A pilot randomized controlled trial of dual-plasmid HBV DNA vaccine mediated by in vivo electroporation in chronic hepatitis B patients under lamivudine chemotherapy

A DNA vaccine against the hepatitis B virus (HBV), enhanced by IL-2/IFN-γ fusion protein expression from a plasmid construct and mediated by in vivo electroporation, was evaluated in a total of 39 HBeAg-positive patients with chronic hepatitis B (CHB). The six of 39 patients with a serum alanine aminotransferase (ALT) value of 1-2 times upper limit of normal (ULN) were assigned to the open-label arm (Group01) receiving vaccine monotherapy; the remaining 33 patients with an ALT of more than two times ULN were enroled to the randomized and controlled arm (Group02) receiving lamivudine (LAM) monotherapy (LAM+placebo) or combined therapy (LAM+DNA vaccine) in 1:2 ratio. In Group01, a significant elevation of HBV-specific IFN-γ-secreting T-cell counts in comparison with baseline was observed. In Group02, the proportion of patients with HBV DNA suppression was higher with LAM+DNA vaccine than with LAM monotherapy at each visit time point after the final injection of DNA vaccine at week 36, revealing a significant difference between the two groups (P = 0.03) at week 60. The incidence of dual-site mutations of rtM204/I/S+rtL180M was significantly lower (P = 0.03) with an identified lower virological breakthrough (VBT) rate (P = 0.03) in patients receiving LAM+DNA vaccine than LAM monotherapy, accompanied with a significant higher positive T-cell response rate in patients receiving LAM+DNA vaccine (P = 0.03). In conclusion, this study provides evidence that HBV DNA vaccination is safe and immunologically effective, and that the HBV-specific T-cell responses induced by DNA vaccination under LAM chemotherapy showed a correlation with the suppression of viral replication in patients with CHB.     

Specific vaccine therapy in chronic hepatitis B: induction of T cell proliferative responses specific for envelope antigens.

In a pilot study, it was established that specific therapy by standard anti-hepatitis B virus (HBV) vaccination may be effective in reducing HBV replication and canceling the immune tolerance to hepatitis B surface antigen (HBsAg) particles in about 50% of persons with chronic active HBV replication. In the present study, the vaccine-induced immune responses were analyzed during an ongoing controlled multicenter vaccine trial. Vaccination elicited peripheral blood mononuclear cell proliferative responses specific for envelope antigen in 7 of 27 subjects given HBsAg. The responses induced by the vaccines were mediated by CD4+ T lymphocytes, and at least three different epitopes were recognized. HBV-specific CD4+ T lymphocytes produced high levels of interferon-gamma [corrected] and belonged to a T helper 1 subset. Reduction of serum HBV DNA in some of these persons suggests that induction of CD4+ T cell responses could be important in controlling viremia during vaccine therapy of chronic HBV carriers.     

Immune therapy including dendritic cell based therapy in chronic hepatitis B virus infection

Hepatitis B virus (HBV) infection is a global public health problem. Of the approximately 2 billion people who have been infected worldwide, more than 400 million are chronic carriers of HBV. Considerable numbers of chronic HBV carriers suffer from progressive liver diseases. In addition, all HBV carriers are permanent source of this virus. There is no curative therapy for chronic HBV carriers. Antiviral drugs are recommended for about 10% patients, however, these drugs are costly, have limited efficacy, and possess considerable side effects. Recent studies have shown that immune responses of the host to the HBV are critically involved at every stage of chronic HBV infection: (1) These influence acquisition of chronic HBV carrier state, (2) They are important in the context of liver damages, (3) Recovery from chronic HBV-related liver diseases is dependent on nature and extent of HBV-specific immune responses. However, induction of adequate levels of HBV-specific immune responses in chronic HBV carriers is difficult. During the last one decade, hepatitis B vaccine has been administered to chronic HBV carriers as a therapeutic approach (vaccine therapy). The present regimen of vaccine therapy is safe and cheap, but not so effective. A dendritic cell-based therapeutic vaccine has recently been developed for treating chronic HBV infection. In this review, we will discuss about the concept, scientific logics, strategies and techniques of development of HBVspecific immune therapies including vaccine therapy and dendritic cell-based vaccine therapy for treating chronic HBV infection.     

