Induction of a robust T- and B-cell immune response in non- and low-responders to conventional vaccination against hepatitis B by using a third generation PreS/S vaccine

Contriving a novel of CHB therapeutic vaccine based on IgV_CTLA-4 and L protein via immunoinformatics approach

Chronic infection induced by immune tolerance to hepatitis B virus (HBV) is one of the most common causes of hepatic cirrhosis and hepatoma. Fortunately, the application of therapeutic vaccine can not only reverse HBV-tolerance, but also serve a potentially effective therapeutic strategy for treating chronic hepatitis B (CHB). However, the clinical effect of the currently developed CHB therapeutic vaccine is not optimistic due to the weak immunogenicity. Given that the human leukocyte antigen CTLA-4 owns strong binding ability to the surface B7 molecules (CD80 and CD86) of antigen presenting cell (APCs), the immunoglobulin variable region of CTLA-4 (IgV_CTLA-4) was fused with the L protein of HBV to contrive a novel therapeutic vaccine (V_C4HBL) for CHB in this study. We found that the addition of IgV_CTLA-4 did not interfere with the formation of L protein T cell and B cell epitopes after analysis by means of immunoinformatics approaches. Meanwhile, we also found that the IgV_CTLA-4 had strong binding force to B7 molecules through molecular docking and molecular dynamics (MD) simulation. Notably, our vaccine V_C4HBL showed good immunogenicity and antigenicity by in vitro and in vivo experiments. Therefore, the V_C4HBL is promising to again effectively activate the cellular and humoral immunity of CHB patients, and provides a potentially effective therapeutic strategy for the treatment of CHB in the future.Communicated by Ramaswamy H. Sarma.

Longterm Outcome of Therapeutic Vaccination with a Third Generation Pre-S/S HBV Vaccine (PreHevbrioR) of Chronically HBV Infected Patients

Several antiviral treatment regimens for chronic hepatitis B (CHB) virus infection have been shown to be effective in suppressing viral load and reducing the risk of hepatocellular injury and its complications. It has been hypothesized that high levels of circulating HBV surface antigen(s) may lead to immune tolerance against HBV and contribute to chronic carriership. Conversely, low-level HBsAg may create a window for the reconstitution of an HBV-specific immune response through vaccination and control of infection. Previous studies in non-responders to yeast-derived HBV vaccines, using a third-generation pre-S/S vaccine, have led to up to 95% anti-HBs seroconversion. This report evaluates the long-term outcome after experimental vaccination with a pre-S/S HBV vaccine intended as a therapeutic intervention in chronic HBV carriers. Four low-level HBsAg carriers (<500 IU/mL) were vaccinated three to seven times with 20 μg PreHevbrioR. Three out of four carriers eliminated HBsAg completely and seroconverted to anti-HBs. One patient seroconverted to anti-HBs but remained with a borderline HBsAg titer (10 IU/mL). Serum anti-HBs levels following repeated vaccination varied between 27 and >1000 IU/L, respectively. Long-term observation (>6 years) showed that after discontinuing NUC treatment for at least two years, HBsAg and HBV DNA remained negative with anti-HBs positive titers ranging between 80 and >1000 IU/L. Based on our preliminary observations, there is a rationale to further evaluate the role of this vaccine as a therapeutic agent.

Oncoviruses: How do they hijack their host and current treatment regimes

Viruses have the ability to modulate the cellular machinery of their host to ensure their survival. While humans encounter numerous viruses daily, only a select few can lead to disease progression. Some of these viruses can amplify cancer-related traits, particularly when coupled with factors like immunosuppression and co-carcinogens. The global burden of cancer development resulting from viral infections is approximately 12%, and it arises as an unfortunate consequence of persistent infections that cause chronic inflammation, genomic instability from viral genome integration, and dysregulation of tumor suppressor genes and host oncogenes involved in normal cell growth. This review provides an in-depth discussion of oncoviruses and their strategies for hijacking the host's cellular machinery to induce cancer. It delves into how viral oncogenes drive tumorigenesis by targeting key cell signaling pathways. Additionally, the review discusses current therapeutic approaches that have been approved or are undergoing clinical trials to combat malignancies induced by oncoviruses. Understanding the intricate interactions between viruses and host cells can lead to the development of more effective treatments for virus-induced cancers.

PreS1 Containing HBc VLPs for the Development of a Combined Therapeutic/Prophylactic Hepatitis B Vaccine

The available HBV vaccines based on the HBV surface protein are manufactured in yeasts and demonstrate excellent prophylactic but no therapeutic activity and are thus ineffective against chronic HBV infection. Five different HBV core proteins (HBc)-full length and C-terminally truncated-were used for the insertion of the short, preS1,aa 20-47 and long, preS1phil, aa 12-60 + 89-119 fragments. Modified virus-like particles (VLPs) were compared for their biotechnological and immunological properties. The expression level of HBc-preS1 proteins was high for all investigated proteins, allowing us to obtain 10-20 mg of purified VLPs from a gram of biomass with the combination of gel filtration and ion-exchange chromatography to reach approximately 90% purity of target proteins. The immunogenicity of chimeric VLPs was tested in BALB/c mice, showing a high anti-preS1 response and substantial T-cell proliferation after stimulation with HBc protein. Targeted incorporation of oligonucleotide ODN 1668 in modified HBc-preS1 VLPs was demonstrated.

