Cellular immune responses to the hepatitis B virus polymerase

The role of regulatory T cells and follicular T helper cells in HBV infection

Hepatitis B has become one of the major global health threats, especially in developing countries and regions. Hepatitis B virus infection greatly increases the risk for liver diseases such as cirrhosis and cancer. However, treatment for hepatitis B is limited when considering the huge base of infected people. The immune response against hepatitis B is mediated mainly by CD8+ T cells, which are key to fighting invading viruses, while regulatory T cells prevent overreaction of the immune response process. Additionally, follicular T helper cells play a key role in B-cell activation, proliferation, differentiation, and formation of germinal centers. The pathogenic process of hepatitis B virus is generally the result of a disorder or dysfunction of the immune system. Therefore, we present in this review the critical functions and related biological processes of regulatory T cells and follicular T helper cells during HBV infection.

Hepatitis B virus-specific CD4 T cell responses differentiate functional cure from chronic surface antigen+ infection

BACKGROUND & AIMS

With or without antiviral treatment, few individuals achieve sustained functional cure of chronic hepatitis B virus (HBV) infection. A better definition of what mediates functional cure is essential for improving immunotherapeutic strategies. We aimed to compare HBV-specific T cell responses in patients with different degrees of viral control.

METHODS

We obtained blood from 124 HBV-infected individuals, including those with acute self-limiting HBV infection, chronic infection, and chronic infection with functional cure. We screened for HBV-specific T cell specificities by ELISpot, assessed the function of HBV-specific T cells using intracellular cytokine staining, and characterized HBV-specific CD4 T cells using human leukocyte antigen (HLA) class II tetramer staining, all directly ex vivo.

RESULTS

ELISpot screening readily identified HBV-specific CD4 and CD8 T cell responses in acute resolving infection compared with more limited reactivity in chronic infection. Applying more sensitive assays revealed higher frequencies of functional HBV-specific CD4 T cells, but not CD8 T cells, in functional cure compared to chronic infection. Function independent analysis using HLA multimers also identified more HBV-specific CD4 T cell responses in functional cure compared to chronic infection, with the emergence of CD4 T cell memory both after acute and chronic infection.

CONCLUSIONS

Functional cure is associated with higher frequencies of functional HBV-specific CD4 memory T cell responses. Thus, immunotherapeutic approaches designed to induce HBV functional cure should also aim to improve CD4 T cell responses.

LAY SUMMARY

Immunotherapy is a form of treatment that relies on harnessing the power of an individual's immune system to target a specific disease or pathogen. Such approaches are being developed for patients with chronic HBV infection, in an attempt to mimic the immune response in patients who control HBV infection spontaneously, achieving a so-called functional cure. However, what exactly defines protective immune responses remains unclear. Herein, we show that functional cure is associated with robust responses by HBV-specific CD4 T cells (a type of immune cell).

Spacer Domain in Hepatitis B Virus Polymerase: Plugging a Hole or Performing a Role?

Hepatitis B virus (HBV) polymerase is divided into terminal protein, spacer, reverse transcriptase, and RNase domains. Spacer has previously been considered dispensable, merely acting as a tether between other domains or providing plasticity to accommodate deletions and mutations. We explore evidence for the role of spacer sequence, structure, and function in HBV evolution and lineage, consider its associations with escape from drugs, vaccines, and immune responses, and review its potential impacts on disease outcomes.

Screening and Identification of HBV Epitopes Restricted by Multiple Prevalent HLA-A Allotypes

Although host T cell immune responses to hepatitis B virus (HBV) have been demonstrated to have important influences on the outcome of HBV infection, the development of T cell epitope-based vaccine and T cell therapy and the clinical evaluation of specific T cell function are currently hampered markedly by the lack of validated HBV T cell epitopes covering broad patients. This study aimed to screen T cell epitopes spanning overall HBsAg, HBeAg, HBx and HBpol proteins and presenting by thirteen prevalent human leukocyte antigen (HLA)-A allotypes which gather a total gene frequency of around 95% in China and Northeast Asia populations. 187 epitopes were in silico predicted. Of which, 62 epitopes were then functionally validated as real-world HBV T cell epitopes by ex vivo IFN-γ ELISPOT assay and in vitro co-cultures using peripheral blood mononuclear cells (PBMCs) from HBV infected patients. Furthermore, the HLA-A cross-restrictions of each epitope were identified by peptide competitive binding assay using transfected HMy2.CIR cell lines, and by HLA-A/peptide docking as well as molecular dynamic simulation. Finally, a peptide library containing 105 validated epitopes which cross-binding by 13 prevalent HLA-A allotypes were used in ELISPOT assay to enumerate HBV-specific T cells for 116 patients with HBV infection. The spot forming units (SFUs) was significantly correlated with serum HBsAg level as confirmed by multivariate linear regression analysis. This study functionally validated 62 T cell epitopes from HBV main proteins and elucidated their HLA-A restrictions and provided an alternative ELISPOT assay using validated epitope peptides rather than conventional overlapping peptides for the clinical evaluation of HBV-specific T cell responses.

A Systematic Review of T Cell Epitopes Defined from the Proteome of Hepatitis B Virus

Hepatitis B virus (HBV) infection remains a worldwide health problem and no eradicative therapy is currently available. Host T cell immune responses have crucial influences on the outcome of HBV infection, however the development of therapeutic vaccines, T cell therapies and the clinical evaluation of HBV-specific T cell responses are hampered markedly by the lack of validated T cell epitopes. This review presented a map of T cell epitopes functionally validated from HBV antigens during the past 33 years; the human leukocyte antigen (HLA) supertypes to present these epitopes, and the methods to screen and identify T cell epitopes. To the best of our knowledge, a total of 205 CD8⁺ T cell epitopes and 79 CD4⁺ T cell epitopes have been defined from HBV antigens by cellular functional experiments thus far, but most are restricted to several common HLA supertypes, such as HLA-A0201, A2402, B0702, DR04, and DR12 molecules. Therefore, the currently defined T cell epitope repertoire cannot cover the major populations with HLA diversity in an indicated geographic region. More researches are needed to dissect a more comprehensive map of T cell epitopes, which covers overall HBV proteome and global patients.

CD4+ T Cells in Chronic Hepatitis B and T Cell-Directed Immunotherapy

The impaired T cell responses observed in chronic hepatitis B (HBV) patients are considered to contribute to the chronicity of the infection. Research on this impairment has been focused on CD8⁺ T cells because of their cytotoxic effector function; however, CD4⁺ T cells are crucial in the proper development of these long-lasting effector CD8⁺ T cells. In this review, we summarize what is known about CD4⁺ T cells in chronic HBV infection and discuss the importance and opportunities of including CD4⁺ T cells in T cell-directed immunotherapeutic strategies to cure chronic HBV.

Designing the next-generation therapeutic vaccines to cure chronic hepatitis B: focus on antigen presentation, vaccine properties and effect measures

In the mid‐90s, hepatitis B virus (HBV)‐directed immune responses were for the first time investigated in detail and revealed suboptimal T‐cell responses in chronic HBV patients. Based on these studies, therapeutic vaccination exploiting the antigen presentation capacity of dendritic cells to prime and/or boost HBV‐specific T‐cell responses was considered highly promising. Now, 25 years later, it has not yet delivered this promise. In this review, we summarise what has been clinically tested in terms of antigen targets and vaccine forms, how the immunological and therapeutic effects of these vaccines were assessed and what major clinical and immunological findings were reported. We combine the lessons learned from these trials with the most recent insights on HBV antigen presentation, T‐cell responses, vaccine composition, antiviral and immune‐modulatory drugs and disease biomarkers to derive novel opportunities for the next generation of therapeutic vaccines designed to cure chronic HBV either alone or in combination therapy.

Single-Domain Antibody-Based TCR-Like CAR-T: A Potential Cancer Therapy

Retargeting the antigen-binding specificity of T cells to intracellular antigens that are degraded and presented on the tumor surface by engineering chimeric antigen receptor (CAR), also named TCR-like antibody CAR-T, remains limited. With the exception of the commercialized CD19 CAR-T for hematological malignancies and other CAR-T therapies aiming mostly at extracellular antigens achieving great success, the rareness and scarcity of TCR-like CAR-T therapies might be due to their current status and limitations. This review provides the probable optimized initiatives for improving TCR-like CAR-T reprogramming and discusses single-domain antibodies administered as an alternative to conventional scFvs and secreted by CAR-T cells, which might be of great value to the development of CAR-T immunotherapies for intracellular antigens.

