How can the cellular immune response control hepatitis B virus replication?

Restoring, releasing or replacing adaptive immunity in chronic hepatitis B

Multiple new therapeutic approaches are currently being developed to achieve sustained, off-treatment suppression of HBV, a persistent hepatotropic infection that kills ~2,000 people a day. A fundamental therapeutic goal is the restoration of robust HBV-specific adaptive immune responses that are able to maintain prolonged immunosurveillance of residual infection. Here, we provide insight into key components of successful T cell and B cell responses to HBV, discussing the importance of different specificities and effector functions, local intrahepatic immunity and pathogenic potential. We focus on the parallels and interactions between T cell and B cell responses, highlighting emerging areas for future investigation. We review the potential for different immunotherapies in development to restore or release endogenous adaptive immunity by direct or indirect approaches, including limitations and risks. Finally, we consider an alternative HBV treatment strategy of replacing failed endogenous immunity with infusions of highly targeted T cells or antibodies.

JOINT IMPACTS OF THERAPY DURATION, DRUG EFFICACY AND TIME LAG IN IMMUNE EXPANSION ON IMMUNITY BOOSTING BY ANTIVIRAL THERAPY

Antiviral drug therapy that targets on boosting virus-specific immune response has become very promising in controlling the virus, especially when completely eradicating the virus from the host turns out to be difficult. Using a concrete viral infection model that incorporates the time lag needed for the expansion of immune cells, we numerically explored the joint impacts of the duration of therapy, the efficacy of the drugs and the time lag in immune expansion on immunity boosting for a single phase of therapy. Our findings reveal that a single phase of therapy can establish sustained immunity if the therapy is stopped in a suitable range of timing and large time lag in the expansion of immune cells and too strong or too weak therapy would lead to a failure in immunity boosting. Our findings may provide some insights on designing efficient and rational therapy strategies in boosting sustained immunity.

Immune response- and viral control-related pathways in the progression of chronic hepatitis B

BACKGROUND

Chronic hepatitis B (CHB) is a complicated and dynamic course, and is associated with advanced liver disease. Host immune response against viral infection plays a pivotal role in the progression of CHB. However, it is still uncharted that how the hepatic transcriptomes in patients with CHB are correlated with the clinical phases.

OBJECTIVE

This study aimed to identify the specific sub-networks across various phases of CHB and infer potential pathways for phenotypic outcome prediction.

METHODS

In this study, we performed the pairwise comparisons of the hepatic transcriptomes of CHB patients under different phases, and constructed the differential co-expression networks (DCNs). We firstly identified the critical genes from each DCN according to the adjacency matrix of the network. Then, the specific sub-networks were digged by iteratively affiliating genes that can increase the classification accuracy, using a snow-ball sampling strategy. Permutation test was implemented to determine the statistical significance of these sub-networks. Finally, each sub-network was given a most significant functional pathway.

RESULTS

We constructed 3 DCNs by pairwise comparing the hepatic transcriptomes among three CHB phases, and systemically tracked 1, 1 and 2 specific sub-networks and pathways, respectively. Relative to immune tolerant phase, TGF-beta receptor signaling in EMT (epithelial to mesenchymal transition) pathway was significantly changed in the immune clearance phase, and nuclear receptor transcription pathway and adenylate cyclase activating pathway were altered in inactive carrier state. The host genes related to DNA strand elongation showed significant difference between the immune clearance phase and inactive carrier state.

CONCLUSIONS

By pairwise comparing the hepatic transcriptomes of CHB patients under a network view, several immune- and viral control-related pathways were identified in this study. These results might serve as a foundation for characterizing the host transcriptomes responded to CHB infection, and hold clues for the development of potential targets for disease control.

Characterization of hepatitis B virus surface antigen variability and impact on HBs antigen clearance under nucleos(t)ide analogue therapy