Impaired anti-HBV vaccine response in non-cirrhotic chronic HCV is not overcome by double dose regimen: randomized control trial

INTRODUCTION AND OBJECTIVES

Some studies suggest chronic HCV infection diminishes responses to the anti-HBV vaccine. We evaluated the efficacy of double versus standard dose HBV vaccination among HCV patients without cirrhosis.

PATIENTS AND METHODS

141 adults with untreated chronic HCV were randomized to HBV vaccination with double dose (40μg) or standard dose (20μg) at 0, 1 and 6 months; 70 healthy HCV-negative patients given standard dose served as controls. Vaccine response was defined by anti-HBs ≥10 mIU/mL.

RESULTS

128 patients (60 double, 68 standard doses) completed the study. Patients were of median age 52 years, 61% female, 60% fibrosis <2 of 4, and 76% genotype 1 with median 6-log _{10 IU}/mL HCV RNA. Overall seroprotection rate was 76.7% (95% CI: 65-87) in the 40μg versus 73.5% (95% CI: 63-84) in the 20μg dose HCV-positive groups (p =0.68) and 91.2% (95%CI:84-99) in HCV-negative controls (p =0.011 and 0.003, respectively). In multivariate logistic regression, vaccine dose (double vs. standard dose) was not associated with vaccine response (OR=0.63, p =0.33). Of 32 HCV-infected patients who were non-responders to 3- doses, 25 received the fourth dose of vaccine. The fourth dose seroconversion rate for the 40μg and 20μg groups were 45.5% and 21.4%, respectively.

CONCLUSIONS

In HCV-infected patients without cirrhosis, impaired responses to HBV vaccination cannot be overcome by the use of double dose HBV vaccination, but adding a fourth dose of vaccine for non-responders may be an effective strategy. Other adjuvant measures are needed to enhance seroconversion rates in these patients.

TRIAL REGISTER

U 1111-1264-2343 (www.ensaiosclinicos.gov.br).

Insights into induction of the immune response by the hepatitis B vaccine

After more than four decades of hepatitis B virus (HBV) vaccine implementation, its safety and efficacy in preventing HBV infection have been proven and several milestones have been achieved. Most countries have included HBV immunization schedules in their health policies and progress has been made regarding universalization of the first HBV vaccine dose at birth. All of these actions have significantly contributed to reducing both the incidence of HBV infection and its related complications. However, there are still many drawbacks to overcome. The main concerns are the deficient coverage rate of the dose at birth and the large adult population that has not been reached timely by universal immunization. Additionally, the current most widely used second-generation vaccines do not induce protective immunity in 5% to 10% of the population, particularly in people over 40-years-old, obese (body mass index > 25 kg/m²), heavy smokers, and patients undergoing dialysis or infection with human immunodeficiency virus. Recently developed and approved novel vaccine formulations using more potent adjuvants or multiple antigens have shown better performance, particularly in difficult settings. These advances re-launch the expectations of achieving the World Health Organization’s objective of completing hepatitis control by 2030.

Longitudinal mapping of hepatitis B vaccine-induced B-cell linear epitopes in healthy individuals

The elimination of hepatitis B virus (HBV) infection is partially facilitated by the prophylactic HB vaccine. As the loss of seroprotection over time remains a conundrum for long-lasting protection, a comprehensive dynamic analysis of immunogenic targets of the HB vaccine will provide novel insights into the improvement and design of potential targets. In this study, 36 healthy subjects without prior history of hepatitis B infection and negative for hepatitis B surface antibody (anti-HBs) were enrolled. Participants were given a series of three doses of HB vaccine on a 0-, 1-, and 6-month schedule and longitudinally followed up. We systematically mapped 55 overlapping 15-mer peptides covering the small S protein of hepatitis B virus (SHBs) of vaccinees' serum samples at seven time points by performing an ELISA assay. Additionally, the frequencies and function dynamics of adaptive immune response were assessed by flow cytometry. We found that the SHBs peptide coverage presented an overall upward trend along with the vaccination progress, and the individual subpartition recognition was strongly correlated with the anti-HBs titers. Moreover, we identified one dominant epitope (S29) located on "a determinant region" associated with effective vaccine response. Besides, significant correlations between the proportion of plasmablasts and proliferating B cells and levels of anti-HBs were ascertained. Taken together, our data characterized the dynamics of HB vaccine-induced neutralizing antibodies against B-cell linear epitopes on SHBs and adaptive immune response, which will be constructive to develop the next-generation vaccine.

