characterized a potent human antibody that neutralizes hepatitis B and D viruses and reduces infection in a mouse model. This antibody could provide a new treatment for patients with chronic hepatitis B and D.

Anti-HBc: a significant host predictor of spontaneous HBsAg seroclearance in chronic hepatitis B patients - a retrospective longitudinal study

BACKGROUND AND AIM

In chronic hepatitis B infection (CHB), seroclearance of hepatitis B surface antigen (HBsAg) is associated with favourable clinical outcomes compared to those with persistent HBsAg seropositivity, and thus considered as a desired treatment endpoint. This current study explores the possibility of serum antibody to hepatitis B core antigen (anti-HBc) as a potential predictive factor of HBsAg seroclearance.

METHODS

This is a retrospective study that analyzed the plasma samples of CHB patients using the LUMIPULSE® G1200 analyzer. The longitudinal anti-HBc level between patients who subsequently achieved HBsAg seroclearance (S-losers) and those with persistent HBsAg-positivity (controls) were compared at multiple time points before the event.

RESULTS

A total of 240 subjects (120 S-losers and 120 controls; age- and gender-matched) were included (mean age 56.42 ± 10.81, 65% male). Compared to controls, S-losers had significantly lower plasma anti-HBc levels prior to HBsAg seroclearance, with a significant trend of declining plasma anti-HBc 8-5 years prior to HBsAg seroclearance (p < 0.01), while such trend was not observed in controls. ROC curve analysis revealed that plasma anti-HBc at multiple time points before HBsAg seroclearance return AUC greater than 0.7. Plasma anti-HBc level at the cut-off value of 82.50 COI was 68.3% sensitive and 90% specific for HBsAg seroclearance within 1 year. Combining with quantitative HBsAg < 100 IU/mL, anti-HBc < 82.5 COI identified 88.2% patients who would develop HBsAg seroclearance within 1 year.

CONCLUSION

Plasma anti-HBc level began to decline 10 years prior to HBsAg seroclearance and can serve as a potential predictor for subsequent HBsAg seroclearance.

Unmet Needs in the Post-Direct-Acting Antiviral Era: Hepatocarcinogenesis After Hepatitis C Virus Eradication

Infection with chronic hepatitis C virus (HCV) is an important risk factor for hepatocellular carcinoma (HCC). Direct-acting antiviral therapy has transformed care for patients with HCV and reduces the risk of HCC. Despite HCV cure, a residual HCC risk remains in patients with advanced fibrosis and cirrhosis, with multiple mechanisms underlying subsequent hepatocarcinogenesis. Transcriptomic and proteomic signatures demonstrate the capacity for HCC risk stratification, and chemoprevention strategies are emerging. For now, pending more precise stratification, HCC surveillance of patients with cured HCV and advanced fibrosis or cirrhosis should continue.

Hepatitis B Virus Epsilon (ε) RNA Element: Dynamic Regulator of Viral Replication and Attractive Therapeutic Target

Hepatitis B virus (HBV) chronically infects millions of people worldwide, which underscores the importance of discovering and designing novel anti-HBV therapeutics to complement current treatment strategies. An underexploited but attractive therapeutic target is ε, a cis-acting regulatory stem-loop RNA situated within the HBV pregenomic RNA (pgRNA). The binding of ε to the viral polymerase protein (P) is pivotal, as it triggers the packaging of pgRNA and P, as well as the reverse transcription of the viral genome. Consequently, small molecules capable of disrupting this interaction hold the potential to inhibit the early stages of HBV replication. The rational design of such ligands necessitates high-resolution structural information for the ε-P complex or its individual components. While these data are currently unavailable for P, our recent structural elucidation of ε through solution nuclear magnetic resonance spectroscopy marks a significant advancement in this area. In this review, we provide a brief overview of HBV replication and some of the therapeutic strategies to combat chronic HBV infection. These descriptions are intended to contextualize our recent experimental efforts to characterize ε and identify ε-targeting ligands, with the ultimate goal of developing novel anti-HBV therapeutics.

Unravelling the Interplay: Exploring the Influence of Previous Hepatitis B Virus, Hepatitis A Virus, and Hepatitis E Virus Infections on Non-alcoholic Fatty Liver Disease

The intricate interplay between viral infections and non-alcoholic fatty liver disease (NAFLD) presents a fascinating and clinically significant intersection of virology and hepatology. This review article delves into the complex relationship between hepatitis B virus (HBV), hepatitis A virus (HAV), hepatitis E virus (HEV), and NAFLD. It outlines the shared mechanisms linking viral infections to NAFLD development, including their effects on lipid metabolism, immune responses, inflammation, and gut microbiota. The clinical implications of this interplay are explored, including challenges in diagnosis and management and potential therapeutic strategies. The review emphasises the need for a comprehensive understanding of these interactions as they impact disease progression, risk stratification, and treatment decisions. Furthermore, it highlights the importance of integrated approaches and personalised treatment paradigms for optimising patient care. As we navigate this intricate crossroads, the insights gained can reshape our understanding of liver health and contribute to more effective strategies for managing viral infections and NAFLD.

The hepatitis B virus pre-core protein p22 suppresses TNFα-induced apoptosis by regulating the NF-κB pathway

OBJECTIVE

Cell apoptosis is strongly associated with hepatocellular carcinoma (HCC) progress. Thus, gaining a comprehensive understanding of the virus interfering with the apoptotic process is important for the development of effective anti-tumor therapies. The objective of this study is to explore the potential involvement of HBeAg-p22 (HBV-p22) in TNFα-induced apoptosis.

METHODS

Protein expression was detected using western blot. Cell viability and apoptosis were assessed by employing Cell Counting Kit-8 (CCK8) and flow cytometry, respectively. Evaluation of protein-protein interactions was accomplished through co-immunoprecipitation and glutathione-S-transferase (GST) pull-down assays.