乙型肝炎病毒感染临床转归与宿主细胞免疫的相关性研究

目的 比较慢性乙型肝炎患者、HBV携带者、HBV既往无症状感染者之间T细胞亚群和HBV特异性CD4+ T细胞应答强度的差异,分析宿主的细胞免疫状态对HBV感染后临床转归的影响,探讨乙型肝炎的发病机制,为慢性乙型肝炎的治疗提供新的线索.方法 选取2004年2-10月在北京协和医院肝炎门诊就诊的慢性乙型肝炎患者30例、HBV携带者22例、HBV既往无症状感染者9例以及正常对照11例,使用流式细胞仪检测其T细胞亚群,使用酶联免疫斑点法检测病毒特异性CD4+T细胞应答强度,分析其差异及临床意义.结果 慢性乙型肝炎组CD4+T细胞计数显著低于HBV既往无症状感染组和正常对照组;慢性乙型肝炎组、HBV携带者组、HBV既往无症状感染组病毒特异性CD4+ T细胞应答强度分别为(156±105)、(56±68)、(229±114)SFC/106PBMC(每106个外周血单个核细胞中斑点形成细胞的个数);慢性乙型肝炎组明显高于HBV携带者组(P＜0.01),而低于HBV既往无症状感染组(P＜0.05).结论 慢性乙型肝炎患者、HBV携带者、HBV既往无症状感染者病毒特异性T细胞应答强度存在差异,这种差异可能是造成HBV感染后不同临床转归的主要因素之一.     

Hepatitis B virus-specific T-cell proliferation and cytokine secretion in chronic hepatitis B e antibody-positive patients treated with ribavirin and interferon alpha

Immune elimination of hepatitis B virus (HBV) during antiviral therapy depends on the activation of T-cell responses, which are generally impaired in chronic hepatitis B. HBV-specific T helper (Th)-cell reactivity has been assessed post-treatment in liver and peripheral blood of 18 anti-HBe-positive patients with chronic hepatitis B administered combined ribavirin/interferon alfa (IFN-alpha) therapy. The results showed that patients with undetectable HBV DNA by quantitative polymerase chain reaction under combination therapy were able to mount an HBV-specific CD4(+) Th-cell proliferative response and such T-cell reactivity is detectable 1 year after HBV DNA clearance. Hepatitis B virus core (HBcAg) and e (HBeAg) antigen-specific Th-cell proliferation was found more frequently in the liver and peripheral blood in those patients who sustained the alanine aminotransferase (ALT) normalization together with HBV DNA loss. However, HBV-specific IFN-gamma production in vitro in peripheral blood mononuclear cells augmented in 4 of 5 sustained responders and all 13 nonresponders, interleukin 10 (IL-10) production decreased in all 5 sustained responders but increased in 7 of 13 nonresponders. Furthermore, intrahepatic HBcAg plus HBeAg-specific Th-cell proliferation only occurred in sustained responders (2 of 3, 67%, vs. 0 of 9; P =.045) whose cells showed in vitro significantly increased productions in HBcAg/HBeAg-specific IFN-gamma and IL-12 compared with nonresponders in whom IFN-gamma and IL-12 productions decreased together with increased IL-10 secretion. In conclusion this study indicates that combined therapy with ribavirin and IFN-alpha for chronic hepatitis B not only significantly reduces viremia levels but also induces lasting CD4(+) T-cell proliferation and Th1 cytokine release at the site of infection, which may lead to sustained eradication of the HBV.     