HBVsvp-Pulsed Dendritic Cell Immunotherapy Induces Th1 Polarization and Hepatitis B Virus-Specific Cytotoxic T Lymphocytes Production

Background

In chronic hepatitis B virus (CHB) patients, both dendritic cells (DCs) and T cells are functionally impaired and consequently the HBV-specific cellular immune responses are downregulated. The present study aims to investigate whether monocyte-derived DC (MoDCs)-pulsed-HBV subviral particles (HBVsvp) can polarize Th1 cells to induce HBV-specific cytotoxic T-lymphocytes (CTL) responses in CHB patients.

Methods and Materials

To this end, the human hepatoma HepG2.2.15 cell line was used to produce HBVsvp as a culturing system, and HBVsvp were concentrated for highly virus titer using the polyethylene glycol protocol. Peripheral blood mononuclear cells (PBMCs), collected from CHB patients and healthy donors, were differentiated into MoDCs and T cells. PBMCs-derived MoDCs were first pulsed with HBVsvp and then cultured with PBMCs-derived T cells. MoDCs and/or T subsets cells were identified for phenotypic activation by FACS analysis. The cytokine secretion of IL-4, IL-12, and IFN-γ in the culture supernatants was detected.

Results

The MoDCs were restored for their activation upon pulsing with HBVsvp in vitro, as identified by significantly overexpression of both CD86 and HLA-DR, and overproduction of IL-4 and IL-12. Furthermore, MoDCs-pulsed-HBVsvp induced Th1 frequencies and activated HBV-specific CTL to produce significantly highest amount of IFN-γ. Enhanced HBV-specific CTL led to strong cytolytic capacity against HepG2.2.15.

Conclusion

Overall, our data suggest that in vitro activation of MoDCs with HBVsvp overcomes the functionally impaired DCs and T cells in CHB patients offering a promising tool for therapeutic or vaccine-based approaches against HBV.

In Silico Prediction of Human Leukocytes Antigen (HLA) Class II Binding Hepatitis B Virus (HBV) Peptides in Botswana

Hepatitis B virus (HBV) is the primary cause of liver-related malignancies worldwide, and there is no effective cure for chronic HBV infection (CHB) currently. Strong immunological responses induced by T cells are associated with HBV clearance during acute infection; however, the repertoire of epitopes (epi) presented by major histocompatibility complexes (MHCs) to elicit these responses in various African populations is not well understood. In silico approaches were used to map and investigate 15-mers HBV peptides restricted to 9 HLA class II alleles with high population coverage in Botswana. Sequences from 44 HBV genotype A and 48 genotype D surface genes (PreS/S) from Botswana were used. Of the 1819 epi bindings predicted, 20.2% were strong binders (SB), and none of the putative epi bind to all the 9 alleles suggesting that multi-epitope, genotype-based, population-based vaccines will be more effective against HBV infections as opposed to previously proposed broad potency epitope-vaccines which were assumed to work for all alleles. In total, there were 297 unique epi predicted from the 3 proteins and amongst, S regions had the highest number of epi (n = 186). Epitope-densities (Depi) between genotypes A and D were similar. A number of mutations that hindered HLA-peptide binding were observed. We also identified antigenic and genotype-specific peptides with characteristics that are well suited for the development of sensitive diagnostic kits. This study identified candidate peptides that can be used for developing multi-epitope vaccines and highly sensitive diagnostic kits against HBV infection in an African population. Our results suggest that viral variability may hinder HBV peptide-MHC binding, required to initiate a cascade of immunological responses against infection.

TNF-α/IFN-γ profile of HBV-specific CD4 T cells is associated with liver damage and viral clearance in chronic HBV infection

BACKGROUND & AIMS

The role of hepatitis B virus (HBV)-specific CD4 T cells in patients with chronic HBV infection is not clear. Thus, we aimed to elucidate this in patients with chronic infection, and those with hepatitis B flares.

METHODS

Through intracellular IFN-γ and TNF-α staining, HBV-specific CD4 T cells were analyzed in 68 patients with chronic HBV infection and alanine aminotransferase (ALT) <2x the upper limit of normal (ULN), and 28 patients with a hepatitis B flare. HBV-specific HLA-DRB1*0803/HLA-DRB1*1202-restricted CD4 T cell epitopes were identified.

RESULTS

TNF-α producing cells were the dominant population in patients' HBV-specific CD4 T cells. In patients with ALT <2xULN, both the frequency and the dominance of HBV-specific IFN-γ producing CD4 T cells increased sequentially in patients with elevated levels of viral clearance: HBV e antigen (HBeAg) positive, HBeAg negative, and HBV surface antigen (HBsAg) negative. In patients with a hepatitis B flare, the frequency of HBV core-specific TNF-α producing CD4 T cells was positively correlated with patients' ALT and total bilirubin levels, and the frequency of those cells changed in parallel with the severity of liver damage. Patients with HBeAg/HBsAg loss after flare showed higher frequency and dominance of HBV-specific IFN-γ producing CD4 T cells, compared to patients without HBeAg/HBsAg loss. Both the frequency and the dominance of HBV S-specific IFN-γ producing CD4 T cells were positively correlated with the decrease of HBsAg during flare. A differentiation process from TNF-α producing cells to IFN-γ producing cells in HBV-specific CD4 T cells was observed during flare. Eight and 9 HBV-derived peptides/pairs were identified as HLA-DRB1*0803 restricted epitopes and HLA-DRB1*1202 restricted epitopes, respectively.

CONCLUSIONS

HBV-specific TNF-α producing CD4 T cells are associated with liver damage, while HBV-specific IFN-γ producing CD4 T cells are associated with viral clearance in patients with chronic HBV infection.

LAY SUMMARY

TNF-α producing cells are the dominant population of hepatitis B virus (HBV)-specific CD4 T cells in patients with chronic HBV infection. This population of cells might contribute to the aggravation of liver damage in patients with a hepatitis B flare. HBV-specific IFN-γ producing CD4 T cells are associated with HBV viral clearance. Differentiation from HBV-specific TNF-α producing CD4 T cells into HBV-specific IFN-γ producing CD4 T cells might favor HBV viral clearance.

Targeting cancers through TCR-peptide/MHC interactions

Adoptive T cell therapy has achieved dramatic success in a clinic, and the Food and Drug Administration approved two chimeric antigen receptor-engineered T cell (CAR-T) therapies that target hematological cancers in 2018. A significant issue faced by CAR-T therapies is the lack of tumor-specific biomarkers on the surfaces of solid tumor cells, which hampers the application of CAR-T therapies to solid tumors. Intracellular tumor-related antigens can be presented as peptides in the major histocompatibility complex (MHC) on the cell surface, which interact with the T cell receptors (TCR) on antigen-specific T cells to stimulate an anti-tumor response. Multiple immunotherapy strategies have been developed to eradicate tumor cells through targeting the TCR-peptide/MHC interactions. Here, we summarize the current status of TCR-based immunotherapy strategies, with particular focus on the TCR structure, activated signaling pathways, the effects and toxicity associated with TCR-based therapies in clinical trials, preclinical studies examining immune-mobilizing monoclonal TCRs against cancer (ImmTACs), and TCR-fusion molecules. We propose several TCR-based therapeutic strategies to achieve optimal clinical responses without the induction of autoimmune diseases.

Virus-like Vesicles Expressing Multiple Antigens for Immunotherapy of Chronic Hepatitis B

Infections with hepatitis B virus (HBV) can initiate chronic hepatitis and liver injury, causing more than 600,000 deaths each year worldwide. Current treatments for chronic hepatitis B are inadequate and leave an unmet need for immunotherapeutic approaches. We designed virus-like vesicles (VLV) as self-amplifying RNA replicons expressing three HBV antigens (polymerase, core, and middle surface) from a single vector (HBV-VLV) to break immune exhaustion despite persistent HBV replication. The HBV-VLV induces HBV-specific T cells in naive mice and renders them resistant to acute challenge with HBV. Using a chronic model of HBV infection, we demonstrate efficacy of HBV-VLV priming in combination with DNA booster immunization, as 40% of treated mice showed a decline of serum HBV surface antigen below the detection limit and marked reduction in liver HBV RNA accompanied by induction of HBsAg-specific CD8 T cells. These results warrant further evaluation of HBV-VLV for immunotherapy of chronic hepatitis B.