For hepatitis B virus (HBV)-related chronic infection under treatment by nucleos(t)ide analogues (NUCs), HBsAg clearance is the ultimate therapeutic goal but very infrequent. We investigated how HBV envelope protein variability could lead to differential HBsAg clearance on NUCs. For 12 HBV genotype D patients receiving NUCs, six resolvers (HBsAg clearance) were compared to six matched nonresolvers (HBsAg persistence). PreS/S amino acid (aa) sequences were analysed with bioinformatics to predict HBV envelope antigenicity and aa covariance. To enrich our analyses on very rare resolvers, these were compared with other HBV genotype D strains in three characterized clinical cohorts including common chronically infected patients. The sT125M+sP127T combination was observed in four nonresolvers of six, corroborated by aa covariance analysis, associated with a lower predicted antigenicity than sT125T+sP127P. Concordant features within this HBV key functional domain, at positions 125 and 127, were reported from two of the three comparative cohorts. In our hands, a lower ELISA reactivity of HBV-vaccinated mice sera was observed against the sT125M mutant. In the S gene, 56 aa changes in minor variants were detected in non-resolvers, mainly in the major hydrophilic region, vs 28 aa changes in resolvers. Molecular features in patients showing HBsAg persistence on NUCs argue in favour of a different aa pattern in the HBV S gene compared to those showing HBsAg clearance. In nonresolvers, a decrease in HBs 'a' determinant antigenicity and more frequent mutations in the S gene suggest a role for the HBV envelope characteristics in HBsAg persistence.

IL-18, TNF, and IFN-γ alleles and genotypes are associated with susceptibility to chronic hepatitis B infection and severity of liver injury

This study evaluated the association of polymorphisms in the IL-18 (-607C/A and -137C/G), IFNγ (+874 A/T), and TNF (-238 A/G and -308 A/G) genes with susceptibility to HBV infection and severity of liver injury. A total of 259 chronic HBV-infected patients followed at the University Hospital, Faculty of Medicine of Ribeirão Preto, São Paulo, Brazil, and 202 healthy individuals were studied. Four Single Nucleotide Polymorphisms (SNPs) were amplified by Polymerase Chain Reaction (PCR). Liver biopsy was performed in 212 HBV-infected patients and classified according to severity of liver fibrosis (scores 0-4) and necroinflammatory activity (HAI scores 0-18). TNF-308*A allele (P < 0.001; OR = 2.16) and TNF -308 AA genotype (P = 0.026; OR = 5.43) were associated with susceptibility to HBV infection. An association was found between severe liver fibrosis when compared to mild fibrosis and the following polymorphisms: Alleles IL-18 -137*G (P = 0.004; OR = 3.45), TNF -308*A (P < 0.001; OR = 3.39), and IFNγ +874*T (P = 0.029; OR = 1.85) and IL-18 -137 GG genotype (P = 0.009; OR = 3.70). No significant association was found between IL-18 (-607 A/C) polymorphism and severity of liver fibrosis. Alleles IL-18 -137*G (P = 0.028; OR = 2.64) and TNF-308*A (P = 0.002; OR = 3.06) and IL-18 -137 GG genotype (P = 0.011; OR = 4.20) were associated with severe necroinflammatory activity (HAI>12) when compared to mild necroinflammatory activity (HAI 1-8). The results suggest that IL-18 -137C/G, TNF-308 G/A and IFNγ +874 A/T SNPs were associated to more severe liver injury in chronic HBV infection. TNF -308*A allele and TNF -308 AA genotype could play a role in the susceptibility to HBV infection.

Polymorphisms in CISH gene are associated with persistent hepatitis B virus infection in Han Chinese population

BACKGROUND AND AIM

Cytokine-inducible SRC homology 2 domain protein (CISH) is the first member of the suppressors of cytokine signaling (SOCS) protein family. An association between multiple CISH polymorphisms and susceptibility to infectious diseases has been reported. This study aimed to investigate the possible association of these single nucleotide polymorphisms (SNPs) in CISH gene with different outcomes of Hepatitis B virus (HBV) infection.

METHODS

1019 unrelated Chinese Han subjects, including 240 persistent asymptomatic HBV carriers, 217 chronic hepatitis B patients, 137 HBV-related liver cirrhosis patients, and 425 cases of spontaneously recovered HBV as controls, were studied. Four SNPs (rs622502, rs2239751, rs414171 and rs6768300) in CISH gene were genotyped with the snapshot technique. Transcriptional activity of the CISH promoter was assayed in vitro using the dual-luciferase reporter assay system.

RESULTS

At position rs414171, A allele and AA genotype frequencies were significantly higher in the HBV-resolved group as compared to the persistent HBV infection group. At position rs2239751, TT genotype was further observed in the HBV-resolved group. Using asymptomatic HBV carriers as controls, our results indicated that the rs414171 and rs2239751 polymorphisms were unrelated to HBV progression. The other two SNPs (rs622502 and rs6768300) showed no association with persistent HBV infection. Haplotype analysis revealed that the GGCA haplotype was associated with spontaneous clearance of HBV in this population. Moreover, luciferase activity was significantly higher in the PGL3-Basic-rs414171T construct as compared to the PGL3-Basic-rs414171A construct (p<0.001).