Lower frequency of T stem cell memory (TSCM) cells in hepatitis B vaccine nonresponders

Despite the availability of an effective vaccine and antiviral treatments, hepatitis B is still a global public health problem. Hepatitis B vaccination can prevent the disease. Vaccination induces long-lasting protective immune memory, and the identification of memory cell subsets can indicate the effectiveness of vaccines. Here, we compared the frequency of CD4⁺ memory T cell subsets between responders and nonresponders to HB vaccination. Besides, the frequency of IFN-γ⁺ memory T cells was compared between studied groups. Study participants were grouped according to their anti-HBsAb titer. For restimulation of CD4⁺ memory T cells, peripheral blood mononuclear cells (PBMCs) were cultured in the presence of HBsAg and PHA for 48 h. Besides, PMA, ionomycin, and brefeldin were added during the last 5 h of incubation to induce IFN-γ production. Flow cytometry was used for analysis. There was a statistically significant difference in the frequency of CD4⁺CD95⁺, CD4⁺CD95^Hi, and CD4⁺CD95^low/med T stem cell memory (T_SCM) cells between responder and nonresponder groups. However, the comparison of the frequency of memory T cells producing IFN-γ showed no differences. Our results identified a possible defect of immunological CD4⁺ memory T cell formation in nonresponders due to their lower frequency of CD4⁺ T_SCM cells.

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

Background

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

Method

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

Results

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

Conclusion

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

Kidney transplant from donors with hepatitis B: A challenging treatment option

Utilizing kidneys from donors with hepatitis B is one way to alleviate the current organ shortage situation. However, the risk of hepatitis B virus (HBV) transmission remains a challenge that undermines the chance of organs being used. This is particularly true with hepatitis B surface antigen (HBsAg) positive donors despite the comparable long-term outcomes when compared with standard donors. To reduce the risk of HBV transmission, a comprehensive approach is needed. This includes assessment of donor risk, optimal allocation to the proper recipient, appropriate immunosuppressive regimen, optimizing the prophylactic therapy, and post-transplant monitoring. This review provides an overview of current evidence of kidney transplants from donors with HBsAg positivity and outlines the challenge of this treatment. The topics include donor risk assessment by adopting the nucleic acid test coupled with HBV DNA as the HBV screening, optimal recipient selection, importance of hepatitis B immunity, role of nucleos(t)ide analogues, and hepatitis B immunoglobulin. A summary of reported long-term outcomes after kidney transplantation and proposed criteria to utilize kidneys from this group of donors was also defined and discussed.

Factors influencing the durability of hepatitis B vaccine responses

The World Health Organization recommends the implementation of universal hepatitis B (HB) vaccination, and global coverage for this vaccine reached 84% in 2015. In Japan, the policy aimed at preventing mother-to-child transmission of HB virus (HBV) initially commenced as a specific vaccination program for infants born to mothers who were positive for HB surface antigen. In 2016, universal HB vaccination was implemented in this country to cover unvaccinated individuals at risk of horizontal HBV transmission. Although HB vaccination has been shown to be highly efficacious and safe, the issues of vaccine non-responders and of the loss of antibodies directed against HB surface antigen (anti-HBs) in HB vaccine recipients remain. To gain better insight into these problems, we previously performed an immunological analysis on adult vaccine recipients after they received an initial HB vaccination. We found that the course of successful HB vaccination is composed of the following distinct phases: 1) acquisition of anti-HBs antibody, 2) attainment of high anti-HBs antibody titers, and 3) maintenance of acquired anti-HBs antibody levels. In this review, we describe the significance of HB vaccination and suggest a potential means of improving the impact of HB vaccination based on our immunological analysis.

Immunogenicity and safety of a tri-antigenic versus a mono-antigenic hepatitis B vaccine in adults (PROTECT): a randomised, double-blind, phase 3 trial

BACKGROUND

The seroprotection rate (SPR) of hepatitis B vaccination in adults is suboptimal. The aim of this study was to compare the SPR of a tri-antigenic hepatitis B vaccine (TAV), with a mono-antigenic vaccine (MAV) in adults of all ages.