TCR-like antibodies in cancer immunotherapy

Cancer immunotherapy has been regarded as the most significant scientific breakthrough of 2013, and antibody therapy is at the core of this breakthrough. Despite significant success achieved in recent years, it is still difficult to target intracellular antigens of tumor cells with traditional antibodies, and novel therapeutic strategies are needed. T cell receptor (TCR)-like antibodies comprise a novel family of antibodies that can recognize peptide/MHC complexes on tumor cell surfaces. TCR-like antibodies can execute specific and significant anti-tumor immunity through several distinct molecular mechanisms, and the success of this type of antibody therapy in melanoma, leukemia, and breast, colon, and prostate tumor models has excited researchers in the immunotherapy field. Here, we summarize the generation strategy, function, and molecular mechanisms of TCR-like antibodies described in publications, focusing on the most significant discoveries.

Immune-Escape Hepatitis B Virus Mutations Associated with Viral Reactivation upon Immunosuppression

Hepatitis B virus (HBV) reactivation occurs as a major complication of immunosuppressive therapy among persons who have recovered from acute hepatitis and those who have controlled chronic infection. Recent literature data emphasize the presence of a high degree of S gene variability in HBV isolates from patients who developed reactivation. In reactivated HBV, the most frequently detected mutations belong to the second loop of “a” determinant in HBsAg. These mutations were identified to be immune escape and responsible for vaccine- and diagnostic-escape phenomena. Their emergence clearly provides survival in the presence of a developed humoral immune response and is often associated with impaired serological diagnosis of HBV reactivation. The knowledge of their existence and roles can elucidate the process of reactivation and strongly highlights the importance of HBV DNA detection in monitoring all patients with a history of HBV infection who are undergoing immunosuppression. This review discusses the possible influence of the most frequently found immune-escape mutations on HBV reactivation.

Characteristics of Impaired Dendritic Cell Function in Patients With Hepatitis B Virus Infection

Dendritic cells (DCs) are antigen-presenting cells with a central role in host immune response. This study analyzed gene expression and DC function in hepatitis B virus (HBV) patients, functions impaired because of HBV, and identified the genes related to these functions. Peripheral blood mononuclear cells from 64 HBV patients and 19 healthy controls were analyzed. Peripheral blood DCs were stained with antibodies against human leukocyte antigen-DR/Lin-1/CD123/CD11c and separated into plasmacytoid DCs (pDCs) and myeloid DCs by fluorescence-activated cell sorting. Using an interferon-gamma enzyme-linked immunospot assay, we analyzed antigen-specific response in HBV-infected patients. Regarding DC function, we analyzed antigen-presenting capacity, cell migration capacity, phagocytic capacity, and cytokine production capacity. DC gene expression was analyzed by microarray to identify genes related to DC function. No difference was found in the number of DCs in peripheral blood between healthy participants and HBV patients. In cell-surface marker analysis, CD80, CD83, CD86, CD40, and C-C motif chemokine receptor 7 expression levels in pDCs were related to the HBV-specific T-cell response. DCs from HBV patients exhibited decreases in antigen-presenting capacity, migration capacity, and cytokine production capacity. In gene expression analysis, immune-related genes with greatly reduced expression levels in chronic hepatitis B patients were identified. Of these genes, interleukin (IL)-6 signal transducer (IL6ST) expression level positively correlated with DC surface marker expression level. Adjustment of IL6ST expression level in DCs and treatment with oncostatin M resulted in recovery of DC function. Conclusion: IL6ST expression was identified as one cause of decline in DC function in HBV patients. Adjustment of IL6 family cytokine signaling may be useful for recovering reduced DC function in HBV infection.

Molecular Characterization of Near Full-Length Genomes of Hepatitis B Virus Isolated from Predominantly HIV Infected Individuals in Botswana

The World Health Organization plans to eliminate hepatitis B and C Infections by 2030. Therefore, there is a need to study and understand hepatitis B virus (HBV) epidemiology and viral evolution further, including evaluating occult (HBsAg-negative) HBV infection (OBI), given that such infections are frequently undiagnosed and rarely treated. We aimed to molecularly characterize HBV genomes from 108 individuals co-infected with human immunodeficiency virus (HIV) and chronic hepatitis B (CHB) or OBI identified from previous HIV studies conducted in Botswana from 2009 to 2012. Full-length (3.2 kb) and nearly full-length (~3 kb) genomes were amplified by nested polymerase chain reaction (PCR). Sequences from OBI participants were compared to sequences from CHB participants and GenBank references to identify OBI-unique mutations. HBV genomes from 50 (25 CHB and 25 OBI) individuals were successfully genotyped. Among OBI participants, subgenotype A1 was identified in 12 (48%), D3 in 12 (48%), and E in 1 (4%). A similar genotype distribution was observed in CHB participants. Whole HBV genome sequences from Botswana, representing OBI and CHB, were compared for the first time. There were 43 OBI-unique mutations, of which 26 were novel. Future studies using larger sample sizes and functional analysis of OBI-unique mutations are warranted.

Immune responses of human T lymphocytes to novel hepatitis B virus-derived peptides

Background & aims

Many individuals are infected with hepatitis B virus (HBV) worldwide, and this virus is commonly controlled by treatments with interferon (IFN)-alpha and nucleoside analogues (NA). However, the complete elimination of HBV by these treatments is difficult and, thus, the development of new treatments is needed. Host immune responses are closely involved in the elimination of HBV, suggesting the usefulness of immunotherapy. In the present study, we attempted to identify novel cytotoxic T-lymphocyte (CTL) epitopes that are useful for immunotherapy against HBV.

Methods

CTL epitopes were predicted using computer software. Immune responses to each peptide were evaluated by IFN-γ ELISPOT and cytotoxic assays. The relationships between the immune responses to these newly identified CTL epitopes and the clinical backgrounds of patients and administration of NA were analyzed. Peptides were administered to mice as vaccines and peptide-specific T-cell induction was measured in vivo.

Results

Positive reactions to 10 synthesized peptides were detected in 3 or more patients using the IFN-γ ELISPOT assay, and concentration-dependent cytotoxicity against 2 of these peptides was observed in the cytotoxic assay. Some peptides that correlated with serum ALT, HBsAg, and HBV core-related antigen (HBcrAg) levels were identified. Immune reactions against some peptides were enhanced by the administration of NA. Regarding their effects as a vaccine, peptide-specific T-cells were induced by four peptides in vivo.

Conclusions

Novel HBV epitopes that correlated with HBsAg and HBcrAg levels were identified. These newly identified epitopes may be useful in the analysis of immune responses to HBV and development of immunotherapy against HBV.

Quasispecies characters of hepatitis B virus in immunoprophylaxis failure infants

Hepatitis B vaccination prevents 80-95% of transmission and reduces the incidence of HBV in children. The variations in the a determinant of HBV surface antigen (HBsAg) have been reported to be the most prevalent cause for vaccine or antibody escape. There is a conflicting evidence on as to whether escape mutants arise de novo in infected infants or whether the mutants, that have preexisted maternally, subsequently undergo selective replication in the infant under immune pressure. Here, we report that nearly 65% (55 of 85) vaccination failure in child patients has no amino acid substitution in a determinant as seen by Sanger sequencing. We further employed an Illumina sequencing platform-based method to detect HBV quasispecies in four immunoprophylaxis failure infants and their mothers. In our data, the substitution rate of amino acid located at a determinant is relatively low (< 10%), I/T126A, C124S, F134Y, K141Q, Q129H, D144A, G145V, and N146K, which showed no statistical difference to their mothers, proving that these vaccine escape mutants preexist maternally as minor variants. Besides that, bioinformatical analysis showed that the binding affinity of high variation epitopes (amino acid divergence in mother and their infants > 20%) to related HLA molecules was generally decreased, these traces of immune escape suggesting that immune pressure was present and was effective in all samples.