RESULTS

In this study, it was shown that HBV-p22 inhibited apoptosis of human hepatoma cell lines after tumor necrosis factor-alpha (TNF-α) stimulation. Mechanistically, HBV-p22 suppressed Jun N-terminal kinases (JNK) signaling and enhanced nuclear factor kappa-B (NF-κB) signaling. Moreover, HBV-p22 interacted with I-kappa B kinase α (IKKα) and increased its phosphorylation.

CONCLUSIONS

Collectively, HBV-p22, whereby the mechanism contributing to anti-apoptotic effect was regulation of the NF-κB pathway via enhancing the phosphorylation of IKKα.

Chronic viral infection compromises the quality of circulating mucosal-invariant T cells and follicular T helper cells via expression of both activating and inhibitory receptors

Chronic viral infection results in impaired immune responses rendering viral persistence. Here, we investigated the role of immune activation and compared the quality of T-cell responses in chronic HBV, HCV, and HIV infections. Cytokines were measured using a commercial Bio-plex Pro Human Cytokine Grp I Panel 17-plex kit (BioRad, Hercules, CA, USA). Inflammation was assessed by measuring an array of plasma cytokines, and peripheral CD4+ T cells including circulating Tfh cells, CD8+ T cells, and TCR iVα7.2+ MAIT cells in chronic HBV, HCV, and HIV-infected patients and healthy controls. The cells were characterized based markers pertaining to immune activation (CD69, ICOS, and CD27) proliferation (Ki67), cytokine production (TNF-α, IFN-γ) and exhaustion (PD-1). The cytokine levels and T cell phenotypes together with cell markers were correlated with surrogate markers of disease progression. The activation marker CD69 was significantly increased in CD4+ hi T cells, while CD8+ MAIT cells expressing IFN-γ were significantly increased in chronic HBV, HCV and HIV infections. Six cell phenotypes, viz., TNF-α+CD4+ lo T cells, CD69+CD8+ T cells, CD69+CD4+ MAIT cells, PD-1+CD4+ hi T cells, PD-1+CD8+ T cells, Ki67+CD4+ MAIT cells were independently associated with decelerating the plasma viral load (PVL). TNF-α levels showed a positive correlation with increase in cytokine levels and decrease in PVL. Chronic viral infection negatively impacts the quality of peripheral MAIT cells and TFH cells via expression of both activating and inhibitory receptors.

Forthcoming Developments in Models to Study the Hepatitis B Virus Replication Cycle, Pathogenesis, and Pharmacological Advancements

Hepatitis, liver cirrhosis, and hepatocellular carcinoma are all manifestations of chronic hepatitis B. Its pathogenesis and molecular mechanism remain mysterious. As medical science progresses, different models are being used to study the disease from the physiological and molecular levels. Animal models have played an unprecedented role in achieving in-depth knowledge of the disease while posing no risk of harming humans throughout the study. The scarcity of acceptable animal models has slowed progress in hepatitis B virus (HBV) research and preclinical testing of antiviral medicines since HBV has a narrow species tropism and exclusively infects humans and higher primates. The development of human chimeric mice was supported by a better understanding of the obstacles to interspecies transmission, which has substantially opened the way for HBV research in vivo and the evaluation of possible chronic hepatitis B therapeutics. Animal models are cumbersome to handle, not accessible, and expensive. Hence, it is herculean to investigate the HBV replication cycle in animal models. Therefore, it becomes essential to build a splendid in vitro cell culture system to demonstrate the mechanisms attained by the HBV for its multiplication and sustenance. We also addressed the advantages and caveats associated with different models in examining HBV.

Activation of CD4 T cells during prime immunization determines the success of a therapeutic hepatitis B vaccine in HBV-carrier mouse models

BACKGROUND & AIMS

We recently developed a heterologous therapeutic vaccination scheme (TherVacB) comprising a particulate protein prime followed by a modified vaccinia-virus Ankara (MVA)-vector boost for the treatment of HBV. However, the key determinants required to overcome HBV-specific immune tolerance remain unclear. Herein, we aimed to study new combination adjuvants and unravel factors that are essential for the antiviral efficacy of TherVacB.

METHODS

Recombinant hepatitis B surface and core antigen (HBsAg and HBcAg) particles were formulated with different liposome- or oil-in-water emulsion-based combination adjuvants containing saponin QS21 and monophosphoryl lipid A; these formulations were compared to STING-agonist c-di-AMP and conventional aluminium hydroxide formulations. Immunogenicity and the antiviral effects of protein antigen formulations and the MVA-vector boost within TherVacB were evaluated in adeno-associated virus-HBV-infected and HBV-transgenic mice.

RESULTS

Combination adjuvant formulations preserved HBsAg and HBcAg integrity for ≥12 weeks, promoted human and mouse dendritic cell activation and, within TherVacB, elicited robust HBV-specific antibody and T-cell responses in wild-type and HBV-carrier mice. Combination adjuvants that prime a balanced HBV-specific type 1 and 2 T helper response induced high-titer anti-HBs antibodies, cytotoxic T-cell responses and long-term control of HBV. In the absence of an MVA-vector boost or following selective CD8 T-cell depletion, HBsAg still declined (mediated mainly by anti-HBs antibodies) but HBV replication was not controlled. Selective CD4 T-cell depletion during the priming phase of TherVacB resulted in a complete loss of vaccine-induced immune responses and its therapeutic antiviral effect in mice.

CONCLUSIONS

Our results identify CD4 T-cell activation during the priming phase of TherVacB as a key determinant of HBV-specific antibody and CD8 T-cell responses.