METHODS

This was a multicentre, double-blind, phase 3, randomised controlled trial (PROTECT) comparing the immunogenicity and safety of TAV with MAV in 28 community and hospital sites in the USA, Finland, Canada, and Belgium. Adults (aged ≥18 years) seronegative for hepatitis B virus (HBV), including those with well-controlled common chronic conditions, were randomly assigned (1:1) and stratified by study centre and age according to a web-based permuted blocked randomisation. Participants received either TAV or MAV which were administered as an intramuscular dose (1 mL) of TAV (10 μg; Sci-B-Vac, VBI Vaccines [SciVac, Rehovot, Israel]) or MAV (20 μg; Engerix-B [GlaxoSmithKline Biologicals, Rixensart, Belgium]) on days 0, 28, and 168 with six study visits and 24 weeks of follow-up after the third vaccination. Participants, investigators, and those assessing outcomes were masked to group assignment. The co-primary outcomes were to show non-inferiority of the SPRs 4 weeks after the third vaccination with TAV versus MAV in adults aged 18 years and older, as well as superiority in adults aged 45 years and older. SPR was defined as the percentage of participants attaining anti-HBs titres of 10 mIU/mL or higher. Non-inferiority of TAV to MAV was concluded if the lower limit of the 95% CI for the between-group difference was greater than -5%. Non-inferiority was assessed in the per-protocol set of participants (aged ≥18 years) and superiority was assessed in all participants (aged ≥45 years) who received at least one vaccination and had at least one evaluable immunogenicity sample after baseline (full analysis set). Safety analyses were a secondary outcome and included all participants who received at least one injection. This trial is registered at Clinicaltrials.gov (NCT03393754) and EudraCT (2017-001819-36) and is closed to new participants.

FINDINGS

Between Dec 13, 2017, and April 8, 2019, 1607 participants (796 allocated to TAV and 811 allocated to MAV) were randomly assigned and distributed across age cohorts of 18-44 years (299 of 1607; 18·6%), 45-64 years (716 of 1607; 44·6%), and 65 years and older (592 of 1607; 36·8%). In participants aged 18 years and older, SPR was 91·4% (656 of 718) in the TAV group versus 76·5% (553 of 723) in the MAV group (difference 14·9%, 95% CI 11·2-18·6), showing non-inferiority in the per-protocol set. In participants aged 45 years and older, SPR was 89·4% (559 of 625) in the TAV group versus 73·1% (458 of 627) in the MAV group (difference 16·4%, 95% CI 12·2-20·7), showing superiority in the full analysis set. TAV was associated with higher rates of mild or moderate injection site pain (63·2% [503 of 796] in TAV vs 36·3% [294 of 811] in MAV), tenderness (60·8% [484 of 796] in TAV vs 34·8% [282 of 811] in MAV), and myalgia (34·7% [276 of 796] vs 24·3% [197 of 811] in MAV). Otherwise, the safety profile of TAV was similar to that of MAV.

INTERPRETATION

The safety and efficacy of TAV shows its usefulness for the prevention of HBV infection in adults, including those with stable and controlled chronic conditions.

FUNDING

VBI Vaccines.

The Strategy of Conditionally Replicating Adenovirus-Mediated PreS2 Mini-Antibody Expression Has Dual Effects of Inhibiting HBV Infection and Preventing Hepatocellular Carcinoma

Aim

To investigate the inhibitory effect of hepatitis B virus (HBV) preS2 mini-antibody (mPreS2) against HBV infection, HBV-associated liver injury and HBV-associated hepatic carcinogenesis.

Methods

A recombinant adenovirus vector with the human survivin promoter and mPreS2 gene, Ad5SVP-mPreS2, was constructed. Fluorescence microscopy examination and TCID 50 analysis were utilized to determine the specific proliferation of recombinant adenovirus in liver cancer cells. Western blot analysis was used to determine the mPreS2 expression levels. Enzyme-linked immunosorbent assay (ELISA) was used to examine HBsAg levels to evaluate the inhibitory effect of mPreS2 against HBV infection. The protective effects on hepatic function and preventive effects against hepatic carcinogenesis of Ad5SVP-mPreS2 were studied in diethylnitrosamine (DEN)-treated HBV transgenic Imprinting Control Region mice.

Results

The recombinant adenovirus regulated by the human survivin promoter proliferated exclusively in liver cancer cells rather than normal liver cells. The expression levels of mPreS2 were increased in liver cancer cells compared with normal liver cells, and mPreS2 could be used to recognize liver cells from HBV transgenic mice. ELISA showed that HBsAg levels were decreased in the group treated with Ad5SVP-mPreS2. Ad5SVP-mPreS2 had a protective effect on hepatic function in a DEN-induced liver injury model because of lower serum levels of alanine transaminase and aspartate transaminase. Additionally, HBV transgenic mice treated with Ad5SVP-mPreS2 had fewer and smaller cancerous nodes after induction with DEN than untreated mice.

Conclusion

Conditionally replicating adenovirus-mediated mPreS2 expression inhibited HBV infection and had an inhibitory effect on liver injury and hepatocellular carcinogenesis in HBV transgenic mice.