Genome-wide association study identifies HLA-DR variants conferring risk of HBV-related acute-on-chronic liver failure

OBJECTIVE

Acute-on-chronic liver failure (ACLF) is an extreme condition after severe acute exacerbation of chronic hepatitis B; however, the underlying genetic factors involved in its onset and progression are currently unclear.

DESIGN

We carried out a genome-wide association study among 399 HBV-related ACLFs (cases) and 401 asymptomatic HBV carriers (AsCs, as controls) without antiviral treatment. The initial findings were replicated in four independent case-control sets (a total of 901 ACLFs and 1686 AsCs). The roles of risk variants on clinical traits of ACLF were also analysed.

RESULTS

Among 1300 ACLFs and 2087 AsCs, we identified rs3129859 at human leucocyte antigen (HLA) class II region (chromosome 6p21.32) associated with HBV-related ACLF (combined P _dominant =2.64×10^-20, OR=1.83). Analysis identified HLA-DRB1*12:02 as the top susceptible HLA allele associated with ACLF (p=3.94×10^-6, OR=2.05). The association of rs3129859 was robust in ACLF subgroups (ACLFs with liver cirrhosis, p=1.36×10^-16; ACLFs without liver cirrhosis, p=1.52×10^-7), and patients at low-replicative phase (p=6.36×10^-11, OR=2.29) or HBV e antigen-negative chronic hepatitis B phase (p=1.51×10^-14, OR=1.86). Clinical traits analysis in patients with ACLF showed that the risky rs3129859*C allele was also associated with prolonged prothrombin time, faster progression to ascites development and higher 28-day mortality.

CONCLUSIONS

Our genome-wide association study identified HLA-DR as the major locus for susceptibility to HBV-related ACLF. Our findings highlight the importance of HLA class II restricted CD4+ T-cell pathway on the immunopathogenesis of HBV-related ACLF.

Recognition of Core- and Polymerase-derived immunogenic peptides included in novel therapeutic vaccine by T cells from Chinese chronic hepatitis B patients

Chronic hepatitis B (CHB) is one of the major public health challenges in the world. Due to a strong interplay between specific T-cell immunity and elimination of hepatitis B virus (HBV), efforts to develop novel immunotherapeutics are gaining attention. TG1050, a novel immunotherapy, has shown efficacy in an animal study. To support the clinical development of TG1050 in China, specific immunity to the fusion antigens of TG1050 was assessed in Chinese patients. One hundred and thirty subjects were divided into three groups as CHB patients, HBV spontaneous resolvers, and CHB patients with HBsAg loss after antiviral treatment. HBV-specific T-cell responses to pools of HBV Core or Polymerase genotype D peptides included in TG1050 were evaluated. HBV Core- or Polymerase-specific cells were detected in peripheral blood mononuclear cells (PBMCs) from the different cohorts. The frequencies and intensities of HBV Core-specific immune responses were significantly lower in CHB patients than in HBsAg loss subjects. In CHB patients, a dominant pool derived from Polymerase (Pol1) was the most immunogenic. CHB patients with low viral loads (<10⁶ IU/mL) were more likely to have a positive response specific to the Core peptide pool. Overall, genotype D-derived peptides included in TG1050 could raise broad and functional T-cell responses in PBMCs from Chinese CHB patients infected with genotype B/C isolates. Core-specific immunogenic domains appeared as "hot spots" with the capacity to differentiate between CHB vs HBsAg loss subjects. These observations support the extended application and associated immune monitoring of TG1050 in China.

Hepatitis B virus infection and the immune response: The big questions

Clinical events and the host immune response during hepatitis B virus (HBV) infection are intricately linked. Despite decades of research, important questions concerning the immunopathogenesis of chronic HBV infection remain unanswered. For example, it is unclear which immune parameters facilitate persistence, and if HBV can be completely cleared from the human liver. Recent technological breakthroughs now allow researchers to address these seemingly basic, but essential questions surrounding HBV immunity. It will be important to better define the molecular underpinnings of immune cell function and dysfunction during chronic disease and in controlled infection, with particular focus on the liver, as little information is available on the intrahepatic compartment. In the near future, it may be possible to solve some of the controversy surrounding the immune responses to HBV, and establish the features of both the innate and adaptive arms of the immune system required to achieve sustained control of HBV infection.

The HBV Drugs Work: Now What?

Chemotherapeutic agents for Hepatitis B virus (HBV) suppression work, but only when administered to the patient. They do not appear to promote durable, long-term immunological control. After 3 years of effective anti-HBV therapy, a small percentage of patients maintained good control, manifest by controlled serum liver enzymes, low-level HBV-DNA, and controlled HBsAg concentrations. However, this did not occur in the majority of patients. We need a better understanding of the defects in HBV immunity and how to induce effective reconstitution that will maintain viral suppression, albeit either through innate or adaptive immunity.

Genome-wide identification of blood DNA methylation patterns associated with early-onset hepatocellular carcinoma development in hepatitis B carriers

The etiology of early-onset hepatocellular carcinoma (HCC) among hepatitis B virus (HBV) carriers remains unclear. DNA methylation levels in peripheral leukocytes have been associated with different environmental exposures and immune or inflammatory response. We aimed to identify methylation signatures of peripheral leukocytes that could track hepatitis B progression to HCC, especially for early-onset HCC. We first performed an epigenome-wide association analysis on 48 matched case-control pairs in a nested case-control study within a 22-yr follow-up cohort of HBV carriers. Through this analysis we found that progression to early-onset HCC involved methylation variable positions across the genome, in which a substantial proportion displayed significant variation due to HBV viral load, chronic hepatitis status, and/or leukocyte subtype composition, and these associations were significantly enriched among genes in immune pathways. Methylation at probes cg00300879, cg06872964, and cg07080864, that are located within the proximal promoter of CNKSR1, IFI44L, and PENK, respectively, was validated by bisulfite pyrosequencing and findings were replicated in a case-sibling study of early-onset HCC (134 cases vs. 174 sibling controls). Furthermore, a high methylation score, constructed using the three probes, was predictive for the risk of early-onset HCC in two datasets (adjusted-odds ratios = 0.21-0.32, P ≤ 0.0206). This association was also observed for late-onset HCC (adjusted-odds ratio = 0.42-0.47, P ≤ 0.0194) in a nested case-control study (120 cases vs. 178 controls). In prospective analysis, change in the score was detected 5-9 yr before HCC onset. Blood-based methylation profiling provides new insights into the complexity of virus-host interaction underlying HBV-related HCC, holding promise for the disease risk management. © 2016 Wiley Periodicals, Inc.

New amino acid changes in drug resistance sites and HBsAg in hepatitis B virus genotype H

Long-term treatment with retrotranscriptase (RT) inhibitors eventually leads to the development of drug resistance. Drug-related mutations occur naturally and these can be found in hepatitis B virus (HBV) carriers who have never received antiviral therapy. HBsAg are overlapped with RT domain, thus nucleot(s)ide analogues (NAs) resistance mutations and naturally-occurring mutations can cause amino acid changes in the HBsAg. Twenty-two patients with chronic hepatitis B were enrolled; three of them were previously treated with NAs and 19 were NAs-naïve treated. HBV reverse transcriptase region was sequenced; genotyping and analysis of missense mutations were performed in both RT domain and HBsAg. There was predominance of genotype H. Drug mutations were present in 18.2% of patients. Classical lamivudine resistance mutations (rtM204V/rtL180M) were present in one naïve-treatment patient infected with genotype G. New amino acid changes were identified in drug resistance sites in HBV strains from patients infected with genotype H; rtQ215E was present in two naïve-NAs treatment patients and rtI169M was identified in a patient previously treated with lamivudine. Mutations at sites rt169, rt204, and rt215 resulted in the Y161C, I195M, and C206W mutations at HBsAg. Also, new amino acid changes were identified in B-cell and T-cell epitopes and were more frequent in HBsAg compared to RT domain. In conclusion, new amino acid changes at antiviral resistance sites, B-cell and T-cell epitopes in HBV genotype H were identified in Mexican patients.

Evaluation of hepatitis B surface antibody and specific gamma interferon response in health care workers after vaccination

Background:

Health care workers are at high risk of acquiring hepatitis B virus (HBV) infection through occupational exposure to blood or body fluids. Thus, the assessment of anti-HBs status after immunization is very important.