CONCLUSION

Two SNPs (rs414171 and rs2239751) in the CISH gene were associated with persistent HBV infection in Han Chinese population, but not with HBV progression.

Influence of B cells in liver fibrosis associated with hepatitis B virus harboring basal core promoter mutations

The development of the liver disease in chronic hepatitis B with common viral variants can be determined through the interaction between the virus and the host immune response. B cells constitute half of the intrahepatic lymphocyte population with an impact on fibrosis. A proliferation-inducing ligand (APRIL) has been shown to have a co-stimulatory activity on B cells. For this study HBV DNA was amplified and then sequenced to show the presence of the basal core promoter (BCP) mutations in the serum from 57 patients with chronic hepatitis B. The range of IgD-positive B cells was detected by immunohistochemistry in liver biopsies; and patients serum was assayed for APRIL levels by enzyme immunoassay. Twenty-seven patients (47.4%) harbored the A1762T-G1764A BCP mutations. Coefficients of logistic regression showed that the effect of increasing IgD-positive B cells in rising odds of the liver disease is the same in the patients with BCP mutation A1762T-G1764A and in the patients without mutation, nevertheless the effect of APRIL is not similar in these two groups of patients. Logistic regression in patients with BCP A1762T-G1764A mutations demonstrated that increasing one score of APRIL decreased the odds of fibrosis stage about 8%. These results suggest that in infection with viral variants of hepatitis B virus, the population of IgD-positive B cells may play a decisive role in later stages of the liver disease which is reduced by APRIL in chronic hepatitis patients with BCP mutations.

Clinical impact of hepatitis B and C virus envelope glycoproteins

Chronic infection by either hepatitis B virus (HBV) or hepatitis C virus (HCV) share epidemiological characteristics with risks for development of severe complications such as liver cirrhosis and hepatocellular carcinoma. HBV and HCV also share a high genetic variability. Among highly variable regions, viral genes encoding surface proteins (hepatitis B surface antigen, E1/E2 HCV glycoproteins) play key roles in the stimulation of the host-related immune response and viral entry into hepatocytes. Specific segments of HBV envelope proteins (preS1, “a” determinant) are crucial in the entry process into permissive cells. HCV entry is a complex multistep process involving multiple cell cofactors (glycosaminoglycans, low density lipoprotein receptor, SR-B1, CD81, claudin-1, occludin, EGFR, EphA2) in the interaction with HCV E1/E2 envelope glycoproteins. In vitro both viruses can be controlled by antibody-mediated neutralization targeting viral envelope, also essential in preventing HBV infection in vivo as observed through successful vaccination using HBs antigen. But preventive vaccination and/or therapeutic pressure can influence HBV and HCV variability. For HBV, the patterns of antiviral drug resistance in chronic hepatitis are complex and the original pol/S gene overlap has to be taken into account. Treatment-induced HBV mutations in pol could indeed generate S mutants with subsequent modified antigenicity or increased cancer induction. Variability of HBV and HCV envelope proteins combining high exposure to selective pressures and crucial functional roles require investigation in the context of diagnostic, vaccination and treatment tools. In this editorial a synthesis is performed of HBV and HCV envelope properties at the entry step and as antigenic proteins, and the subsequent clinical impact.

Association of markers of chronic viral hepatitis and blood mercury levels in US reproductive-age women from NHANES 2001-2008: a cross-sectional study

BACKGROUND

Methylmercury (MeHg) is a neurotoxin primarily found in seafood; exposures in reproductive-age women are of concern due to vulnerability of the developing fetus. MeHg is mainly eliminated via an enterohepatic cycle involving the liver and gallbladder. Dysfunction in these organs has been associated with slower MeHg elimination in laboratory animals. We hypothesized that women testing positive for chronic hepatitis B (HBV) or C (HCV), both associated with risk of longer-term liver and gallbladder impairment, would have higher total blood mercury (TBHg) concentrations than those negative for the viruses, reflecting slower MeHg elimination.

METHODS

Geometric mean (GM) TBHg levels from a representative sample of over 5,000 seafood-consuming, reproductive-age women from eight years (2001-2008) of the US NHANES survey were compared by viral hepatitis status (as determined by serological assay) using multiple linear regression. Adjustment was made for estimated MeHg intake from seafood consumption, social and demographic variables and other predictors.

RESULTS

Women with chronic HBV had 1.52 (95% CI 1.13, 2.05, p < 0.01) times the GM TBHg of women who had not come into contact with the virus. The positive association was strongest in those with most severe disease. A modest negative association was found with HCV markers.