Inadequate Vaccine Responses in Children With Multiple Sclerosis

Objective: Immunizations against Hepatitis B virus (HBV) and Varicella Zoster virus (VZV), are recommended for patients with pediatric onset multiple sclerosis (POMS) and may be required prior to initiation of some disease modifying therapies. However, the efficacy of routine vaccine administration in POMS has never been studied. We sought to assess the humoral mediated vaccine response to HBV and VZV in children with POMS. Methods: A multi-center retrospective chart-based review of 62 patients with POMS was performed. Clinical data and antibody titers against HBV and VZV were collected prior to initiation of disease modifying therapy or steroids and compared to institutional control data, using t-test and chi squared analysis. Results: There were low rates of immunity against both HBV and VZV (33 and 25% respectively) among individuals with POMS. Fifteen individuals (24%) were non-immune to both. Compared to institutional control data, individuals with POMS were significantly less likely to be immune to and HBV (p = 0.003, 95% CI: 0.22-0.75) and VZV (p < 0.001, 95% CI: 0.09-0.39). Interpretation: Individuals with POMS have low rates of antibody-mediated immunity against HBV and VZV, despite receiving the appropriate vaccinations. This suggests an association between POMS and systemic immune dysregulation although further study is needed.

Hepatitis B virus pre-S region: Clinical implications and applications

Hepatitis B virus (HBV) infection is a major threat to global public health, which can result in many acute and chronic liver diseases. HBV, a member of the family Hepadnaviridae, is a small enveloped DNA virus containing a circular genome of 3.2 kb. Located upstream of the S-open-reading frame of the HBV genome is the pre-S region, which is vital to the viral life cycle. The pre-S region has high variability and many mutations in the pre-S region are associated with several liver diseases, such as fulminant hepatitis (FH), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). In addition, the pre-S region has been applied in the development of several pre-S-based materials and systems to prevent or treat HBV infection. In conclusion, the pre-S region plays an essential role in the occurrence, diagnosis, and treatment of HBV-related liver diseases, which may provide a novel perspective for the study of HBV infection and relevant diseases.

Efficacy and Safety of a 3-Antigen (Pre-S1/Pre-S2/S) Hepatitis B Vaccine: Results of a Phase 3 randomized clinical trial in the Russian Federation

Background

This study compares the immunogenicity and safety of a 3-antigen (S/pre-S1/pre-S2) hepatitis B (HepB) vaccine (3AV), to a single antigen vaccine (1AV) in adults to support the registration of 3AV in Russia.

Methods

We conducted a randomized, double-blind, comparative study of 3-dose regimens of 3AV (10 μg) and 1AV (20 µg) in adults aged 18–45 years. We evaluated immunogenicity based on hepatitis B surface (HBs) antibody titers at days 1, 28, 90, 180, and 210, adverse and serious adverse events (SAEs) to study day 210. The primary outcome was based on the difference in rates of seroconversion at day 210 (lower bound 95% confidence interval [CI]: > − 4%). Secondary outcomes were seroprotection rates (SPR), defined as anti-HBs ≥10 mIU/mL and anti-HBs geometric mean concentration (GMC).

Results

Rate of seroconversion in 3AV (100%) was noninferior to 1AV (97.9%) at study day 210 (difference: 2.1%, 95% CI: −2.0, 6.3%]) but significantly higher at study day 28. SPR at study day 210 was >97% in both arms. Anti-HBs titers were significantly higher at study days 90 (P = .001) and 180 (P = .0001) with 3AV. Sex, age, and body mass index (BMI) had no impact on anti-HBs titers. The rates of local reactions related to vaccination were similar between vaccine arms (3AV vs 1AV) after the first (30% vs 18.8%, P = .15), second (20.0% vs 14.6%, P = .33), and third vaccination (14.9% vs 23.4%, P = .22). No SAEs were reported.

Conclusions

3AV was noninferior to 1AV. 3AV induced high SPR, and there were no safety concerns.

Clinical Trials Registration. NCT04209400.

Antiviral therapy for the sexually transmitted viruses: recent updates on vaccine development

INTRODUCTION

The sexually transmitted infections (STIs) caused by viruses including human T cell leukemia virus type-1 (HTLV-1), human immunodeficiency virus-1 (HIV-1), human simplex virus-2 (HSV-2), hepatitis C virus (HCV), hepatitis B virus (HBV), and human papillomavirus (HPV) are major public health issues. These infections can cause cancer or result in long-term health problems. Due to high prevalence of STIs, a safe and effective vaccine is required to overcome these fatal viruses.

AREAS COVERED

This review includes a comprehensive overview of the literatures relevant to vaccine development against the sexually transmitted viruses (STVs) using PubMed and Sciencedirect electronic search engines. Herein, we discuss the efforts directed toward development of effective vaccines using different laboratory animal models including mice, guinea pig or non-human primates in preclinical trials, and human in clinical trials with different phases.

EXPERT OPINION

There is no effective FDA approved vaccine against the sexually transmitted viruses (STVs) except for HBV and HPV as prophylactic vaccines. Many attempts are underway to develop vaccines against these viruses. There are several approaches for improving prophylactic or therapeutic vaccines such as heterologous prime/boost immunization, delivery system, administration route, adjuvants, etc. In this line, further studies can be helpful for understanding the immunobiology of STVs in human. Moreover, development of more relevant animal models is a worthy goal to induce effective immune responses in humans.