IMPACT AND IMPLICATIONS

Therapeutic vaccination is a potentially curative treatment option for chronic hepatitis B. However, it remains unclear which factors are essential for breaking immune tolerance in HBV carriers and determining successful outcomes. Our study provides the first direct evidence that efficient priming of HBV-specific CD4 T cells determines the success of therapeutic hepatitis B vaccination in two preclinical HBV-carrier mouse models. Applying an optimal formulation of HBV antigens that activates CD4 and CD8 T cells during prime immunization provided the foundation for an antiviral effect of therapeutic vaccination, while depletion of CD4 T cells led to a complete loss of vaccine-induced antiviral efficacy. Boosting CD8 T cells was important to finally control HBV in these mouse models. Our findings provide important insights into the rational design of therapeutic vaccines for the cure of chronic hepatitis B.

Exosomes loading Tapasin enhance T cell immune response by autophagy to inhibit HBV replication

Hepatitis B virus (HBV) specific T cell immune response plays a vital role in viral clearance. Dendritic cell derived exosomes (Dexs) can activate T cell immunity effectively. Tapasin (TPN) is involved in antigen processing and specific immune recognition. In the present study, we elucidated that Dexs loading TPN (TPN-Dexs) could enhance CD8⁺ T cell immune response and inhibit virus replication in HBV transgenic mice. T cell immune response and the ability of inhibiting HBV replication were measured in HBV transgenic mice immunized with TPN-Dexs. Meanwhile, CD8⁺ T cell autophagy and specific T cell immune responses were measured in vitro and vivo, and the mechanisms probably involved in were explored. Purified TPN-Dexs could be taken up into the cytoplasm of DCs and upregulate CD8⁺ T cell autophagy to enhance specific T cell immune response. In addition, TPN-Dexs could increase the expression of AKT and decrease the expression of mTOR in CD8⁺ T cells. Further research confirmed that TPN-Dexs could inhibit virus replication and decrease the expression of HBsAg in the liver of HBV transgenic mice. Nevertheless, those also could elicit mice hepatocytes damage. In conclusion, TPN-Dexs could enhance specific CD8⁺ T cell immune responses via the AKT/mTOR pathway to regulate the autophagy and exert the antiviral effect in HBV transgenic mice.

JNK/c-Jun pathway activation is essential for HBx-induced IL-35 elevation to promote persistent HBV infection

BACKGROUND

Immunoregulation plays pivotal roles during chronic hepatitis B virus (HBV) infection. Studies have shown that Interleukin (IL)-35 is an important molecule associated with inadequate immune response against HBV. However, the mechanisms involved in the up-regulation of IL-35 expression during persistent HBV infection remain unknown.

METHODS

In this study, we constructed a plasmid expressing the HBV X protein (pCMV-HBx) to evaluate the relationship between HBx and IL-35. Activation of the JNK/c-Jun pathway was analyzed and chromatin immunoprecipitation followed by sequencing and luciferase reporter assays were performed to determine whether c-Jun could regulate IL-35 transcription.

RESULTS

HBx can significantly activate IL-35 promoter in both LO2 and HepG2 cells compared to the control plasmid (pCMV-Tag2) using the dual-luciferase assay. Whereas other viral proteins, such as S, preS1, the core protein, had no significant effect on IL-35 expression. Similarly, WB and qRT-PCR also showed that HBx can significantly promote IL-35 expression at protein and mRNA levels in the aforementioned cells. The relevant pathway mechanism showed that the expression of JNK and c-Jun genes was significantly higher in transfected cells carrying pCMV-HBx than in the pCMV-Tag2-transfected and -untransfected cells. WB analysis revealed that phosphorylated JNK and c-Jun were overexpressed after HBx action. Conversely, the addition of the JNK/c-Jun signaling pathway inhibitor could significantly suppress HBx-induced IL-35 expression in a dose-dependent manner.

CONCLUSIONS

A novel molecular mechanism of HBV-induced IL-35 expression was revealed, which involves JNK/c-Jun signaling in up-regulating IL-35 expression via HBx, resulting in transactivation of the IL-35 subunit EBI3 and p35 promoter.

Overview of the development of HBV small molecule inhibitors

Like tuberculosis and Acquired Immune Deficiency Syndrome (AIDS), hepatitis B is a globally recognized major public health threat. Although there are many small-molecule drugs for the treatment of hepatitis B, the approved drugs cannot eradicate the pathogenic culprit covalently closed circular DNA in patients, so the patients need long-term medication to control HBV amplification. Driven by a high unmet medical need, many pharmaceutical companies and research institutions have been engaged in the development of anti-HBV drugs to achieve a functional cure for chronic hepatitis B as soon as possible. This review summarizes the pathogenesis of hepatitis B virus and the research progress in the development of anti-HBV small molecule drugs, and introduces the cccDNA formation and transcription inhibitors and core inhibitors in detail, especially emphasizes the role of chinese herbal medicine in the treatment of chronic hepatitis B. Furthermore, this review proposes three potential strategies for cccDNA eradication in the future. We believe this review will provide meaningful guidance to achieve a functional cure for viral hepatitis B in the future.

Global dynamics of multiple delays within-host model for a hepatitis B virus infection of hepatocytes with immune response and drug therapy

In this paper, a mathematical model describing the hepatitis B virus (HBV) infection of hepatocytes with the intracellular HBV-DNA containing capsids, cytotoxic T-lymphocyte (CTL), antibodies including drug therapy (blocking new infection and inhibiting viral production) with two-time delays is studied. It incorporates the delay in the productively infected hepatocytes and the delay in an antigenic stimulation generating CTL. We verify the positivity and boundedness of solutions and determine the basic reproduction number. The local and global stability of three equilibrium points (infection-free, immune-free, and immune-activated) are investigated. Finally, the numerical simulations are established to show the role of these therapies in reducing viral replication and HBV infection. Our results show that the treatment by blocking new infection gives more significant results than the treatment by inhibiting viral production for infected hepatocytes. Further, both delays affect the number of infections and duration i.e. the longer the delay, the more severe the HBV infection.