Resolution of chronic hepatitis B and anti-HBs seroconversion in humans by adoptive transfer of immunity to hepatitis B core antigen

BACKGROUND & AIMS: Impaired T-cell reactivity is believed to be the dominant cause of chronic hepatitis B virus (HBV) infection. We characterized HBV-specific T-cell responses in chronic hepatitis B surface antigen carriers who received bone marrow from HLA-identical donors with natural immunity to HBV and seroconverted to antibody to hepatitis B surface antigen. METHODS: T-cell reactivity to HBV antigens and peptides was assessed in a proliferation assay, the frequency of HBV core- and surface-specific T cells was quantified directly by ELISPOT assays, and T-cell subsets were analyzed by flow cytometry. RESULTS: CD4+ T-cell reactivity to HBV core was common in bone marrow donors and the corresponding recipients after hepatitis B surface antigen clearance, whereas none reacted to surface, pre-S1, or pre-S2 antigens. Furthermore, CD4+ T cells from donor/recipient pairs recognized similar epitopes on hepatitis B core antigen; using polymerase chain reaction for the Y chromosome, the recipients' CD4+ T lymphocytes were confirmed to be of donor origin. The frequency of core-specific CD4+ and CD8+ T cells was several-fold higher than those specific for surface antigen. CONCLUSIONS: This study provides the first evidence in humans that transfer of hepatitis B core antigen-reactive T cells is associated with resolution of chronic HBV infection. Therapeutic immunization with HBV core gene or protein deserves further investigation in patients with chronic hepatitis B.     

Efficacy and limitations of a specific immunotherapy in chronic hepatitis B

BACKGROUND/AIMS: This controlled study aimed to evaluate the efficacy and potential side effects of hepatitis B virus (HBV) vaccination as active immunotherapy in HBV-related chronic hepatitis. METHODS: The 118 included patients were 'naive' subjects who had never received any previous anti-HBV therapy, showed detectable serum HBV DNA and had biopsy-proven chronic hepatitis. In a 12-month follow-up they were given either five intramuscular injections of 20 microg of a preS2/S (GenHevac B, Pasteur-Mérieux) (n = 46) or an S vaccine (Recombivax Merck & Co.) (n = 34) or no treatment as a control (n = 37). The efficacy of vaccination was evaluated by testing for serum HBV DNA negativation using a standard liquid hybridization assay. RESULTS: Three months after the first three vaccine injections, the percentage of serum HBV DNA negativation was higher in the vaccine groups (16.3%) than in the control group (2.7%) (P = 0.033, by the chi2 Pearson test) and was more frequently observed in patients who had pretreatment viremia >200 pg/ml (none in the control group vs. 16.7% in the vaccinated groups) (P = 0.025). After 12 months follow-up and five vaccine injections, there was no difference in the rate of serum HBV DNA negativation between vaccinated and unvaccinated subjects but HBV vaccines significantly decreased the HBV viral load between the sixth and twelfth months (P = 0.04) in contrast with the control group. The rate of HBe/anti-HBe seroconversion after 6 months of follow-up occurred only in eight (13.3%) vaccinated patients and in one (3.6%) of the controls. Disappearance of serum HBsAg was not observed in any of the patients. CONCLUSIONS: This controlled study offers direct evidence that the HBV vaccine may decrease HBV replication in chronic hepatitis B patients. It also emphasizes the need for reinforced immunization strategies as well as combination therapies.     