Characterization of hepatitis B virus surface antigen particles expressed in stably transformed mammalian cell lines containing the large, middle and small surface protein

Vaccination still represents the most efficient and inexpensive strategy in the control of hepatitis B virus (HBV) infection. However, about 10% of the population vaccinated with the current yeast derived vaccine, consisting of the non-glycosylated form of the small envelope protein (S) of the HBV, fail to display an adequate immune response. Therefore, there is a need for the development of new vaccines with enhanced immunogenicity. On this regard, new generation vaccines containing L and preS2-containing HBV surface proteins in addition to S, have proven to be able to bypass the lack of response of the standard vaccine. In this work, we describe the development of stable recombinant CHO-K1 and HEK293 cell lines able to produce and secrete hepatitis B subviral envelope particles (HBV-SVPs) composed by the three surface proteins of the HBV. In turn, we demonstrated that these particles induced a specific humoral immune response in experimental animals and triggered the production of antibodies with the ability to recognize the binding site of HBV with the hepatocyte. Thus, these HBV-SVPs represent a promising candidate as a new generation vaccine in order to enhance the immunogenicity of the conventional yeast derived HBV vaccine.

[Vaccination in older adults: compulsory or voluntary exercise?]

BACKGROUND

Immunosenescence leads to an increasing susceptibility to infections. Therefore, vaccination is an essential element of prevention. The recommendations of the permanent vaccination commission (STIKO), a committee at the Robert-Koch-Institute, affiliated to the German Government, are updated every year and include a particular section dealing with older adults.

CURRENT DEVELOPMENTS

Immunosenescence reduces vaccine effectiveness. Thus, older adults and patients with multimorbidity are in need of more immunogenic vaccines. Cell culture derived quadrivalent influenza vaccine, trivalent adjuvanted vaccine and a high dose influenza vaccine show higher immune response in these groups. STIKO actually recommends an adjuvanted herpes zoster subunit vaccine to all adults in the age of 60 and above because of its vaccine effectiveness of 90 % in all age groups. The increasing travel activities of older adults require travel vaccination advice that takes into account travel destination as well as multimorbidity. Adjusted vaccination schedules and controlling of antibody titers have to be considered.

OUTLOOK

New vaccines are under development, that are more immunogenic and therefore more effective (e. g. pneumococcal vaccine) or that prevent infections for which a vaccine was previously not available (e. g. norovirus vaccine).

Immune Determinants in the Acquisition and Maintenance of Antibody to Hepatitis B Surface Antigen in Adults After First-Time Hepatitis B Vaccination

Global implementation of a birth‐dose hepatitis B (HB) vaccine has significantly reduced the prevalence of hepatitis B virus (HBV) carriers. Durable and sufficient titers of antibodies to hepatitis B surface antigen (anti‐HBs) are desirable for vaccinees to gain resistance to HBV exposure. However, the existence of primary nonresponders and vaccinees who lost anti‐HBs over time remains a challenge for the strategy of HBV elimination. We thus aim to clarify the mechanisms of acquisition and maintenance of vaccine‐induced anti‐HBs in healthy adults. We retrospectively analyzed the vaccination records of 3,755 first‐time HB‐vaccinated students and also traced the acquired antibody transition of 392 first‐time vaccinees for 10 consecutive years. To understand the cellular and humoral immune response, we prospectively examined peripheral blood from 47 healthy first‐time HB‐vaccinated students, 62 booster‐vaccinated health care workers, and 20 individuals who maintained their anti‐HBs. In responders, a significant increase of follicular helper T (Tfh) cells, activated plasmablasts, and plasma cells was observed in first‐time‐vaccinated but not booster‐vaccinated persons. We also discovered memory B cells and antibody‐secreting cells were more abundant in individuals who maintained anti‐HBs. According to vaccination records, higher anti‐HBs antibody titer acquisition was related to the longer term maintenance of anti‐HBs, the level of which was positively correlated with prevaccination levels of serum interferon‐γ and related chemokines. The second series of vaccination as a booster provided significantly higher anti‐HBs antibody titers compared to the initial series. Conclusion: Coordinated activation of Tfh and B‐cell lineages after HB vaccination is involved in the acquisition and maintenance of anti‐HBs. Our findings support the rationale of preconditioning the immune status of recipients to ensure durable vaccine responses.

Hepatitis B virus subgenotype F3 reactivation with vaccine escape mutations: A case report and review of the literature

Hepatitis B represents a global health threat because its chronic course and sequelae contribute to a high morbidity and mortality. Hepatitis B virus (HBV) infection can be controlled by vaccines, antiviral treatment, and by interrupting transmission. Rare vaccine escape mutants are serious because they eliminate vaccine protection. Here, we present a 74-year-old vaccinated patient with HBV reactivation 11 years after kidney transplantation. The patient was HBV-positive but HBsAg-negative prior to vaccination 6 years before transplantation. The reactivated virus was HBV genotype F3 with vaccine escape mutations G145R, P120Q, and Q129P. The patient was successfully treated with entecavir. The epidemiological reasons for this subgenotype, which is extremely rare in Western Europe, were unclear. This case illustrates that second-generation vaccines are not always effective in a specific group of patients.