CONCLUSIONS

While study design prevents inferences on causality, the finding that MeHg biomarkers differ by hepatitis status in this population suggests viral hepatitis may alter the pace of MeHg elimination. Offspring of HBV-infected seafood-consuming women may be at higher risk of MeHg-induced developmental delays than offspring of those uninfected. Possible reasons for the unanticipated negative association with HCV are explored.

Treatment induced seroconversion to HBsAb following HBV reactivation in the immunosuppressed haematology and oncology patient: a clinical survey of 5 cases in Catania, Italy

BACKGROUND

In onco-haematological patients inactive or occult HBV infection may be reactivated as a result of disease-related immuno-suppression and/or chemotherapy with rituximab.

OBJECTIVES

This study reports the clinical features of five patients affected by onco-haematological disorders who experienced hepatitis B reactivation.

STUDY DESIGN

From 2005 to 2010, five onco-haematological patients with hepatitis B reactivation were admitted to the department of Infectious Diseases, Ferrarotto Hospital, Catania, Italy.

RESULTS

At the time of onco-haematological disease diagnosis, 3 patients were HBcAb positive; 1 HBsAb and HBcAb positive; and 1 HBsAg positive, HBV DNA negative. None of the patients received hepatitis B prophylaxis. Reactivation was observed following chemotherapy. One patient was treated with lamivudine, 2 with tenofovir and 2 with telbivudine. Following treatment all patients achieved undetectable HBV DNA and normalization of transaminases. Three patients, those treated with lamivudine and tenofovir, cleared HBsAg and developed protective titres of HBsAb. The remaining patients, who were treated with telbivudine, were HBV DNA negative and HBsAg positive one at 27 months and the other at 5 months of therapy. Treatment thus continued in these patients.

CONCLUSION

HBV reactivation can be a severe complication in onco-haematological patients undergoing chemotherapy with rituximab. In our experience all nucleos(t)ide analogues were safe and effective. Three patients seroconverted to HBsAb. This may be as a result of the antivirals enhancing the immune response to HBV. A similar role may also be played by immune recovery following the withdrawal of immune-suppressive treatment. This report confirms the importance of anti-viral prophylaxis in patients with a high risk of HBV reactivation.

Differences in peripheral T-cell subsets among different clinical types of hepatitis B patients

AIM: To observe the differences in T-lymphocyte subsets among different clinical types of chronic hepatitis B (CHB) patients.

METHODS: Forty-seven CHB patients, 30 HBV carriers, 26 severe hepatitis patients, and 34 patients with other diseases that do not affect T-lymphocyte subsets (including 15 patients with hypertension, 9 patients with coronary heart disease, and 10 patients with non-steroidal anti-inflammatory drug-related peptic ulcer) were included in the study. All the patients were treated at the Affiliated Hospital of Guiyang Medical College from September 2006 to March 2009. The peripheral T-lymphocyte subsets in these patient were determined by flow cytometry.

RESULTS: The number of CD3⁺, CD4⁺ and CD8⁺ T lymphocytes and the percentages of CD3⁺ and CD4⁺ T lymphocytes in peripheral blood as well as CD4⁺/CD8⁺ ratio in CHB patients, HBV carriers and serious hepatitis patients were significantly lower than those in control patients (all P < 0.05 or 0.01). In contrast, the percentages of CD8⁺ T lymphocytes in peripheral blood in CHB patients, HBV carriers and serious hepatitis patients were significantly higher than those in control patients (all P < 0.05 or 0.01). Significant differences were also noted in the above parameters among CHB patients, HBV carriers and serious hepatitis patients.

CONCLUSION: Varying degrees of decreased cellular immune function and immune dysregulation are noted in various clinical types of CHB patients.

Transfusion of autologous cytokine-induced killer cells inhibits viral replication in patients with chronic hepatitis B virus infection

Adoptive immune transfer plays an important role in clearance of hepatitis B virus (HBV) in chronic hepatitis B (CHB) patients. However, it is unclear whether cytokine-induced killer (CIK) cells could suppress HBV replication in CHB patients, especially if drug resistance develops. In this study, functional CIK cells were efficiently generated from 21 CHB patients and were transfused in an autologous manner. We found that CIK cells from the CHB patients displayed substantial proliferation and function. Administration of the CIK cells closely correlated with the decrease in the serum HBV load and improvement in liver function in some patients. The virological response rate in patients with baseline serum alanine aminotransferase (ALT) levels of >40 U/L was higher than that in patients with baseline serum ALT levels of < or = 40 U/L. Moreover, patients who had HBeAg loss or showed seroconversion generally had baseline serum ALT levels of >40 U/L. No serious side effects were observed. This protocol represents an alternative immune therapeutic strategy for the disease.