Engineering immune therapy against hepatitis B virus

Approximately 350–400 million people worldwide are chronically infected with the hepatitis B virus (HBV). These individuals harbor the virus for their whole life and they transmit the virus to uninfected individuals. In addition, considerable numbers of chronic HBV carriers develop progressive liver diseases like chronic hepatitis B, liver cirrhosis and hepatocellular carcinoma. At present, antiviral agents like type-1 interferons, lamivudine, adefovir and entacavir are used to treat a selected population of chronic HBV carriers. These antiviral treatments are not satisfactory in that they are unable to eradicate HBV, only partially efficient in less than 30% subjects, expensive, can have debilitating side-effects and require constant monitoring. In addition, once treatment is stopped, the virus and clinical conditions return in many patients. Recent advancements in cellular and molecular biology indicate that the host's immune responses to HBV play cardinal roles during acquisition, pathogenesis, progression, and complications of chronic HBV infection. Immune responses are also important in the context of antiviraltherapy and clinical recovery. This explains why the efficacy of antiviral drugs is limited even in some selected patients with chronic HBV infection. Various published work now state that HBV-specific immunity may be beneficial for patients with chronic HBV infection and non-HBV-specific immunity may be related to flare up of liver diseases. Accordingly, a new few field of immunological research and clinical application of prophylactic vaccines (vaccine therapy) has been started in chronic HBV carriers. Vaccine therapy has inspired optimism as a new therapeutic approach, but it is unlikely that the present regimen of vaccine therapy will stand the test of time. Based on present understandings about vaccine/host interactions, we provide herein an outline for engineering more potent regimen of HBV-specific immune therapy against HBV.     

The effect of recombinant hepatitis B vaccine therapy in chronic hepatitis B infection.

BACKGROUND/AIMS: Immune-modulator and antiviral treatments for carriers of hepatitis B virus are known to have poor efficacy with a high cost and frequent side effects, which has led to investigation of new treatment modalities. The aim of this study was to determine the efficacy of recombinant hepatitis B vaccine in the treatment of patients with chronic hepatitis B (HBV DNA >5 pg/ml, ALT>60) infection diagnosed histopathologically and asymptomatic carriers (HBV DNA<5 pg/ml, ALT <40, Anti Hbe positive) of the virus. METHODS: The vaccine (Gen Hevac B Pasteur) was administered at baseline and at months one and six to patients with chronic hepatitis and asymptomatic carriers. Ten cases with chronic hepatitis B infection were assigned to a control group to whom no treatment was given. Biochemical and microbiological investigations were performed at baseline and at months three, six and twelve in all cases. Seroconversion of Hbe Ag, loss of HBV DNA and normalization of ALT were considered as a positive response. RESULTS: Patients with chronic hepatitis B who were given the vaccine were found to have significantly low levels of HBV DNA at 12 months (63.2+/-20pg/ml) compared to baseline values (174.4+/-36.9pg/ml), while controls were found to have high levels of HBV DNA at 12 months (223.1+/-33pg/ml) compared to baseline values (165.2+/-33.2pg/ml) (p<0.05). At 12 months, HBV DNA had become negative in seven of 19 patients given the vaccine (36.8%) Four patients with chronic hepatitis (36.35%) were observed to have HBeAg seroconversion and one patient (5.2%) HBsAg seroconversion at the end of 12 months and there were four (21.05%) patients who responded positively to vaccine therapy in this group. Asymptomatic carriers and controls did not have seroconversion of HBs Ag. Also, HBV DNA did not become negative in controls. CONCLUSION: It may be concluded that recombinant hepatitis B vaccine is effective in the treatment of chronic hepatitis B.     

Complementary Presence of HBV Humoral and T-cell Response Provides Protective Immunity after Neonatal Immunization