The immune response of rhesus macaques to novel vaccines comprising hepatitis B virus S, PreS1, and Core antigens

Therapeutic vaccines represent a unique approach to hepatitis B virus (HBV) treatment and have the potential to induce long-term control of infection. This study explored the immune responses of rhesus macaques to novel vaccines comprising the S, PreS1, and Core antigens of the HBV that showed promise as prophylactic and therapeutic approaches in a mouse model. The tested vaccines included two DNA vaccines (pVRC-SS1, pVRC-CS1), an HBV particle subunit (HBSS1) vaccine and the recombinant vaccinia virus- (RVJ-) based vaccines (RVJSS1 and RVJCS1) in which SS1 containing S (1-223 aa) and PreS1 (21-47 aa), CS1 containing Core (1-144 aa) and PreS1 (1-42 aa). The humoral immunity and cell-mediated immunity (CMI) induced by vaccines comprising the S, PreS1, and Core antigens of HBV were investigated in a longitudinal study that continued up to 98 weeks after the firstvaccination. In rhesus macaques, anti-PreS1 antibody was induced more rapidly than anti-S or anti-Core antibody after DNA vaccination. The antibody and cell-mediated immune responses against S, PreS1, and C were significantly enhanced in macaques boosted with RVJSS1 and RVJCS1, whereas the cell-mediated response to C was most robust and durable. The immune response to S, PreS1, and C was restored by HBSS1 boosting and detected in macaques until weeks 74 and 98 after the first vaccination. Additionally, robust neutralizing activity was detected at week 52. In conclusion, novel HBV vaccine candidates, especially those used for therapeutic applications should incorporate the PreS1 and Core antigens.

A virus-like particle of the hepatitis B virus preS antigen elicits robust neutralizing antibodies and T cell responses in mice

The preS antigen of hepatitis B virus (HBV) corresponds to the N-terminal polypeptide in the large (L) antigen in addition to the small (S) antigen. The virus-like particle (VLP) of the S antigen is widely used as a vaccine to protect the population from HBV infection. The presence of the S antigen and its antibodies in patient blood has been used as markers to monitor hepatitis B. However, there is very limited knowledge about the preS antigen. We generated a preS VLP that is formed by a chimeric protein between preS and hemagglutinin (HA), and the matrix protein M1 of influenza virus. The HBV preS antigen is displayed on the surface of preS VLP. Asn112 and Ser98 of preS in VLP were found to be glycosylated and O-glycosylation of Ser98 has not been reported previously. The preS VLP shows a significantly higher immunogenicity than recombinant preS, eliciting robust anti-preS neutralizing antibodies. In addition, preS VLP is also capable of stimulating preS-specific CD8⁺ and CD4⁺ T cell responses in Balb/c mice and HBV transgenic mice. Furthermore, preS VLP immunization provided protection against hydrodynamic transfection of HBV DNA in mice. The data clearly suggest that this novel preS VLP could elicit robust immune responses to the HBV antigen, and can be potentially developed into prophylactic and therapeutic vaccines.

Recombinant vaccinia vector-based vaccine (Tiantan) boosting a novel HBV subunit vaccine induced more robust and lasting immunity in rhesus macaques

This study explored several prime-boost strategies in rhesus macaques using various novel hepatitis B virus (HBV) vaccines that showed promise as prophylactic and therapeutic approaches in our previous study using in a mouse model. The tested vaccines included an HBV particle subunit (HBSS1) vaccine and the recombinant vaccinia (RVJSS1) or adenoviral (rAdSS1) vector-based vaccines containing S (1-223aa) and PreS1 (21-47aa). The strength and maintenance of humoral activity (IgG and neutralizing antibodies) and cellular immunity (interferon-γ production assessed by IFN-γ enzyme-linked immunosorbent spot (ELISpot) assay) were investigated in a longitudinal study following various vaccination protocols until 79weeks post-vaccination. We found that HBSS1/RVJSS1 heterologous prime-boost elicits similar strong humoral immunity but more robust and lasting cellular immunity (CMI) than HBSS1/HBSS1 homologous vaccination in rhesus macaques. Furthermore, HBSS1/RVJSS1/RVJSS1 induced more robust and lasting CMI in macaques than did HBSS1/HBSS1/rAdSS1 vaccination. Therefore, HBSS1/RVJSS1/RVJSS1 is most promising candidates for protecting humans against HBV infection, especially for therapeutic application.