The pathogenesis of liver disease in the setting of HIV–hepatitis B virus coinfection

There are many potential reasons for increased liver-related mortality in HIV–hepatitis B virus (HBV) coinfection compared with either infection alone. HIV infects multiple cells in the liver and might potentially alter the life cycle of HBV, although evidence to date is limited. Unique mutations in HBV have been defined in HIV–HBV-coinfected individuals and might directly alter pathogenesis. In addition, an impaired HBV- specific T-cell immune response is likely to be important. The roles of microbial translocation, immune activation and increased hepatic stellate cell activation will be important areas for future study.

A Systematic Review of T-cell Epitopes in Hepatitis B Virus: Identification, Genotypic Variation and Relevance to Antiviral Therapeutics

Background

The immune response to hepatitis B virus (HBV) is important for both viral control and disease pathogenesis. A detailed understanding of the HBV-specific T-cell responses may potentially lead to novel therapeutic strategies for HBV.

Methods

All English language journal articles (including articles in press) up to October 2007 were retrieved using searches of MEDLINE, EMBASE and the Cochrane Controlled Trial Registry. An extensive database of HBV sequences (SeqHepB) and GenBank were used to assess the degree of sequence variation in each epitope. The new standardized nomenclature for HBV amino acid position number was applied to all previously defined epitopes.

Results

Forty-four HBV-specific human leukocyte antigen (HLA) class I restricted and 32 HBV-specific HLA class II restricted epitopes have been defined and have been identified in all HBV genes. The majority of HLA class I restricted epitopes have been defined in HLA-A2-positive individuals in the setting of acute HBV infection. There is significant sequence variation of these epitopes within and between HBV genotypes. Newer HBV immunotherapeutics appear promising but are still in early phases of development.

Conclusions

Identification of HBV-specific epitopes in non-HLA-A2-positive individuals and recognition of genotypic variation across epitopes are important for the future development of novel immunotherapeutic strategies for the management of chronic HBV infection.

A chronic viral infection model with immune impairment

In this paper, a chronic viral infection model with cell-mediated immunity and immune impairment is proposed and studied, under the assumption that the presence of the antigen can both stimulate and impair immunity. It is shown that the virus persists in the host if the basic reproductive ratio of the virus is greater than 1. The immune cells persist when there is only one positive equilibrium. The system can exhibit two positive equilibria if the basic reproductive ratio of the virus is above a threshold. This allows a bistable behavior, and the immune cells persist or die out, i.e., infection will result in disease or immune control outcome, depending on the initial conditions. By theoretical analysis and numerical simulations, we show that therapy could shift the patient from a disease progression to an immune control outcome, despite that the therapy is not necessarily lifelong. This would allow the immune response to control the virus in the long term even in the absence of continued therapy.

Blocking intrahepatic deletion of activated CD8+ T cells by an altered peptide ligand

BACKGROUND

Activated CD8(+) T cells are retained by the healthy liver where the majority undergo apoptosis. The intrahepatic apoptosis of activated CD8(+) T cells is enhanced by the presence of SIINFEKL peptide. It is of great interest to identify strategies for maintaining intrahepatic T cell number and function in the presence of SIINFEKL peptides.

AIM

Our aim was to test if low affinity peptides can block SIINFEKL peptide induced T cell deletion.

METHODS

We used an in vivo model of intrahepatic CD8(+) T cell deletion with peptides of different affinities.

RESULTS AND DISCUSSION

We show that the intrahepatic deletion of CD8(+) T cells by SIINFEKL peptide results in loss of in vivo cytotoxic T lymphocyte function. In contrast we show that a low affinity peptide (G4) does not result in intrahepatic deletion of CD8(+) T cells. High concentrations G4 peptide can however block intrahepatic deletion of activated CD8(+) T cells, and prevent loss of in vivo cytotoxicity due to SIINFEKL peptide. This is the first demonstration of blocking of SIINFEKL peptide induced CD8(+) T cell deletion in the liver, with enhancement of in vivo cytotoxicity.

Variability and conservation in hepatitis B virus core protein

Background

Hepatitis B core protein (HBVc) has been extensively studied from both a structural and immunological point of view, but the evolutionary forces driving sequence variation within core are incompletely understood.