Background and AimsHepatitis B vaccination is the most cost effective way to prevent hepatitis B virus (HBV) infection. Hepatitis B vaccine (HepB) efficacy is usually assessed by anti-hepatitis B surface antigen (HBsAg) level, but there are few reports of humoral and cellular immune responses to HepB in children after neonatal vaccination.MethodsA group of 100 children with a history of primary hepatitis B immunization were included in this study to evaluate the efficacy of HepB. Blood samples were obtained from 80 children before, and 41 children after, a single HepB booster dose. Children with low anti-HBsAg (HBs) titers of <100 mIU/mL received a booster dose after giving their informed consent. Anti-HBsAg, T-cell response and percentage of B-cell subsets were assayed before and after the booster.ResultsOf the 80 children, 81.36% had positive T cell and anti-HBsAg responses at baseline. After the booster dose, the anti-HBsAg titer (p<0.0001), positive HBsAg-specific T-cell response (p=0.0036), and spot-forming cells (p=0.0003) increased significantly. Compared with pre-existing anti-HBsAg titer <10 mIU/mL, the anti-HBsAg (p=0.0005) and HBsAg-specific T-cell responses (p<0.0001) increased significantly in preexisting anti-HBsAg titer between 10 and 100 mIU/mL group. Change of the HBV-specific humoral response was the reverse of the T-cell response with age. Peripheral blood lymphocytes, B cells, and subset frequency decreased.ConclusionsHBV immunization protection persisted at least 13 years after primary immunization because of the complementary presence of HBV-specific humoral antibodies and a T-cell immune response. One dose of a HepB booster induced protective anti-HBsAg and promoted an HBsAg-specific T-cell response. In HBV endemic regions, a HepB booster is recommended to children without anti-HBsAg because of effectiveness in HBV prevention.     

Cellular and humoral immune responses induced by intradermal or intramuscular vaccination with the major hepatitis B surface antigen

The vaccination route may influence the success of immunization against pathogens. The conventional intramuscular (i.m.) application of a vaccine containing the hepatitis B virus (HBV) surface antigen (HBsAg) led to protective anti-HBs antibody levels in the majority of vaccine recipients. In this study, we vaccinated healthy volunteers and a group of i.m. vaccine nonresponders via the intradermal (i.d.) route and analyzed the HBV-specific B-cell response as well as class-II- and class-I-restricted T-cell responses by (3)H-thymidine uptake, enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISPOT). The results were then compared with i.m. vaccinated controls. I.d. vaccinations were well tolerated and induced neutralizing anti-HBs antibodies in all naive vaccine recipients and, importantly, all but one former i.m. nonresponder developed protective anti-HBs serum antibody levels after 2 or 3 i.d. immunizations. On the cellular level, i.d. vaccine recipients showed significantly higher anti-HBs producing B-cell frequencies and more vigorous class-II-restricted T-helper (Th) cell responses than i.m. controls. However, although the HBsAg-specific T cells were characterized by their cytokine release as Th1-like cells in both groups, human leukocyte antigen (HLA)-A2+ individuals who received the soluble HBsAg via the i.d. route developed higher peptide-specific cytotoxic CD8+ T cell precursor (CTLp) frequencies. In conclusion, i.d. HBsAg vaccination is more effective even in former i.m. vaccine nonresponders with respect to antibody induction and specific B- and T-cell responses. The induction of virus-specific CTLp may provide the rationale to study the i.d. HBsAg vaccine in the treatment of chronic hepatitis B.     

Ribavirin and IFN-α combination therapy induces CD4+ T-cell proliferation and Th1 cytokine secretion in patients with chronic hepatitis B

AIM: To investigate the anti-viral mechanism of combination therapy of interferon (IFN)-α and ribavirin in patients with chronic hepatitis B.METHODS: Twenty patients were assigned to receive either IFN-α plus ribavirin (group A,n = 14) or no treatment as a control (group B,n = 6). Patients were analyzed for T-cell proliferative responses specific for hepatitis B virus (HBV)-antigen and cytokine production by peripheral blood mononuclear cells (PBMCs).RESULTS: Combination therapy induced HBV-antigen specific CD4+ T-cell proliferative responses in four patients (28.6%). Production of high levels of HBV-specific IFN-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-12 by PBMCs was found in five patients (35.7%),who showed significantly lower HBV DNA levels in serum at 12 mo after treatment ended (P = 0.038) and at 24 mo of follow-up (P = 0.004) than those without high levels of cytokine production.CONCLUSION: HBV-antigen specific CD4+ T cells may directly control HBV replication and secretion of anti-viral T helper 1 (Th1) cytokines by PBMCs during combination therapy of chronic hepatitis B with ribavirin and IFN-α.     