Evaluation of the Effect of CD70 Co-Expression on CD8 T Cell Response in Protein-Prime MVA-Boost Vaccination in Mice

Here, we investigate the potential of CD70 co-expression during viral vector boost vaccination to improve an antigen-specific T cell response. To determine the chance of activating antigen-specific T cells by CD70, we used the HBV core antigen as a model antigen in a heterologous protein-prime, Modified Vaccinia virus Ankara (MVA) boost vaccination scheme. Both the HBV core and a CD70 expression cassette were co-expressed upon delivery by an MVA vector under the same promoter linked by a P2A site. To compare immunogenicity with and without CD70 co-expression, HBV-naïve, C57BL/6 (wt) mice and HBV-transgenic mice were prime-vaccinated using recombinant HBV core antigen followed by the MVA vector boost. Co-expression of CD70 increased the number of vaccine-induced HBV core-specific CD8 T cells by >2-fold and improved their effector functions in HBV-naïve mice. In vaccinated HBV1.3tg mice, the number and functionality of HBV core-specific CD8 T cells was slightly increased upon CD70 co-expression in low-viremic, but not in high-viremic animals. CD70 co-expression did not impact liver damage as indicated by ALT levels in the serum, but increased the number of vaccine-induced, proliferative T cell clusters in the liver. Overall, this study indicates that orchestrated co-expression of CD70 and a vaccine antigen may be an interesting and safe means of enhancing antigen-specific CD8 T cell responses using vector-based vaccines, although in our study it was not sufficient to break immune tolerance.

PreHevbrio: the first approved 3-antigen hepatitis B vaccine

INTRODUCTION

Hepatitis B remains a major cause of death and morbidity worldwide. Universal childhood immunization programs have been very successful, but many adults remain unprotected or are not optimally protected. PreHevbrio [Hepatitis B Vaccine (recombinant)] is a highly immunogenic 3-antigen (S/pre-S1/pre-S2) hepatitis B vaccine (3A-HBV) that recently received marketing authorization in the United States (2021), the European Union, United Kingdom (2022 - brand name PreHevbri), and Canada (2022- brand name PreHevbrio) for the prevention of infection caused by all known subtypes of the hepatitis B virus and the delta virus in adults 18 years and older.

AREAS COVERED

This review details the development of 3A-HBV and summarizes the results of the phase 3 clinical trials that support its immunogenicity and safety in adults.

EXPERT OPINION

3A-HBV is highly immunogenic in adults of all ages, including older adults and subgroups that respond sub-optimally to conventional single S-antigen hepatitis B vaccines (1A-HBV), such as those with obesity, type 2 diabetes, and smokers. 3A-HBV provides higher seroprotection rates after each vaccination compared to conventional 1A-HBV vaccines, allowing for more rapid protection. The higher overall immunogenicity is also reflected in more durable seroprotection years after vaccination, as supported by a follow-up study to one of the phase 3 studies.

Activation of distinct antiviral T-cell immunity: A comparison of bi- and trispecific T-cell engager antibodies with a chimeric antigen receptor targeting HBV envelope proteins

Despite the availability of an effective prophylactic vaccine, 820,000 people die annually of hepatitis B virus (HBV)-related liver disease according to WHO. Since current antiviral therapies do not provide a curative treatment for the 296 million HBV carriers around the globe, novel strategies to cure HBV are urgently needed. A promising approach is the redirection of T cells towards HBV-infected hepatocytes employing chimeric antigen receptors or T-cell engager antibodies. We recently described the effective redirection of T cells employing a second-generation chimeric antigen receptor directed against the envelope protein of hepatitis B virus on the surface of infected cells (S-CAR) as well as bispecific antibodies that engage CD3 or CD28 on T cells employing the identical HBV envelope protein (HBVenv) binder. In this study, we added a trispecific antibody comprising all three moieties to the tool-box. Cytotoxic and non-cytolytic antiviral activities of these bi- and trispecific T-cell engager antibodies were assessed in co-cultures of human PBMC with HBV-positive hepatoma cells, and compared to that of S-CAR-grafted T cells. Activation of T cells via the S-CAR or by either a combination of the CD3- and CD28-targeting bispecific antibodies or the trispecific antibody allowed for specific elimination of HBV-positive target cells. While S-CAR-grafted effector T cells displayed faster killing kinetics, combinatory treatment with the bispecific antibodies or single treatment with the trispecific antibody was associated with a more pronounced cytokine release. Clearance of viral antigens and elimination of the HBV persistence form, the covalently closed circular (ccc) DNA, through cytolytic as well as cytokine-mediated activity was observed in all three settings with the combination of bispecific antibodies showing the strongest non-cytolytic, cytokine-mediated antiviral effect. Taken together, we demonstrate that bi- and trispecific T-cell engager antibodies can serve as a potent, off-the-shelf alternative to S-CAR-grafted T cells to cure HBV.

Protective Effect of Neonatal Hepatitis B Vaccine Against HBV Breakthrough Infection in Children with Leukemia: A Real-world Study

BACKGROUND AND AIMS

Hepatitis B vaccine is the most effective preventive measure against hepatitis B virus (HBV) infection. However, the risk of HBV breakthrough infection in fully immunized children (neonatal hepatitis B immunization) who receive immunosuppressive therapy and transfusion of blood components is not well characterized. In this real-world study, we aimed to investigate the immune protection conferred by neonatal hepatitis B vaccine in children with acute lymphoblastic leukemia (ALL) who were treated with immunosuppressive therapy and blood component transfusions.

METHODS

Children with ALL who had received all three doses of neonatal hepatitis B vaccine were included in this study. HBV seromarkers were detected before and after the initiation of immunosuppressive therapy.

RESULTS

A total of 1,011 children with ALL who were fully vaccinated against hepatitis B in infancy before the initiation of immunosuppressive therapy were eligible for inclusion. HBV infection was detected in four of 410 children (0.98%) with an HBsAg test after the initiation of immunosuppressive therapy. The median interval from treatment initiation was 19 months.

CONCLUSIONS

Three doses of neonatal hepatitis B vaccine conferred adequate protection. In endemic regions, there is a low risk of HBV breakthrough infection in fully immunized children with immunosuppressive therapy.