Results

In this study, the observed variation in HBVc protein sequence has been examined in a collection of a large number of HBVc protein sequences from public sequence repositories. An alignment of several hundred sequences was carried out, and used to analyse the distribution of polymorphisms along the HBVc. Polymorphisms were found at 44 out of 185 amino acid positions analysed and were clustered predominantly in those parts of HBVc forming the outer surface and spike on intact capsid. The relationship between HBVc diversity and HBV genotype was examined. The position of variable amino acids along the sequence was examined in terms of the structural constraints of capsid and envelope assembly, and also in terms of immunological recognition by T and B cells.

Conclusion

Over three quarters of amino acids within the HBVc sequence are non-polymorphic, and variation is focused to a few amino acids. Phylogenetic analysis suggests that core protein specific forces constrain its diversity within the context of overall HBV genome evolution. As a consequence, core protein is not a reliable predictor of virus genotype. The structural requirements of capsid assembly are likely to play a major role in limiting diversity. The phylogenetic analysis further suggests that immunological selection does not play a major role in driving HBVc diversity.

Reduced hepatitis B virus (HBV)-specific CD4+ T-cell responses in human immunodeficiency virus type 1-HBV-coinfected individuals receiving HBV-active antiretroviral therapy

Functional hepatitis B virus (HBV)-specific T cells are significantly diminished in individuals chronically infected with HBV compared to individuals with self-limiting HBV infection or those on anti-HBV therapy. In individuals infected with human immunodeficiency virus type 1 (HIV-1), coinfection with HBV is associated with an increased risk of worsening liver function following antiviral therapy and of more rapid HBV disease progression. Total HBV-specific T-cell responses in subjects with diverse genetic backgrounds were characterized by using a library of 15-mer peptides overlapping by 11 amino acids and spanning all HBV proteins. The magnitude and breadth of CD4(+) and CD8(+) T-cell responses to HBV in peripheral blood were examined by flow cytometry to detect gamma interferon production following stimulation with HBV peptide pools. Chronic HBV carriers (n = 34) were studied, including individuals never treated for HBV infection (n = 7), HBV-infected individuals receiving anti-HBV therapy (n = 13), and HIV-1-HBV-coinfected individuals receiving anti-HBV therapy (n = 14). CD4(+) and CD8(+) HBV-specific T-cell responses were more frequently detected and the CD8(+) T-cell responses were of greater magnitude and breadth in subjects on anti-HBV treatment than in untreated chronic HBV carriers. There was a significant inverse correlation between detection of a HBV-specific T-cell response and HBV viral load. HBV-specific CD4(+) and CD8(+) T-cell responses were significantly (fivefold) reduced compared with HIV-specific responses. Although, the frequency and breadth of HBV-specific CD8(+) T-cell responses were comparable in the monoinfected and HIV-1-HBV-coinfected groups, HBV-specific CD4(+) T-cell responses were significantly reduced in HIV-1-HBV-coinfected individuals. Therefore, HIV-1 infection has a significant and specific effect on HBV-specific T-cell immunity.

Efficacy of hepatitis B vaccination and interferon-alpha-2b combination therapy versus interferon-alpha-2b monotherapy in children with chronic hepatitis B

BACKGROUND

Although interferon (IFN) has been approved in the treatment of chronic hepatitis B in children, it is effective only in 30-40% of patients. In some studies it has been suggested that therapeutic use of anti-hepatitis B virus (HBV) vaccine may be beneficial in patients with chronic hepatitis B. The aim of the present study was to compare the efficacy of hepatitis B vaccination and IFN-alpha-2b in combination and IFN-alpha-2b monotherapy in children with chronic hepatitis B.

METHODS

Fifty treatment-naive children with chronic hepatitis B infection were randomly assigned to receive either 5 million units/m(2) recombinant IFN-alpha-2b subcutaneously three times per week for 9 months, and pre-S2/S vaccine at the beginning and 4 and 24 weeks after initiation of IFN therapy (n = 25) or recombinant IFN-alpha-2b (5 million units/m(2) subcutaneously thrice weekly) alone for 9 months (n = 25). Children were followed for at least 6 months after the end of therapy.

RESULTS

There was no statistically significant difference in the mean alanine aminotransferase levels, histologic activity index and fibrosis scores between combination and IFN monotherapy groups at the end of the therapy and end of the follow-up period. When combination and monotherapy groups were compared, the mean HBV-DNA values were significantly reduced in combination group at the end of the therapy (P = 0.004), but no statistically significant difference was found at the end of the follow up. Sustained HBeAg seroconversion with clearance of HBV-DNA was obtained in 13 of 25 children (52%) treated with combination therapy, and in eight of 25 patients (32%) treated with IFN monotherapy (P = 0.251).