Ribavirin and IFN-α combination therapy induces CD4＋ T-cell proliferation and Thl cytokine secretion in patients with chronic hepatitis B

AIM： To investigate the anti-viral mechanism of combination therapy of interferon （IFN）-α and ribavirin in patients with chronic hepatitis B.
METHODS： Twenty patients were assigned to receive either IFN-α plus ribavirin （group A, n = 14） or no treatment as a control （group B, n = 6）. Patients were analyzed for T-cell proliferative responses specific for hepatitis B virus （HBV）-antigen and cytokine production by peripheral blood mononuclear cells （PBMCs）.
RESULTS： Combination therapy induced HBV-antigen specific CD4＋ T-cell proliferative responses in four patients （28.6%）. Production of high levels of HBV- specific IFN-γ, tumor necrosis factor （TNF）-α, interleukin （IL）-12 by PBMCs was found in five patients （35.7%）, who showed significantly lower HBV DNA levels in serum at 12 mo after treatment ended （P = 0.038） and at 24 mo of follow-up （P = 0.004） than those without high levels of cytokine production.
CONCLUSION： HBV-antigen specific CD4＋ T cells may directly control HBV replication and secretion of anti-viral T helper 1 （Th1） cytokines by PBMCs during combination therapy of chronic hepatitis B with ribavirin and IFN-α.     

A pilot study of the CY-1899 T-cell vaccine in subjects chronically infected with hepatitis B virus. The CY1899 T Cell Vaccine Study Group.

Clinical observations suggest that eradication of the hepatitis B virus (HBV) is immune-mediated. Vigorous cytotoxic T lymphocyte (CTL) activity directed at HLA class I-bound viral epitopes are detected during acute hepatitis B, but not in chronic hepatitis B carriers. A CTL epitope derived from the hepatitis B core protein amino acids 18-27 has been incorporated into a vaccine also comprised of a T-helper cell epitope and 2 palmitic acid residues (CY-1899). The aim of this study was to determine whether repeated doses of CY-1899 given to patients with chronic hepatitis B could initiate in vivo CTL activity and viral clearance. Patients with chronic hepatitis B received up to 4 doses (ranging from 0.05 mg to 15 mg) 6 weeks apart. Following vaccination, patients were monitored for hepatitis B surface antigen and "e" status, HBV-DNA levels, liver biochemistry, CTL activity, and any adverse events. Ninety patients with chronic hepatitis B infection received CY-1899. Mean CTL responses were all low but were maximal following vaccination with 5 mg CY-1899. Peak CTL responses never exceeded 10 lytic units (LU) regardless of vaccine dose, this value being well below that seen following resolution of acute hepatitis B. No significant changes in liver biochemistry or viral serology were observed during follow-up. No serious adverse events were noted. Administration of the single-epitope vaccine, CY-1899, initiated CTL activity, but of a magnitude lower than that observed during spontaneous HBV clearance. This low-level CTL activity was not associated with viral clearance.     

Suppression of hepatitis B virus replication mediated by hepatitis A-induced cytokine production

BACKGROUND: Acute hepatitis A virus (HAV) infection can cause severe hepatitis especially in patients with underlying chronic liver disease. In patients with pre-existing chronic hepatitis B (HBV) acute HAV infection can suppress HBV replication. The exact mechanism of HBV suppression during acute HAV infection is still a subject of debate. One mechanism may be the production of HAV infection-induced cytokines leading to suppression of HBV replication and viral clearance. AIM: To evaluate cytokine production and HBV-specific lympho-proliferative responses (LPR) during acute HAV infection in a patient with chronic HBV infection-clearing markers of active HBV replication. DESIGN: Early detection of a case of acute HAV infection in an HBeAg-positive, HBV DNA-positive chronic HBV patient treated with lamivudine. RESULTS: At the time of HAV infection a sharp peak in the gamma-interferon (IFN-gamma) level occurred just before the rise in serum transaminase activity. This was subsequently followed by a decrease in HBV DNA and HBeAg below the limit of detection of the assay. However the HBV-specific T-cell response was not modified. After resolution of the acute HAV infection and withdrawal of antiviral therapy HBV replication relapsed. CONCLUSION: The sharp rise in IFN-gamma production mediated by the acute HAV infection may be pivotal in the suppression of HBV replication in chronic hepatitis B.     