Programmed Cell Death Protein 1 Axis Inhibition in Viral Infections: Clinical Data and Therapeutic Opportunities

A vital function of the immune system is the modulation of an evolving immune response. It is responsible for guarding against a wide variety of pathogens as well as the establishment of memory responses to some future hostile encounters. Simultaneously, it maintains self-tolerance and minimizes collateral tissue damage at sites of inflammation. In recent years, the regulation of T-cell responses to foreign or self-protein antigens and maintenance of balance between T-cell subsets have been linked to a distinct class of cell surface and extracellular components, the immune checkpoint molecules. The fact that both cancer and viral infections exploit similar, if not the same, immune checkpoint molecules to escape the host immune response highlights the need to study the impact of immune checkpoint blockade on viral infections. More importantly, the process through which immune checkpoint blockade completely changed the way we approach cancer could be the key to decipher the potential role of immunotherapy in the therapeutic algorithm of viral infections. This review focuses on the effect of programmed cell death protein 1/programmed death-ligand 1 blockade on the outcome of viral infections in cancer patients as well as the potential benefit from the incorporation of immune checkpoint inhibitors (ICIs) in treatment of viral infections.

Functional cure of a chronic virus infection by shifting the virus - host equilibrium state

The clinical handling of chronic virus infections remains a challenge. Here we describe recent progress in the understanding of virus - host interaction dynamics. Based on the systems biology concept of multi-stability and the prediction of multiplicative cooperativity between virus-specific cytotoxic T cells and neutralising antibodies, we argue for the requirements to engage multiple immune system components for functional cure strategies. Our arguments are derived from LCMV model system studies and are translated to HIV-1 infection.

HBeAg-Negative/Anti-HBe-Positive Chronic Hepatitis B: A 40-Year-Old History

Hepatitis B “e” antigen (HBeAg) negative chronic hepatitis B (CHB), 40 years since discovery in the Mediterranean area, has become the most prevalent form of HBV-induced liver disease worldwide and a major health care burden caused by HBV infection. A great deal of knowledge accumulated over the last decades provides consistent evidence on the bimodal dynamics of the expression of structural and non-structural forms of the viral core proteins which associate with different virologic and clinic–pathologic outcomes of HBV infection. In absence of serum HBeAg, the presence and persistence of HBV replication causes and maintains virus-related liver injury. Thus, in clinical practice it is mandatory to screen HBV carriers with HBeAg-negative infection for the early diagnosis of HBeAg-negative CHB since antiviral therapy can cure HBV-induced liver disease when started at early stages.

Intrahepatic transcriptomics reveals gene signatures in chronic hepatitis B patients responded to interferon therapy

Chronic hepatitis B virus (HBV) infection remains a substantial public health burden worldwide. Alpha-interferon (IFNα) is one of the two currently approved therapies for chronic hepatitis B (CHB), to explore the mechanisms underlying IFNα treatment response, we investigated baseline and 24-week on-treatment intrahepatic gene expression profiles in 21 CHB patients by mRNA-seq. The data analyses demonstrated that PegIFNα treatment significantly induced antiviral responses. Responders who achieved HBV DNA loss and HBeAg or HBsAg seroconversion displayed higher fold change and larger number of up-regulated interferon-stimulated genes (ISGs). Interestingly, lower expression levels of certain ISGs were observed in responders in their baseline biopsy samples. In HBeAg+ patients, non-responders had relative higher baseline HBeAg levels than responders. More importantly, HBeAg− patients showed higher HBsAg loss rate than HBeAg+ patients. Although a greater fold change of ISGs was observed in HBeAg− patients than HBeAg+ patients, upregulation of ISGs in HBeAg+ responders exceeded HBeAg− responders. Notably, PegIFNα treatment increased monocyte and mast cell infiltration, but decreased CD8 T cell and M1 macrophage infiltration in both responders and non-responders, while B cell infiltration was increased only in responders. Moreover, co-expression analysis identified ribosomal proteins as critical players in antiviral response. The data also indicate that IFNα may influence the production of viral antigens associated with endoplasmic reticulum. Collectively, the intrahepatic transcriptome analyses in this study enriched our understanding of IFN-mediated antiviral effects in CHB patients and provided novel insights into the development of potential strategies to improve IFNα therapy.

A Multicenter Real-World Study Evaluating the Hepatoprotective Effect of Polyene Phosphatidylcholine Against Chronic Hepatitis B

Background

Polyene phosphatidylcholine (PPC) has been widely used to treat liver diseases in China. However, there is a lack of post-marketing evidence demonstrating its liver-protective efficiency among patients infected with hepatitis B virus (HBV). This study analyzed the multicenter real-world data to compare the effectiveness of PPC with those of magnesium isoglycyrrhizinate (IsoMag) and glutathione (GSH) in patients with liver injury.

Methods

This study comprised the real-world data analysis of a multicenter, retrospective observational cohort. The data were retrieved from the Cooperative Registry of the Hospital Prescription in China between 1 October 2018, and 30 September 2019. A growth curve analysis was performed to compare the effects of different treatments on liver function longitudinally for up to 30 days after treatment commencement. In addition, the dose effect of the PPC treatment was investigated.