Objectives:

This study aimed to evaluate the measurement of HBsAb titer and specific gamma interferon response among the vaccinated health care workers in Golestan Hospital, Ahvaz, Iran.

Patients and Methods:

The blood samples of 39 health care workers, including 13 general surgeons, 10 anesthesiologists, 5 neurosurgeons, 3 general physicians, 1 orthopedist, 2 urologist and 5 nurses were collected during June 2013. All the participants had received HBV vaccine. They had received last vaccine dose from 2 months to 14 years ago. Their sera were tested for anti-hepatitis B antibody and HBc-IgG by the ELISA. Also, the evaluation of specific interferon γ response against HBsAg was carried out using ELISA test. The age of health care workers were between 24 and 58 years with the mean age of 34.3 ± 7.4 y.

Results:

Out of 39 sera, 22 (56.41%) had HBsAb titer above 100 IU/mL, 17 (43.6%) had titer below 100 IU/mL, 27 (69.2%) had positive specific HBsAg interferon γ, 8 (20.5%) cases had positive antibody response above 100IU, but negative for specific interferon γ and 3 (7.6%) cases were positive for HBc-IgG.

Conclusions:

Overall, 87.2% of the health care workers had immunity against HBV infection, which showed remarkable immunity response following HBV vaccination. Booster dose of HBV vaccine is recommended for those whose immunity are below 100 IU/mL.

Characterization of overt and occult hepatitis B virus infection among HTLV-1 positive healthy carriers in the Northeast of Iran; AN HTLV-I endemic area

To date, no studies have provided data on hepatitis B virus (HBV) prevalence among asymptomatic, healthy human T-lymphotropic virus (HTLV-I) positive carriers. This sero- and molecular epidemiology study was performed on patients in the Northeast of Iran, which is an endemic area for HTLV-I infection. A total of 109 sera were collected from HTLV-I positive healthy carriers who were admitted to Ghaem Hospital, Mashhad City. All were tested for HBV serology and subsequently, real time PCR was carried out on the samples, regardless of the results of the serology. Standard PCR and direct sequencing were applied on positive samples. All cases were negative for HBsAg, Anti-HBc, and anti-HBs were positive in 34 (31.1%), and 35 (32%) individuals, respectively. There were 19 (17.4%) cases that were positive only for anti-HBs, and they had already received HBV vaccine. 16 (15%) were positive for both anti-HBs and anti-HBc, indicating a past-resolved HBV infection. 18 (16.5%) were isolated as anti-HBc, and 56 (51.3%) were negative for all HBV serological markers. Only one subject (0.9%) had detectable HBV DNA (2153 copy/ml), and assigned as being an occult HBV infection. The low prevalence of HBsAg, despite the high percentage of anti-HBc positive cases, might be related to the suppression effect of HTLV-I on surface protein expression. The low prevalence of HBV infection among HTLV-I positive healthy carriers from an endemic region, indicates that the epidemiology of HTLV-I and HBV coinfection is related to the endemicity of HBV in that region, rather than HTLV-I endemicity.

CD8+ T cell responses specific for hepatitis B virus core protein in patients with chronic hepatitis B virus infection

BACKGROUND

Chronic hepatitis B virus (HBV) infection includes a set of heterogeneous clinical patterns, and core-protein-specific T cell response is important for virus control and disease progression, yet is not well elucidated.

OBJECTIVES

To analyze the phenotypic and functional profiles of HBV-core-protein-specific CD8+ T cells in different clinical patterns of chronic HBV infection.

STUDY DESIGN

A total of 46 HBV patients were recruited and classified according to their clinical status. CD8+ T cell responses in different patterns of chronic HBV infections were tested with flow cytometry using overlapping 15-mer peptides covering HBV core protein. Meanwhile, the CCR7/CD27 phenotypes of these CD8+ T cells were also determined.

RESULTS

Frequencies of gamma interferon (IFN-γ) positive CD8+ T cells in inactive HBV surface antigen (HBsAg) carriers in response to the core protein peptide pools were generally stronger than those of chronic HBV carriers and resolved individuals, especially with regards to peptide pool C13-C24. Moreover, phenotypic studies further highlighted the group of CD8+ CCR7-CD27+ T memory cells, which showed significantly higher levels of IFN-γ secretion in inactive HBsAg carriers than those in chronic hepatitis B patients, chronic HBV carriers and resolved individuals.

CONCLUSIONS

Core-protein-specific T cell response plays an important role in chronic HBV infection. Inactive HBsAg carriers showed a much stronger core-protein-specific cytotoxic T cell response than other types of chronically infected patients. CD8+ CCR7-CD27+ T memory lymphocytes may be crucial in the immune pathogenesis of chronic HBV infection.

An engineered non-toxic superantigen increases cross presentation of hepatitis B virus nucleocapsids by human dendritic cells

Virus like particles (VLPs) are potent immunogens capable of priming strong protective antibody responses due to their repetitive structural arrangement and affinity for specific B cell receptors. By contrast, T cell responses to VLPs can be weak due to inefficient uptake and processing by antigen presenting cells. We report here a novel strategy for increasing the T cell reactivity of a VLP, the nucleocapsid of hepatitis B virus, through covalent coupling of M1, an engineered form of the Streptococcal superantigen SMEZ2, that binds MHC II with high affinity but lacks its T cell mitogenic capability. M1:HBcAg conjugates bound to dendritic cells and were efficiently endocytosed into late endosomes. Human dendritic cells pulsed with M1:HBcAgs stimulated HBV-specific CD8⁺ T cells more effectively than cells pulsed with native capsids indicating that the modified VLP was more effectively cross presented by APCs. Coupling of M1 was also able to induce significantly greater reactivity of human CD4⁺ T cells specific for a common T-helper epitope. These studies indicate the potential of recombinant superantigens to act as flexible molecular adjuvants that can be incorporated into various subunit vaccine platforms leading to enhanced T cell reactivity in humans.

Naturally occurring hepatitis B virus B-cell and T-cell epitope mutants in hepatitis B vaccinated children

To control hepatitis B virus (HBV) infection, a universal HBV vaccination program for infants was launched in Taiwan in 1984. The aim of this study was to investigate the role of B-cell and T-cell epitope variations of HBsAg and polymerase in HBV infection in vaccinated children. One hundred sixty-three sera from vaccinated children were enrolled randomly. HBV serum markers, including hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) and core antigen (anti-HBc), were detected by ELISA. Nucleotide sequences encoding the S and the pre-S regions of HBsAg were analyzed in all HBsAg positive sera. Five children were HBsAg positive. Sequence analysis of S, pre-S, and overlapped polymerase (P) genes showed that HBV isolates of HBsAg-positive vaccinees were variants; no G145R but G145A and other substitutions were found in the “a” determinant. Fifteen, six, and eight amino acid substitutions within B-cell and T-cell epitopes of S, pre-S, and P regions were detected, respectively. Several immune-epitope mutants, such as S45T/A, N131T, I194V, and S207N in S, were detected in all isolates. In conclusion, our results suggested that these naturally occurring immunoepitope mutants, which changed their immunogenicity leading to escape from immune response, might cause HBV infection.

Computational evolutionary analysis of the overlapped surface (S) and polymerase (P) region in hepatitis B virus indicates the spacer domain in P is crucial for survival

Introduction

The Hepatitis B Virus (HBV) genome contains four ORFs, S (surface), P (polymerase), C (core) and X. S is completely overlapped by P and as a consequence the overlapping region is subject to distinctive evolutionary constraints compared to the remainder of the genome. Specifically, a non-synonymous substitution in one coding frame may produce a synonymous substitution in the alternative frame, suggesting a possible conflict between requirements for diversifying and purifying forces. To examine how these contrasting requirements are balanced within this region, we investigated the relationship amongst positive selection sites, conserved regions, epitopes and elements of protein structure to consider how HBV balances the contrasting evolutionary pressures.

Methodology/Results

323 HBV genotype D genome sequences were collected and analyzed to identify sites under positive selection and highly conserved regions. Epitopes sequences were retrieved from previously published experimental studies stored in the Immune Epitope Database. Predicted secondary structures were used to investigate the association between structure and conservation. Entropy was used as a measure of conservation and bivariate logistic regression was used to investigate the relationship between positive selection/conserved sites and epitope/secondary structure regions. Our results indicate: (i) conservation in S is primarily dictated by α-helix elements in the protein structure, (ii) variable residues are mainly located in PreS, the major hydrophilic region (MHR) and the C-terminus, (iii) epitopes in S, which are directly targeted by the host immune system, are significantly associated with sites under positive selection.