Reduced hepatitis B virus surface antigen-specific Th1 helper cell frequency of chronic HBV carriers is associated with a failure to produce antigen-specific antibodies in the trimera mouse

In chronic hepatitis B virus (HBV) infection weak antiviral immune responses are associated with viral persistence. We studied possible immune deficits underlying the lack of serum antibodies of such patients against the HBV surface antigen (HBsAg) in a novel human/mouse chimeric model. A hepatitis B surface antigen (HBs) vaccination of Balb/c mice engrafted with peripheral blood mononuclear cells (PBMC) of naturally HBV-immunized donors induced high frequencies of human HBsAg-specific B and T helper 1 (Th1) cells. These responses were associated with high serum anti-HBs antibody levels of the subclasses immunoglobulin G1 (IgG1) and IgG2 that are driven by interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). In contrast, PBMC of chronic HBV carriers transplanted into the chimera failed to produce anti-HBs antibodies after vaccination with HBsAg and exhibited a deficit of antigen-specific Th1 cells. A possible influence of HBsAg or viremia was excluded by the lack of viral replication in such chimera. The observed T-cell defect was specific for HBsAg, as the B- and T-cell responses to tetanus toxoid (TT) were fully retained. Thus, our study shows that viral persistence in chronic HBV carriers is associated with an HBsAg-specific Th1 cell defect, which likely is responsible for the insufficient neutralizing anti-HBs-antibody response and is not reversed by HBs vaccination. Alternative approaches to induce HBs-specific Th1 cell responses might represent a future therapeutic option.     

Therapeutic vaccination in chronic hepatitis B: preclinical studies in the woodchuck model

Summary.  Interferon-α and nucleoside analogues are available for the treatment of chronic hepatitis B virus (HBV) infection but do not lead to a satisfactory result. New findings about the immunological control of HBV during acute infection suggest the pivotal role of T-cell mediated immune responses. Several preclinical and clinical trials were undertaken to explore the possibility of stimulating specific immune responses in chronically infected animals and patients by vaccination. However, vaccination with commercially available HBV vaccines in patients and immunization in woodchucks with core or surface proteins of woodchuck hepatitis virus (WHV) did not result in effective control of HBV and WHV infection, suggesting that new formulations of therapeutic vaccines are needed. Some new approaches combining antiviral treatments with nucleoside analogues, DNA vaccines and protein vaccines were tested in the woodchuck model. It could be shown that therapeutic vaccinations are able to stimulate specific B- and T-cell responses and to achieve transient suppression of viral replication. These results suggest the great potential of therapeutic vaccination in combination with antivirals to reach an effective and sustained control of HBV infection.     

The impact of HBV-DNA fluctuations on virus-specific CD8+ T cells in HBeAg+ chronic hepatitis B patients treated with a steroid and lamivudine