CONCLUSION

Although the difference was statistically insignificant, the sustained response rates were better in the combination therapy group than in the monotherapy group. The potential benefit of combining IFN and hepatitis B vaccine should be investigated in further studies with different regimens of combination therapy.

Generation of cytotoxic T cell against HBcAg using retrovirally transduced dendritic cells

AIM: Cytotoxic T lymphocytes (CTLs) play an important role in resolving HBV infection. In the present study, we attempted to evaluate the efficiency of bone marrow-derived dendritic cells (DCs) transduced with recombinant retroviral vector bearing hepatitis B virus (HBV) core gene and the capability of generating CTLs against HBcAg by genetically modified DCs in vivo.

METHODS: A retroviral vector containing HBV core gene was constructed. Replicating DC progenitor of C57BL/6 mice was transduced by retroviral vector and continually cultured in the presence of recombinant mouse granulocyte-macrophage colony-stimulating factor (rmGM-CSF) and interleukin-4(IL-4) for 6 d. LPS was added and cultured for additional two days. The efficiency of gene transfer was determined by PCR, Western blot and FACS. Transduced DCs immunized C57BL/6 mice subcutaneously 2 times at an one-week interval. Intracellular IFN-γ and IL-4 of immunized mice lymphocytes were analyzed. Generation of CTLs in lymphocytes stimulated with mitomycin C-treated EL4-C cell which stably expresses HBcAg was determined by LDH release assays.

RESULTS: Recombinant retroviral expression vector (pLCSN) was positively detected by PCR as well as enzyme digestion with EcoRI and BamH I. Retroviruses were generated by pLCSN transfection packing cell and the virus titer was 3 × 10⁵ CFU/ml. Indirect immunofluorescence and FACS showed that HBV core gene was expressed in murine fibroblasts. Transduced bone marrow cells had capability of differentiating into DCs in vitro in the presence of rmGM-CSF and rmIL-4. The result of PCR showed that HBV core gene was integrated into the genome of transduced DCs. Western blot analysis showed that HBV core gene was expressed in DCs. The transduction rate was 28% determined by FACS. Retroviral transduction had no influence on DCs expressions of CD80 and MHC class II. HBcAg specific CTLs and Th1 type immune responses could be generated in the mice by using transduced DCs as antigen presenting cells (APCs).

CONCLUSION: Retroviral transduction of myeloid DCs progenitors expresses efficiently HBcAg, and genetically modified DCs evoke a higher CTLs response than HBcAg in vivo.

Decreased ratio of CD4/CD8 lymphocytes might be predictive for successful interferon alpha and lamivudine combined therapy in childhood chronic hepatitis B infection: A preliminary study

BACKGROUND

In the development of chronic hepatitis with hepatitis B virus infection and in response to therapy, the immune status of the infected host plays a critical role. In this study, immunological variables were assessed in patients before interferon alpha and lamivudine therapy to determine if any pretreatment immunological parameter could be an indicator of response to therapy in childhood chronic hepatitis B infection.

METHODS

Forty-four patients with chronic hepatitis B virus infection, aged 9.0 +/- 3.9 years, were enrolled in the study. The pretreatment clinical features, biochemical test results, histological activity indexes and immunological parameters were evaluated. All patients received interferon alpha for 6 months and lamivudine for 52 weeks. Four patients who could not be followed up were excluded from the study. The other 40 patients have been followed for a mean period of 27.5 +/- 9.7 months after therapy discontinuation.

RESULTS

Seventeen patients showed loss of hepatitis B early antigen (HBeAg) with appearance of anti-HBe (42.5%) and six of those who responded also showed loss of hepatitis B surface antigen (HBsAg) with the presence of anti-HBs (15%). Except elevated aspartate aminotransferase levels, there was no significantly correlation between response and sex, age, pretreatment duration of disease and histological activity indexes. Pretreatment immunoglobulins (Ig), IgG subclasses, complement C3, C4 and secretory IgA levels were also not found to be significantly related to response. The evaluation of lymphocyte subsets showed that therapy responders had significantly reduced pretreatment ratios of CD4/CD8+ lymphocytes due to prominent increased percentages of CD8+ cells. The other cellular immunity parameters and some cell surface adhesion molecules were similar in both groups.