Conclusions

The highly variable spacer domain in P, which corresponds to PreS in S, appears to act as a harbor for the accumulation of mutations that can provide flexibility for conformational changes and responding to immune pressure.

Substance abuse, HIV-1 and hepatitis

During the course of human immunodeficiency virus type 1 (HIV-1) disease, the virus has been shown to effectively escape the immune response with the subsequent establishment of latent viral reservoirs in specific cell populations within the peripheral blood (PB) and associated lymphoid tissues, bone marrow (BM), brain, and potentially other end organs. HIV-1, along with hepatitis B and C viruses (HBV and HCV), are known to share similar routes of transmission, including intravenous drug use, blood transfusions, sexual intercourse, and perinatal exposure. Substance abuse, including the use of opioids and cocaine, is a significant risk factor for exposure to HIV-1 and the development of acquired immune deficiency syndrome, as well as HBV and HCV exposure, infection, and disease. Thus, coinfection with HIV-1 and HBV or HCV is common and may be impacted by chronic substance abuse during the course of disease. HIV- 1 impacts the natural course of HBV and HCV infection by accelerating the progression of HBV/HCV-associated liver disease toward end-stage cirrhosis and quantitative depletion of the CD4+ T-cell compartment. HBV or HCV coinfection with HIV-1 is also associated with increased mortality when compared to either infection alone. This review focuses on the impact of substance abuse and coinfection with HBV and HCV in the PB, BM, and brain on the HIV-1 pathogenic process as it relates to viral pathogenesis, disease progression, and the associated immune response during the course of this complex interplay. The impact of HIV-1 and substance abuse on hepatitis virus-induced disease is also a focal point.

Influence of overlapping genes on the evolution of human hepatitis B virus

The aim of this work was to analyse the influence of overlapping genes on the evolution of hepatitis B virus (HBV). A differential evolutionary behaviour among genetic regions and clinical status was found. Dissimilar levels of conservation of the different protein regions could derive from alternative mechanisms to maintain functionality. We propose that, in overlapping regions, selective constraints on one of the genes could drive the substitution process. This would allow protein conservation in one gene by synonymous substitutions while mechanisms of tolerance to the change operate in the overlapping gene (e.g. usage of amino acids with high-degeneracy codons, differential codon usage and replacement by physicochemically similar amino acids). In addition, differential selection pressure according to the HBeAg status was found in all genes, suggesting that the immune response could be one of the factors that would constrain viral replication by interacting with different HBV proteins during the HBeAg(-) stage.

High prevalence of occult hepatitis B virus infection in children born to HBsAg-positive mothers despite prophylaxis with hepatitis B vaccination and HBIG

BACKGROUND & AIMS

Occult hepatitis B virus (HBV) infection is a well-recognized clinical entity characterized by the detection of HBV DNA in serum and/or liver in the absence of detectable hepatitis B surface antigen (HBsAg). The frequency of the diagnosis depends on the relative sensitivity of both HBsAg and HBV DNA assays. We aimed at determining the prevalence of occult HBV infection in a high risk group of children who developed HBV infection despite immunoprophylaxis.

METHODS

The sera of 75 children born to HBsAg-positive mothers previously immunized by HBIG and prophylaxic vaccine regimen were assayed for HBV DNA by real-time PCR. Subsequently, the samples were tested using a sensitive standard PCR, with an independent set of primers for all HBV genes, and analyzed by direct sequencing.

RESULTS

HBV DNA was detected in 21/75 (28%) children, and ranged between 77 and 9240 copies/ml. All were positive for anti-HBs. Five (24%) children were found to be positive for anti-HBc, while anti-HBc-only positive individuals were not observed. Eight isolates (38%) did not carry any mutation. Thirteen infected children (62%) had at least one mutation in regions known to be involved in functional and/or immune epitope activity. Ten had G145R mutations.

CONCLUSIONS

HBV occult infection seems to be relatively frequent in immunized children born to HBsAg-positive mothers. HBsAg negativity is not sufficient to completely exclude HBV DNA presence. These findings emphasize the importance of considering occult HBV infection in hypo-endemic areas.

Lentivirally overexpressed T-bet regulates T-helper cell lineage commitment in chronic hepatitis B patients

Chronic hepatitis B virus (HBV) infection is commonly considered to occur as a result of disturbance of the immune system. T-box expressed in T cells (T-bet) is an essential transcription factor for T helper (Th) cell differentiation and function. The aim of this study was to investigate the effect of T-bet overexpression on Th cell differentiation and the possible mechanism in chronic hepatitis B (CHB) patients. CD4+ T cells from the peripheral blood of 23 CHB patients, 8 acute hepatitis B (AHB) patients and 10 healthy controls were isolated. T-bet mRNA expression of CD4+ T cells was detected by quantitative real-time polymerase chain reaction (PCR). The T-bet DNA fragment was subcloned into the pGC-FU vector containing GFP to generate a recombinant lentiviral vector, pGC-FU-T-bet, while a no-load pGC-FU vector was used as the negative control. After transduction into CD4+ T cells from another 22 CHB patients, the induction of Th1- and Th2-type cytokines was assayed by an enzyme-linked immunosorbent assay (ELISA), and RT-PCR and western blot analysis were used to measure the mRNA and transcription levels of H2.0-like homeobox (HLX1), GATA-3 and STAT-6. T-bet mRNA expression in CD4+ T cells from AHB patients was enhanced compared with CHB patients and healthy controls. Th1-type cytokines and HLX1 expression was upregulated, while Th2-type cytokines and GATA-3 and STAT-6 expression was repressed after lentiviral introduction of T-bet. In conclusion, lentivirally overexpressed T-bet regulates Th cell lineage commitment in CHB patients, which may be mediated by regulating HLX1, GATA-3 and STAT-6 expression.

Immunogenicity and cross-reactivity of a representative ancestral sequence in hepatitis C virus infection

Vaccines designed to prevent or to treat hepatitis C viral infection must achieve maximum cross-reactivity against widely divergent circulating strains. Rational approaches for sequence selection to maximize immunogenicity and minimize genetic distance across circulating strains may enhance vaccine induction of optimal cytotoxic T cell responses. We assessed T cell recognition of potential hepatitis C virus (HCV) vaccine sequences generated using three rational approaches: combining epitopes with predicted tight binding to the MHC, consensus sequence (most common amino acid at each position), and representative ancestral sequence that had been derived using bayesian phylogenetic tools. No correlation was seen between peptide-MHC binding affinity and frequency of recognition, as measured by an IFN-γ T cell response in HLA-matched HCV-infected individuals. Peptides encoding representative, consensus, and natural variant sequences were then tested for the capacity to expand CD8 T cell populations and to elicit cross-reactive CD8 T cell responses. CD8(+) T cells expanded with representative sequence HCV generally more broadly and robustly recognized highly diverse circulating HCV strains than did T cells expanded with either consensus sequence or naturally occurring sequence variants. These data support the use of representative sequence in HCV vaccine design.

IL-2-engineered nano-APC effectively activates viral antigen-mediated T cell responses from chronic hepatitis B virus-infected patients

Impaired function of virus-specific T cells resulting from virus persistence is one of the major mechanisms underlying the development of chronic hepatitis B viral infection. Previously, we found that IL-2 can restore the effector function of T cells rendered tolerant by Ag persistence. However, systemic administration of IL-2 induces organ pathology and expansion of T regulatory cells. In this study, we show that nano-APC with engineered HLA alleles and IL-2 deliver peptide-MHC complexes, costimulatory molecules, and IL-2 to Ag-responding T cells, resulting in enhanced expression of CD25 and activation of TCR signaling pathways, while suppressing PD-1 expression on viral-responding CD8 T cells from chronic hepatitis B virus patients. The enhanced activation of CD4 and CD8 T cells induced by IL-2-nano-APC was Ag dependent and IL-2-nano-APC did not affect T regulatory cells. At a size of 500 nm, the nano-APC effectively induce immune synapse formation on Ag-specific T cells and accumulate as free particles in the lymphoid organs. These attributes of IL-2-nano-APC or other bioadjuvant-engineered nano-APC have profound implications for their use as a therapeutic strategy in the treatment of chronic hepatitis B virus infection or other chronic viral diseases.