Restoration of anti-viral immune response may be a requisite for sustained virological response to treatment in chronic hepatitis B patients. Over a 13-month period, we examined the dynamics of hepatitis B virus (HBV)-specific CD8+ cells in six human leucocyte antigen (HLA)-A2+ hepatitis B e antigen (HBeAg)+ 'immunotolerant' chronic hepatitis B patients treated sequentially with corticosteroid and lamivudine. Our results show that the combination treatment did not result in a sustained restoration of anti-viral specific CD8+ cells in five of the six patients studied. However, HBV-specific CD8+ cells, despite being severely compromised, were not totally deleted. Paradoxically, steroid treatment was not associated with inhibition but with a minimal increase of the HBV-specific CD8 response, and we observed that nucleocapsid-specific CD8 responses were not rescued by stable and prolonged inhibition but became detectable after rapid rebounds of HBV replication. In most patients, the transient and minimal restoration of HBV-specific immunity was not associated with clinical benefits. Our results describe a dynamic relationship between HBV-specific CD8+ cells and HBV-DNA values, that could potentially be used for a better design of HBV treatment in HBeAg+ 'immunotolerant' chronic hepatitis B patients.     

The lack of effect of therapeutic vaccination with a pre-S2/S HBV vaccine in the immune tolerant phase of chronic HBV infection

BACKGROUND/AIMS: Even if the results are controversial and preliminary, several reports suggest that the HBV vaccine might be effective in treating HBV infection. In this study, we aimed to evaluate the efficacy and safety of specific anti-HBV vaccination for the immune tolerance phase of chronic HBV infection in a randomized, controlled study. PATIENTS AND METHODS: The 47 subjects included patients that were treatment-naive with hepatitis B e antigen positivity, active hepatitis B virus replication as measured by hepatitis B virus DNA levels, persistently normal alanine transaminase levels, and with minimal or absent disease activity by liver biopsy. Thirty patients were given three intramuscular injections of 20 micro g of a pre-S2/S vaccine (GenHevac-B) on days 0, 30, and 60, and the remaining 17 patients were included in the control group. The efficacy of vaccination was evaluated by testing for loss of serum HBV DNA or decrease in its level and for HBeAg seroconversion. A significant decrease in HBV DNA levels was accepted as a decrease of >50% of initial values. The complete response was defined as loss of HBV DNA in serum with HBeAg seroconversion. Postvaccination follow-up lasted 12 months after the first dose. RESULTS: No significant effects were observed in the vaccination population in the reduction of HBV DNA to undetectable levels, or to <50% of prevaccination levels, in HBeAg/anti-HBe seroconversion, or in transaminase levels. There was an early clearance/decrease in HBV DNA levels in five vaccinated patients by 3 months, and none in controls (P = 0.143), and two of them had sustained responses later. At the end of follow-up, complete response is almost similar in study as well as control group (13% vs. 12%, P > 0.05). Disappearance of serum HBV DNA was more frequently observed in those patients who had pretreatment viremia of <100 pg/mL in both groups. The median levels of HBV DNA and alanine transaminase activity between baseline and 12 months did not differ significantly in both groups. All patients remained HBsAg positive and none developed anti-HBs. No serious adverse event was encountered in vaccinated patients, and the therapy was well tolerated. Follow-up lasted a median of 16 months (range 12-30 months) for the study group and 18 months (range 12-31months) for the control group. CONCLUSIONS: Immunotherapy with specific anti-HBV vaccine in the immune tolerance phase of chronic HBV infection did not offer additional benefit. New immunotherapeutic strategies to control HBV infection by specific HBV vaccines in chronically infected subjects are needed.     

Transfer of HBV genomes using low doses of adenovirus vectors leads to persistent infection in immune competent mice

Studies of mechanisms responsible for the persistence of hepatitis B virus (HBV) infection have been hindered by a lack of appropriate animal models. HBV genomes can be delivered to livers of mice using hydrodynamic injection or high doses of an adenoviral vector; these lead to clearance of HBV. We found that infection of immunocompetent mice with low doses of an adenoviral vector resulted in persistent HBV infection; the mice neither underwent seroconversion to production of antibodies against HBV nor developed a strong HBV-specific effector T-cell response. As in patients with chronic HBV infection, DNA vaccination failed to generate T cells that cleared infection. This model of persistent HBV infection could be used to study the pathogenesis of chronic HBV infection and develop new therapeutic strategies.