Results

The final cohort included 6,052 patients with approximately 8% infected with HBV (N = 471). There were 1,649, 1,750, and 2,653 patients in the PPC, GSH, and IsoMag groups, respectively, with an average age of 53.9 years. In patients with HBV infection, the PPC treatment was associated with a significant decline in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels (slopes: −3.7, 95% CI, −6.0 to −1.5 U/L/day; −2.4, 95% CI, −4.5 to −0.3 U/L/day, respectively). However, there were no significant differences in the effects among the three groups. In patients without HBV infection, the PPC treatment decreased ALT, AST, γ-glutamyl transferase (GGT), and albumin levels (−5.2, 95% CI, −5.8 to −4.5 U/L/day; −3.5, 95% CI, −4.2 to −2.7 U/L/day; −4.9, 95% CI, −6.2 to −3.7 U/L/day, −0.07, 95% CI, −0.09 to −0.04 g/L/day, respectively) and showed a stronger effect on lowering ALT levels than GSH (−2.6, 95% CI, −3.3 to −1.8 U/L/day, p < 0.05), as well as a stronger effect on lowering GGT levels than IsoMag (−1.4, 95% CI, −2.4 to −0.4 U/L/day, p < 0.05). PPC had no impact on prothrombin activity levels in patients with or without HBV infection. High-dose PPC exhibited a stronger effect on lowering ALT and AST levels than low-dose PPC.

Conclusion

This was the first real-world multicenter study to demonstrate that PPC efficiently lowers ALT and AST levels in patients with liver diseases regardless of the status of HBV infection. PPC treatment showed a comparable or better effect compared with GSH and IsoMag treatments. High-dose PPC resulted in a stronger effect than low-dose PPC.

The loss and return of self: An interpretative phenomenological analysis of coping and recovery from chronic hepatitis B in China

Chronic hepatitis B (CHB) is a prevalent disease with various negative consequences. The lived experience of coping and recovery of a patient with Chronic hepatitis B was explored in this study. A semistructured interview was conducted with one participant who had been recovered from Chronic hepatitis B for 10 years. Data were analyzed using interpretative phenomenological analysis. Five superordinate themes emerged, including lingering in the shadow of death anxiety, diminished functioning of the self, adopting a highly disciplined lifestyle, receiving social support, and the return of the self with scars. The findings revealed that the disease is deeply associated with moral standing, which means the diagnosis of Chronic hepatitis B might imply a loss of moral face for Chinese people living with the condition. Our findings point to the need for increasing knowledge about chronic hepatitis B, decoupling the disease from a moral standpoint, and providing a supportive environment.

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.

Antiviral cytotoxic T lymphocyte responses for long term prognosis of corneal infection by cytomegalovirus in immunocompetent subjects

Ocular cytomegalovirus (CMV) infections in immunocompetent individuals are rare, but its activation can cause chronic and relapsing inflammation in anterior segment of the eye resulting in loss of corneal clarity and glaucoma. Fifty five patients with anterior segment CMV infection were assessed for their clinical characteristics, and CMV corneal endotheliitis was found to cause significant loss of corneal endothelial cells. The disease duration with recurrences was significantly correlated with the maximum intraocular level of CMV DNA. To examine why CMV is activated in healthy immunocompetent individuals and causing corneal endothelial cell damage, assays of cytotoxic T cells (CTLs) which directly target infected corneal endothelial cells were performed for 9 HLA-matched CMV corneal endotheliitis patients (HLA-A*2402). When the cell loss was analyzed for associations with CTL responses, CMV-induced endothelial cell damage was mitigated by pp65-specific CTL induction. The recurrence-free time was also prolonged by pp65-specific CTL induction (hazard ratio (HR): 0.93, P = 0.01). In contrast, IE1-specific CTL was associated with endothelial cell damage and reduced the time for corneal transplantation (HR: 1.6, P = 0.003) and glaucoma surgery (HR: 1.5, P = 0.001). Collectively, induction of pp65-specific CTL was associated with improved visual prognosis. However, IE1-specific CTL without proper induction of pp65-specific CTL can cause pathological damage leading to the need of surgical interventions.

Anti-rheumatic drug-induced hepatitis B virus reactivation and preventive strategies for hepatocellular carcinoma

To date, an estimated 3 million people worldwide have been infected with chronic hepatitis B virus (HBV). Although anti-HBV therapies have improved the long-term survival profile of chronic carriers, viral reactivation still poses a significant challenge for preventing HBV-related hepatitis, hepatocellular carcinoma (HCC), and death. Immuno-modulating drugs, which are widely applied in managing rheumatic conditions, are commonly associated with HBV reactivation (HBVr) as a result of drug-induced immune suppression. However, there are few reports on the risk of HBVr and the medication management plan for HBV carriers, especially rheumatic patients. In this review, we summarize immuno-modulating drug-induced HBVr during rheumatoid therapy and its preventive strategies for HBVr-induced liver diseases, especially cirrhosis and HCC. These findings will assist with developing treatments for rheumatic patients, and prevent HBV-related cirrhosis and HCC.

Pathogenicity and virulence of Hepatitis B virus

Hepatitis B virus (HBV) is a hepatotropic virus and an important human pathogen. There are an estimated 296 million people in the world that are chronically infected by this virus, and many of them will develop severe liver diseases including hepatitis, cirrhosis and hepatocellular carcinoma (HCC). HBV is a small DNA virus that replicates via the reverse transcription pathway. In this review, we summarize the molecular pathways that govern the replication of HBV and its interactions with host cells. We also discuss viral and non-viral factors that are associated with HBV-induced carcinogenesis and pathogenesis, as well as the role of host immune responses in HBV persistence and liver pathogenesis.

The association between Fc gamma RIIb expression levels and chronic hepatitis B virus infection progression

BACKGROUND

Fc gamma receptor IIb (FcγRIIb) is an important inhibitory receptor that plays vital roles in regulating various immune response processes and the pathogenesis of many infectious diseases. The purpose of our research was to evaluate FcγRIIb expression in serum and liver biopsy specimens from hepatitis B virus (HBV)-infected patients and to explore the association of FcγRIIb with chronic HBV infection.

METHODS

Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the serum FcγRIIb levels in 119 HBV-infected patients and 24 healthy controls. An immunohistochemical method was then employed to identify FcγRIIb expression in biopsy specimens from patients with chronic hepatitis B (CHB). The integrated optical density (IOD) value was measured to represent FcγRIIb expression levels.