Cellular immune responses in patients with hepatitis B surface antigen seroclearance induced by antiviral therapy

Background

The mechanisms by which chronic hepatitis B is completely resolved through antiviral therapy are unknown, and the contribution of acquired T cell immunity to hepatitis B surface antigen (HBsAg) seroclearance has not been investigated. Therefore, we measured the T-cell responses to core and envelope antigens in patients with HBsAg seroclearance.

Methods

Fourteen subjects with HBsAg seroclearance following antiviral treatment for chronic hepatitis B, 7 HBeAg-positive immunotolerant HBV carriers and 9 HBeAg-negative inactive HBsAg carriers were recruited. HBV-specific T-cell responses to recombinant HBV core (rHBcAg) and envelope (rHBsAg) proteins and pools of core and envelope peptides were measured using an ELISPOT assay detecting interferon-gamma and intracellular cytokine staining (ICS) assays detecting interferon-gamma or interleukin 2.

Results

Interferon-gamma ELISPOT assays showed a low frequency of weak responses to the rHBsAg and S peptide pool in the HBsAg seroclearance group, and the response frequency to the rHBcAg and the C peptide pool was higher than to the rHBsAg (P < 0.001) and S peptide pool (P = 0.001) respectively. A higher response frequency to C than S peptide pools was confirmed in the interferon-gamma ICS assays for both CD4+ (P = 0.033) and CD8+ (P = 0.040) T cells in the HBsAg seroclearance group. The responses to C and S antigens in the inactive carriers were similar.

Conclusions

There was a low frequency of CD4+ and CD8+ T cell immune responses to envelope antigens in Chinese subjects with HBsAg seroclearance following antiviral therapy. It is unlikely that these immune responses are responsible for HBsAg seroclearance in these subjects.

Hepatitis B immunology for clinicians

Hepatitis B virus (HBV) is a hepatotrophic DNA virus that causes acute and chronic hepatitis. Despite an effective vaccine, more than 350 million people are chronically infected with HBV worldwide and are at risk for progressive liver disease. There are marked geographic variations in HBV prevalence (ranging from 0.1% to 2% in low prevalence areas and 10% to 20% in high prevalence areas) related to the timing and mode of HBV exposure. In many developed countries, HBV exposure typically occurs in adults via sexual transmission with a low chronicity rate (5%). In regions with high HBV prevalence (eg, Asia, sub-Saharan Africa), HBV exposure tends to occur in the perinatal period (eg, vertical transmission from mother to infant) with a high rate of persistence in the absence of timely vaccination. The course of viral infection is defined by the interplay between the virus and host immune defense. This article introduces the innate and adaptive immune defense mechanisms in general and as related to HBV. In particular, the current concepts regarding the innate and adaptive immune components contributing to the clinical, virologic and therapeutic outcome in acute and chronic hepatitis B are examined.

Full-length hepatitis B virus sequences from naïve patients with fluctuation of viral load during ADV monotherapy

The reasons for adefovir dipivoxil (ADV) treatment failures appear diverse. Few studies have reported full-length hepatitis B virus (HBV) genome in patients with ADV treatment failures. The patients were from a phase III clinical trial that investigated the antiviral response to ADV in China. Seven patients had increase in HBV-DNA (>1 log(10) copies/ml above on-treatment nadir) at week 52. The serum HBV-DNA levels were above 10(4)copies/ml at week 92 in four of them. Sixteen full-length HBV genomes from the four patients at four time points were sequenced using cloning sequencing method. The frequency of substitutions at week 52 was higher than at weeks 28(16 wt) and 92(80). HBV-DNA reduction was correlated negatively with the frequency of substitutions at the three time points. No published ADV-resistant mutations were detected. The mutations, including substitutions in immunogenic epitopes and conserved sites of the polymerase gene, were frequent during ADV treatment. Amino acid deletions in X gene and basal core promoter/pre-core mutations appeared before or during ADV treatment. The substitutions in immunogenic epitopes (mainly of the surface gene) and conserved sites of the polymerase gene other than ADV-resistant mutations may have influenced antiviral efficacy in the study. More potent antiviral drugs may be important to rescue individual patients and for public health safety. It is needed to study how these substitutions influence HBV replication, disease progression, and antiviral treatment efficacy.

HBcAg-pulsed dendritic cell vaccine induces Th1 polarization and production of hepatitis B virus-specific cytotoxic T lymphocytes

AIM

Dendritic cells (DCs) pulsed with HBsAg efficiently reverse the immune tolerance to hepatitis B virus (HBV) and induce HBV-specific cytotoxic T lymphocyte (CTL) responses in transgenic mice and healthy volunteers. However, it is not clear whether HBV core antigen (HBcAg)-pulsed DCs can effectively induce CD4(+) helper T cells polarization into Th1, which contribute to the induction and maintenance of HBV-specific CD8(+) T cells in chronic hepatitis B (CHB) patients. To address this issue, we conducted this study and investigated whether HBcAg-pulsed DCs could polarize Th1 cells and induce an HBcAg-specific CTL response.

METHODS

HBcAg-pulsed DCs were generated from 21 CHB patients. The capacity of the HBcAg-pulsed DC vaccine to stimulate CD4(+) and CD8(+) T cells to produce IFN-gamma and IL-4 was estimated by intercellular cytokine staining, and the HBcAg-pulsed DCs derived from 10 humam leucocyte antigen (HLA)-A2(+) CHB patients were tested for the induction of HBV-specific CTLs from autologous T cells by pentamer staining. The cytotoxicity of these CTLs was evaluated in vitro by flow cytometry.

RESULTS

The HBcAg-pulsed DCs derived from CHB patients exhibited a stronger capacity to stimulate autologous CD4(+) and CD8(+) T cells to release IFN-gamma rather than IL-4, which could induce HBV core 18-27 specific CTLs, suggesting a specific cytotoxicity against T2 cells that had been loaded with the HBV core 18-27 peptide in vitro.

CONCLUSION

HBcAg-pulsed DC vaccine derived from CHB patients efficiently induced autologous T cell polarization to Th1 and generation of HBV core 18-27 specific CTLs.

Hepatitis B virus-specific CD4 T cell immunity after liver transplantation for chronic hepatitis B

Cellular immunity plays an important role in the long-term control of hepatitis B virus (HBV) infection. We studied the changes in HBV-specific CD4 T cell immunity after orthotopic liver transplantation (OLT) for chronic hepatitis B under antiviral prophylaxis. T cell proliferation and interferon-gamma production in response to in vitro challenge with HBV-encoded antigens were tested in 40 OLT recipients without HBV recurrence and in 12 OLT recipients with HBV recurrence more than 1 year after transplantation, and they were compared to 40 subjects with chronic HBV infection and to 23 subjects with self-limited HBV infection. The frequency and magnitude of the HBV-specific CD4 T cell response were significantly lower in 40 OLT recipients with HBV clearance, but the T cell reactivity to mitogen (phytohemagglutinin) and recall antigen (tetanus toxoid) was maintained. In the 12 OLT recipients with HBV recurrence, however, the HBV-specific T cell immunity was enhanced to a level comparable to that of patients with chronic hepatitis B, and the level was dependent on the serum viral load. In conclusion, HBV-specific CD4 T cell immunity is antigen-driven and evanesces with viral clearance, hence providing a favorable milieu for reactivation once prophylaxis is withdrawn. The cellular immunity in recipients with recurrence is not significantly different from that of individuals with chronic hepatitis B.