CONCLUSION

This study emphasizes the importance of increased pretreatment CD8+ lymphocyte percentages leading to a significant decrease in CD4/CD8 ratio in chronic hepatitis B virus infection of childhood as an immunological factor predicting response to treatment.

Boosting immunity by antiviral drug therapy: a simple relationship among timing, efficacy, and success

Drug therapies against persistent human infections such as hepatitis C virus, hepatitis B virus, and HIV fail to consistently eradicate the infection from the host. Hence, recent emphasis has shifted to the study of antiviral therapy aimed at boosting specific immune responses. It was argued that structured therapy interruptions were required to achieve this, because such regimes have shown promising results in early HIV infection. Using mathematical models, we show that, contrary to this notion, a single phase of drug therapy can result in the establishment of sustained immunity. We present a simple relationship between timing of therapy and efficacy of the drugs required for success. In the presence of strong viral suppression, we show that therapy should be stopped relatively early, and that a longer duration of treatment leads to failure. On the other hand, in the presence of weaker viral suppression, stopping treatment too early is detrimental, and therapy has to be continued beyond a time threshold. We discuss our modeling results primarily in the context of HCV therapy during chronic infection. Although the therapy regimes explored here also have implications for HIV, virus-mediated destruction of specific immune cells renders success unlikely during the chronic phase of the infection.

Hepatitis B treatment: rational combination chemotherapy based on viral kinetic and animal model studies

Hepatitis B virus (HBV) causes a generally non-cytopathic infection in the liver. Even though HBV is a DNA virus, it replicates via reverse transcription which is coordinated within the viral nucleocapsid by the virus-specific polymerase. The major transcriptional template is the viral mimichromosome from which the viral DNA exists as a covalently closed circular (ccc) molcule. The virus infects hepatocytes but can also be found in non-hepatocyte reservoirs such as bile-duct epithelium, mesangial cells of the kidney, pancreatic islet cells and lymphoid cells. When patients infected with HBV are treated with either interferon alpha or lamivudine, responses are variable and unpredictable. Sophisticated mathematical models analysing the dynamics of viral clearance during antiviral therapy have recently been applied to chronic hepatitis B. Typically complex profiles, rather than the usual biphasic responses seen with other diseases have been observed, indicating that antiviral efficacy requires substantila improvement. This may be achieved with combination chemotherapy. However, chronic hepatitis B is a complex and heterogeneous disease entity, and the challenge for the future is to define measurable end-points of treatment and address key virological issues such as the role of cccDNA and extra-hepatocyte replication in treatment failure. Clearly, new therapies and effective combination therapy protocols are urgently required in order to improve the present poor response rates in patients undergoing treatment.

Hepatitis B virus reactivation with clinical flare in allogeneic stem cell transplants with chronic graft-versus-host disease

We conducted a retrospective study with the aim of identifying risk factors and clinical characteristics associated with HBV reactivation and clinical flare after allogeneic stem cell transplantation (aSCT). We reviewed the King Faisal Specialist Hospital and Research Center International Bone Marrow Transplant Registry database from January 1998 to June 2000. Complete serological screening for HBV was available in 128 of 131 patients transplanted during that period. Fifty-four (42%) had evidence of prior infection and recovery from HBV before transplant (hepatitis B core antibody positive, B surface antigen negative). Forty-two were evaluable for HBV reactivation and clinical flare. Six (14%) reactivated with clinical flare as documented by seroconversion and/or positive HBV DNA in the serum with biochemical hepatitis at 5.5, 18, 18, 19, 21 and 23 months post-transplant. Five of fifteen patients with chronic graft-versus-host disease (cGVHD) reactivated with clinical flare in contrast to 1/27 without cGVHD (RR: 9.0, 95% CI: 1.2-70.1 P < 0.02). HBV reactivation with clinical flare occurred during immunosuppressive therapy tapering or withdrawal in all patients. In conclusion, hepatitis B core antibody positive allogeneic stem cell recipients with cGVHD are at significant risk of HBV reactivation with clinical flare.

Control or persistence of hepatitis B virus: the critical role of initial host-virus interactions

Following infection with hepatitis B virus (HBV), the period before symptomatic disease is now recognized as a time of dynamic interaction between virus and host. Recent work has shown that this period is the phase of infection during which maximal changes in virus replication and the activation of critical components of the immune system occurs. This suggests that the different outcomes following exposure might be determined during the early phase of infection, before the onset of clinical disease. The hypothesis that small differences in the dynamic relationship between host and virus, such as in the kinetics of HBV replication, may influence the final outcome of infection, will be discussed.