RESULTS

Serum FcγRIIb levels were decreased in CHB patients compared to controls (P < 0.001). The FcγRIIb levels in the CHB patient group were remarkably lower than those in the HBV carrier group (P < 0.001). In addition, FcγRIIb levels were negatively associated with AST and ALT (r = -0.3936, P = 0.0063; r = -0.3459, P = 0.0097, respectively). The IOD values of FcγRIIb expression in the moderate and severe CHB groups were significantly lower than those in the control group (P = 0.006 and P < 0.001, respectively). The FcγRIIb level tended to be lower with pathological changes related to hepatitis. Furthermore, correlation analysis revealed that FcγRIIb had negative correlations with AST and ALT (r = -0.688, P = 0.0016; r = -0.686, P = 0.0017, respectively) but a positive association with the platelet count (r = 0.6464, P = 0.0038).

CONCLUSIONS

FcγRIIb levels are significantly related to chronic HBV infection and the progression of CHB. Changes in FcγRIIb may affect the progression of liver inflammation and fibrosis in CHB patients.

In Vivo Bioluminescence Imaging of HBV Replicating Hepatocytes Allows for the Monitoring of Anti-Viral Immunity

Immunity against hepatitis B virus (HBV) infection is complex and not entirely understood so far, including the decisive factors leading to the development of chronic hepatitis B. This lack of a mechanistic understanding of HBV-specific immunity is also caused by a limited number of suitable animal models. Here, we describe the generation of a recombinant adenovirus expressing an HBV 1.3-overlength genome linked to luciferase (Ad-HBV-Luc) allowing for precise analysis of the quantity of infected hepatocytes. This enables sensitive and close-meshed monitoring of HBV-specific CD8 T cells and the onset of anti-viral immunity in mice. A high dose of Ad-HBV-Luc developed into chronic hepatitis B accompanied by dysfunctional CD8 T cells characterized by high expression of PD1 and TOX and low expression of KLRG1 and GzmB. In contrast, a low dose of Ad-HBV-Luc infection resulted in acute hepatitis with CD8 T cell-mediated elimination of HBV-replicating hepatocytes associated with elevated sALT levels and increased numbers of cytotoxic HBV-specific CD8 T cells. Thus, the infectious dose was a critical factor to induce either acute self-limited or chronic HBV infection in mice. Taken together, the new Ad-HBV-Luc vector will allow for highly sensitive and time-resolved analysis of HBV-specific immune responses during acute and chronic infection.

Cytokines profile in patients with acute and chronic hepatitis B infection

Hepatitis B virus (HBV) is one of the leading causes of acute and chronic hepatitis and represents a serious public health threat. Cytokines are important chemical mediators that regulate the differentiation, proliferation, and function of immune cells, with accumulating evidence indicating that the inadequate immune responses are responsible for the elimination or persistence of HBV. This study aimed to determine the cytokine profiles (IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10, and IL-17A) during HBV infection and investigate their association with genotypes. A total of 66 plasma samples, 19 from patients with acute and 47 with chronic hepatitis B infection, were subjected to biochemical tests, nested-PCR, and real-time PCR, with cytokines evaluated using a commercial BD Cytometric Bead Array Human Th1/Th2/Th17 Cytokine Kit. Healthy controls (10 individuals) were selected from blood donors with no history of liver diseases. No correlation was found between genotypes, viral load, and cytokines analyzed. All cytokines showed higher levels of production among infected individuals when compared with the control group. A positive correlation classified as moderate to strong was found between cytokines IFN-γ, TNF, IL-10, IL-6, IL-4, and IL-2 through the Spearman correlation coefficient. TNF (P = 0.009), IL-10 (P < 0.001), and IL-6 (P < 0.001) levels were higher in acute individuals compared with chronic and control groups. Theses cytokines could be involved in the elimination of virus and protection against chronicity.

Exploring evidence-based innovative therapy for the treatment of chronic HBV infection: experimental and clinical

With the advent of various vaccines and antimicrobial agents during the 20th century, the control and containment of infectious diseases appeared to be a matter of time. However, studies unveiled the diverse natures of microbes, their lifestyle, and pathogenetic potentials. Since the ground-breaking discovery of the hepatitis B virus (HBV) by Baruch Blumberg and the subsequent development of a vaccine in the early 1980s, the main task of the scientific community has been to develop a proper management strategy for HBV-induced chronic liver diseases. In the early 1980’s, standard interferon (IFN) induced a reduction of HBV DNA levels, followed by the normalization of serum transaminases (alanine aminotransferase, ALT), in some chronic hepatitis B (CHB) patients. However, in the course of time, the limitations of standard IFN became evident, and the search for an alternative began. In the late 1980’s, nucleoside analogs entered the arena of CHB treatment as oral drugs with potent antiviral capacities. At the beginning of the 21st century, insights were developed into the scope and limitations of standard IFN, pegylated-IFN as well as nucleoside analogs for treating CHB. Considering the non-cytopathic nature of the HBV, the presence of covalently closed circular DNA (cccDNA) in the nucleus of the infected hepatocytes and HBV-induced immune-mediated liver damages, a new field of CHB management was initiated by modulating the hosts’ immune system through immune therapy. This review will discuss the nature and design of innovative immune therapy for CHB.

Hepatitis B Vaccine Non-Responders Show Higher Frequencies of CD24highCD38high Regulatory B Cells and Lower Levels of IL-10 Expression Compared to Responders

Background

The cellular mechanisms involved in the lack of protective antibody response after hepatitis B vaccination are still rather unclear. Regulatory B cells (Breg) known as modulators of B-and T-cell responses may contribute to poor vaccine responsiveness. The current study aimed to investigate the role of regulatory B cells (Breg) in hepatitis B vaccine non-responsiveness after immunization with second- or third-generation hepatitis B vaccines.