Adenovirus DNA polymerase is recognized by human CD8+ T cells

Donor lymphocytes have potential as a treatment for adenovirus (Ad) disease in haematopoietic stem cell transplant (SCT) recipients, but better understanding of Ad-specific T-cell responses is required. Most healthy adults exhibit memory T-cell responses to hexon, a capsid protein synthesized late after infection. However, since the Ad E3-19k downregulates major histocompatibility complex (MHC) class I molecules, cytotoxic T cells (CTLs) targeted to early viral proteins may be more effective in eliminating Ad-infected cells in vivo. Here we show that Ad-specific CTLs recognize the early region 2 proteins DNA polymerase (Pol) and DNA-binding protein (DBP). Firstly, memory Ad-specific CD8(+) T cells were amplified from healthy donors by in vitro stimulation with Ad-infected dendritic cells and found to exhibit MHC-restricted cytotoxicity to targets expressing Pol and DBP. Secondly, gamma interferon responses to HLA A2-binding motif peptides from Pol and DBP were directly detected in peripheral blood mononuclear cells (PBMCs) from a recently infected normal donor. Peptide-specific CTLs generated to Pol and DBP epitopes were confirmed to exhibit HLA A2-restricted killing of targets expressing Pol or DBP. Lastly, Pol-epitope-specific T cells were detected at similar or higher frequencies than hexon and DBP in three of three SCT recipients recovering from invasive Ad disease. Pol epitopes were well conserved among different Ad serotypes. Therefore, Pol is a promising target for immunotherapy of Ad disease.

[Hepatitis B core antigen expression pattern predicts response to lamivudine therapy in patients with chronic hepatitis B]

BACKGROUNDS/AIMS

Negative hepatitis B core antigen (HBcAg) staining in hepatocytes is indicative of viral replication by an active immune response. HBcAg is expressed mainly in the cytoplasm in patients with active hepatitis and hepatocyte regeneration, and mainly in the nuclei of hepatocytes in patients with minimal liver injury in the absence of hepatocyte regeneration. The aim of this study was to elucidate whether the existence and expression pattern of HBcAg predicts the response to antiviral treatment.

METHODS

The study involved 58 patients with biopsy-proven chronic hepatitis B who were treated with lamivudine. Hepatitis B e antigen (HBeAg), antibody to HBeAg, hepatitis B virus DNA, and alanine aminotransferase in serum were recorded every 3 months. The inflammation grade and the fibrosis stage of chronic hepatitis were scored from 0 to 4 according to lobular inflammation, portal inflammation, periportal inflammation, and fibrosis.

RESULTS

The 58 patients included 49(84%) HBcAg-positive patients, with HBcAg staining confined to the cytoplasm in 15(31%) and in both cytoplasm and nuclei in 34(69%). The grade of lobular inflammation and the total histology score were significantly higher in patients with cytoplasmic expression of HBcAg than in HBcAg-negative patients (lobular inflammation: 2.9 vs 2.1, P=0.02; total histology score: 12.2 vs 10.3, P=0.04). The virologic responses at 3, 6, 9, and 12 months differed significantly between the cytoplasmic and mixed expression groups (P<0.01).

CONCLUSIONS

The expression pattern of HBcAg (including its possible absence) before initial therapy appears to predict the response to antiviral treatment.

Cellular immune responses in hepatitis B virus e antigen negative chronic hepatitis B

The immunopathogenesis of hepatitis B e antigen (HBeAg) negative chronic hepatitis B (CHB) virus (HBV) infection has not been adequately investigated. We studied the cellular immune responses of peripheral lymphocytes using proliferating assays, intracellular cytokine staining (ICS) and ELISPOT interferon-gamma (IFN-gamma) assays after non-specific and specific stimulation with whole HBV proteins and synthetic peptides. Thirty patients with HBeAg negative CHB, eleven HBsAg inactive carriers, nine patients with acute hepatitis B and 22 healthy controls were included in the study. Patients with HBeAg negative CHB demonstrated an increased number of peripheral CD8+ T cells while their peripheral blood mononuclear cells showed increased proliferation after in vitro stimulation with overlapping hepatitis B core derived peptides and an envelope derived epitope (HBs 182-191 aa), similar to those observed in acute hepatitis B. Using ICS, we found an expanded population of IFN-gamma producing T lymphocytes, CD4+ and CD8+, after non-specific stimulation, in HBeAg negative CHB compared to all other groups. HBeAg negative CHB and acute hepatitis B patients had a similarly increased number of core specific T cells measured by the IFN-gamma assays. Inactive HBsAg carriers showed minimal proliferative responses overall while they exhibited an increased number of envelope specific effector T cells (measured by ICS). In conclusion, we showed that overall CD4+ T cell responses from patients with HBeAg negative CHB were comparable to those of acute hepatitis B, while inactive HBsAg carriers despite their limited proliferative capacity the effector activity of their peripheral T cells was maintained.

Impact of viral replication inhibition by entecavir on peripheral T lymphocyte subpopulations in chronic hepatitis B patients

BACKGROUND

To investigate dynamic fluctuations of serum viral load and peripheral T-lymphocyte subpopulations of chronic hepatitis B patients and their correlation during entecavir therapy.

METHODS

Fifty-five patients received entecavir 0.5 mg/d therapy. Serum HBV DNA load was measured by Real-Time-PCR, and the levels of peripheral T-lymphocyte subpopulations by flow cytometry biweekly, every four weeks and every eight weeks during weeks 1-12, 13-24 and 24-48, respectively. Multilevel modelling was used to analyse the relationship between these variables.

RESULTS

Of the 55 patients, all HBeAg positive and with detectable HBV DNA, the majority (81.8%) had serum levels of HBV DNA over 10(7) copies per milliliter. HBV viral load dropped sharply during the first two weeks. In 28 and 43 patients, the level became undetectable from week 24 and 48, respectively. Using pre-therapy level as the reference, a significant decrease in CD8+ T cells and increase in CD4+ T cells were found from week 12. Both parameters and CD4+/CD8+ ratio steadily improved throughout the 48 weeks. Multilevel analyses showed that the level of decrement of HBV DNA was associated with the increment of T-lymphocyte activities only in the later period (4-48 week). After 4 weeks of therapy, for each log10 scale decrement of HBV DNA, the percentage of CD4+ lymphocyte was increased by 0.49 and that of CD8+ decreased by 0.51.

CONCLUSION

T-lymphocyte subpopulations could be restored partially by entecavir treatment in patients with chronic hepatitis B concurrently with reduction of viremia.

Subacute cutaneous lupus erythematosus and interstitial myositis occurring with hepatitis B infection: response to antiviral therapy with lamivudine

Lupus erythematosus (LE) is a multisystem inflammatory disease resulting from an altered T- and B-cell response. Among various pathogenic factors, viral infections have been implicated in LE exacerbation. We describe a patient with acute onset of subacute cutaneous lupus erythematosus (SCLE) and interstitial myositis with mitochondrial changes in the context of an associated hepatitis B infection and the response of myositis to antiviral treatment with lamivudine. Viral vectors may play an important role in LE. A hitherto undescribed myositis with mitochondrial changes was associated with hepatitis B infection and SCLE and improved with antiviral treatment.

Hepatitis B virus DNA is more powerful than HBeAg in predicting peripheral T-lymphocyte subpopulations in chronic HBV-infected individuals with normal liver function tests

AIM: To investigate the peripheral T-lymphocyte subpopulation profile, and its correlations with hepatitis B virus (HBV) replication level in chronic HBV-infected (CHI) individuals with normal liver function tests (LFTs).

METHODS: Frequencies of T-lymphocyte subpopu-lations in peripheral blood were measured by flow cytometry in 216 CHI individuals. HBV markers were detected with ELISA. Serum HBV DNA load was assessed with quantitative real-time PCR. Information of age at HBV infection, and maternal HBV infection status was collected. ANOVA linear trend test and linear regression were used in statistical analysis.

RESULTS: CHI individuals had significantly decreased relative frequencies of CD3⁺, CD4⁺ subpopulations and CD4⁺/CD8⁺ ratio, and increased CD8⁺ subset percentage compared with uninfected individuals (all P < 0.001). There was a significant linear relationship between the load of HBV DNA and the parameters of T-lymphocyte subpopulations (ANOVA linear trend test P < 0.01). The parameters were also significantly worse among individuals whose mothers were known to be HBV carriers, and those having gained infection before the age of 8 years. In multiple regressions, after adjustment for age at HBV infection and status of maternal HBV infection, log copies of HBV DNA maintained its highly significant predictive coefficient on T-lymphocyte subpopulations, whereas the effect of HBeAg was not significant.

CONCLUSION: HBV DNA correlates with modification in the relative T-lymphocyte subpopulation frequencies. High viral load is more powerful than HBeAg in predicting the impaired balance of T-cell subsets.