Method

We performed comparative phenotypic and frequency analysis of Breg subsets (CD24⁺CD27⁺ and CD24^highCD38^high Breg) in second-generation hepatitis B vaccine non-responders (2^nd HBvac NR, n = 11) and responders (2^nd HBvac R, n = 8) before (d0), on day 7 (d7), and 28 (d28) after booster vaccination. Cryopreserved peripheral blood mononuclear cells were stimulated ex vivo with a combination of CpG, PMA, and Ionomycin (CpG+P/I) and analyzed for numbers and IL-10 expression levels of Breg by flow cytometry-based analyses.

Results

Flow cytometry-based analyses revealed elevated frequencies of CD24⁺CD27⁺ Breg at all time points and significantly higher frequencies of CD24^highCD38^high Breg on d0 (p = 0.004) and 28 (p = 0.012) in 2^nd HBvac NR compared to 2^nd HBvac R. In parallel, we observed significantly lower levels of CpG+P/I-induced IL-10 expression levels of CD24⁺CD27⁺ and CD24^highCD38^high Breg (d0: p < 0.0001; d7: p = 0.0004; d28: p = 0.0003 and d0: p = 0.016; d7: p = 0.016, respectively) in 2^nd HBvac NR compared to 2^nd HBvac R before and after booster immunization. Frequencies of CD24⁺CD27⁺ and CD24^highCD38^high Breg significantly decreased after third-generation hepatitis B booster vaccination (d7: p = 0.014; d28: p = 0.032 and d7: p = 0.045, respectively), whereas IL-10 expression levels of both Breg subsets remained stable.

Conclusion

Here we report significantly higher frequencies of CD24^highCD38^high Breg in parallel with significantly lower IL-10 expression levels of CD24⁺CD27⁺ and CD24^highCD38^high Breg in 2^nd HBvac NR compared to 2^nd HBvac R. Anti-HBs seroconversion accompanied by a decrease of Breg numbers after booster immunization with a third-generation hepatitis B vaccine could indicate a positive effect of third-generation hepatitis B vaccines on Breg-mediated immunomodulation in hepatitis B vaccine non-responders.

Detection of the serological markers hepatitis B virus surface antigen (HBsAg) and hepatitis B core IgM antibody (anti-HBcIgM) in the diagnosis of acute hepatitis B virus infection after recent exposure

The serological diagnosis of acute hepatitis B virus (HBV) infection after recent exposure has been established by the hepatitis B virus surface antigen (HBsAg) and anti-hepatitis B core IgM antibody (anti-HBcIgM) detection in serum, sometimes accompanied by the detection of hepatitis B "e" antigen (HBeAg). Despite this characteristic serological profile, misdiagnosis can occur in cases of unexpected or atypical behavior of the serological markers in the bloodstream, or if the true meaning of its expression is not properly investigated, or even if there is a possibility of interference from factors not necessarily linked to the infectious process, in the detection of these markers. This review discusses the influence of these variables on laboratory results for these two serological markers and, therefore, the potential risk of these variables compromising the correct diagnosis of acute infection after recent HBV exposure.

Research status and progress of drug induced liver injury

The incidence rate of drug-induced liver injury has been high with the extensive use of drugs and the development and application of new drugs. The pathogenesis of drug-induced liver injury is not fully understood, so there is no significant breakthrough in its treatment. The diagnosis of drug-induced liver injury still depends on drug history, clinical manifestations, imaging, biochemical tests, and liver biopsy. This article reviews the recent progress in the understanding of the incidence rate, classification, risk factors, and serum markers of drug-induced liver injury.

HBV-Specific CD8+ T-Cell Tolerance in the Liver

Hepatitis B virus (HBV) remains a leading cause of liver-related morbidity and mortality through chronic hepatitis that may progress to liver cirrhosis and cancer. The central role played by HBV-specific CD8+ T cells in the clearance of acute HBV infection, and HBV-related liver injury is now well established. Vigorous, multifunctional CD8+ T cell responses are usually induced in most adult-onset HBV infections, while chronic hepatitis B (CHB) is characterized by quantitatively and qualitatively weak HBV-specific CD8+ T cell responses. The molecular basis of this dichotomy is poorly understood. Genomic analysis of dysfunctional HBV-specific CD8+ T cells in CHB patients and various mouse models suggest that multifaceted mechanisms including negative signaling and metabolic abnormalities cooperatively establish CD8+ T cell dysfunction. Immunoregulatory cell populations in the liver, including liver resident dendritic cells (DCs), hepatic stellate cells (HSCs), myeloid-derived suppressor cells (MDSCs), may contribute to intrahepatic CD8+ T cell dysfunction through the production of soluble mediators, such as arginase, indoleamine 2,3-dioxygenase (IDO) and suppressive cytokines and the expression of co-inhibitory molecules. A series of recent studies with mouse models of HBV infection suggest that genetic and epigenetic changes in dysfunctional CD8+ T cells are the manifestation of prolonged antigenic stimulation, as well as the absence of co-stimulatory or cytokine signaling. These new findings may provide potential new targets for immunotherapy aiming at invigorating HBV-specific CD8+ T cells, which hopefully cures CHB.

Molecular Mechanisms during Hepatitis B Infection and the Effects of the Virus Variability

The immunopathogenesis and molecular mechanisms involved during a hepatitis B virus (HBV) infection have made the approaches for research complex, especially concerning the patients’ responses in the course of the early acute stage. The study of molecular bases involved in the viral clearance or persistence of the infection is complicated due to the difficulty to detect patients at the most adequate points of the disease, especially in the time lapse between the onset of the infection and the viral emergence. Despite this, there is valuable data obtained from animal and in vitro models, which have helped to clarify some aspects of the early immune response against HBV infection. The diversity of the HBV (genotypes and variants) has been proven to be associated not only with the development and outcome of the disease but also with the response to treatments. That is why factors involved in the virus evolution need to be considered while studying hepatitis B infection. This review brings together some of the published data to try to explain the immunological and molecular mechanisms involved in the different stages of the infection, clinical outcomes, viral persistence, and the impact of the variants of HBV in these processes.