A randomized, controlled clinical trial to evaluate the immunogenicity of a PreS/S hepatitis B vaccine Sci-B-Vac™, as compared to Engerix B®, among vaccine naïve and vaccine non-responder dialysis patients

BACKGROUND

Dialysis patients have a suboptimal response to hepatitis B (HBV) vaccination. This study aimed to compare the immunogenicity of two vaccines: the third-generation Sci-B-Vac™ vs. the second-generation Engerix B^®. The cohort included two groups of dialysis patients: naïve and previously vaccinated non-responders. Primary endpoints were antibody titers ≥10 IU/L at 3 and 7 month post-vaccination. Secondary objectives were seroprotection rates in vaccine-naïve patients and in previously vaccinated non-responders.

METHODS

Eighty-six patients were assigned to vaccine (Sci-B-Vac™ or Engerix B^®) using computer-generated randomization, stratified by age, gender, diabetes, and previous HBV vaccination. Sci-B-Vac™ was administered in three doses, 10 μg, at 0, 1, and 6 months in naïve patients; or 20 μg in previously vaccinated non-responders. Engerix B^® included four doses, 40 μg at 0, 1, 2, and 6 months.

RESULTS

Each group had 43 patients. Seroconversion was 69.8% with Engerix B^® vs. 73.2% with Sci-B-Vac™. Antibody titers at 7 months were higher with Sci-B-Vac™ (266.4 ± 383.9, median 53.4) than with Engerix^® (193.2 ± 328.9, median 19). However, these differences were not significant, perhaps due to a suboptimal sample size.

CONCLUSIONS

This study suggests comparable immunogenicity for both vaccines. Thus, we cannot reject the null hypothesis that there is no difference in seroconversion by vaccine type. It is noteworthy that naïve patients were vaccinated with a standard dose of Sci-B-Vac™, while Engerix B^® was administered at a double dose. Similarly, although mean antibody titer levels in the Sci-B-Vac™ group were higher than in the Engerix^® group, this difference did not reach significance. Consequently, a future clinical trial should recruit a larger cohort of patients, using a standard double-dose protocol in both groups.

A Pre-Clinical Safety Evaluation of SBP (HBsAg-Binding Protein) Adjuvant for Hepatitis B Vaccine

Although adjuvants are a common component of many vaccines, there are few adjuvants licensed for use in humans due to concerns about their toxic effects. There is a need to develop new and safe adjuvants, because some existing vaccines have low immunogenicity among certain patient groups. In this study, SBP, a hepatitis B surface antigen binding protein that was discovered through screening a human liver cDNA expression library, was introduced into hepatitis B vaccine. A good laboratory practice, non-clinical safety evaluation was performed to identify the side effects of both SBP and SBP-adjuvanted hepatitis B vaccine. The results indicate that SBP could enhance the HBsAg-specific immune response, thus increasing the protection provided by the hepatitis B vaccine. The safety data obtained here warrant further investigation of SBP as a vaccine adjuvant.

[Vaccination against hepatitis B: success and challenges]

Hepatitis B virus is a worldwide leading cause of acute and chronic liver disease including cirrhosis and hepatocellular carcinoma. Effective vaccines have been available since the early '80s. Vaccination against hepatitis B virus infection has proved highly successful in reducing the disease burden, the development of the carrier state and the hepatitis B-related morbidity and mortality in the countries where vaccination has been implemented. Despite success and efficacy of preventive vaccines, a huge number of chronically infected patients still remain. Therapeutic vaccination may prove to be useful coupled with current antivirals and other immunomodulatory approaches to treat these patients. This review summarizes current unresolved issues and future perspectives on vaccination required for global cure of hepatitis B virus infection.

Immunotherapy With the PreS-based Grass Pollen Allergy Vaccine BM32 Induces Antibody Responses Protecting Against Hepatitis B Infection

Background

We have constructed and clinically evaluated a hypoallergenic vaccine for grass pollen allergy, BM32, which is based on fusion proteins consisting of peptides from the IgE binding sites of the major grass pollen allergens fused to preS (preS1 + preS2), a domain of the hepatitis B virus (HBV) large envelope protein which mediates the viral attachment and entry. Aim of this study was the characterization of the HBV-specific immune response induced by vaccination of allergic patients with BM32 and the investigation of the vaccines' potential to protect against infection with HBV.

Methods

Hepatitis B-specific antibody and T cell responses of patients vaccinated with BM32 were studied using recombinant preS and synthetic overlapping peptides spanning the preS sequence. The specificities of the antibody responses were compared with those of patients with chronic HBV infection. Furthermore, the capacity of BM32-induced antibodies, to inhibit HBV infection was investigated using HepG2-hNTCP cell-based in vitro virus neutralization assays.

Findings

IgG antibodies from BM32-vaccinated but not of HBV-infected individuals recognized the sequence motif implicated in NTCP (sodium-taurocholate co-transporting polypeptide)-receptor interaction of the hepatitis B virus and inhibited HBV infection.

Interpretation

Our study demonstrates that the recombinant hypoallergenic grass pollen allergy vaccine BM32 induces hepatitis B-specific immune responses which protect against hepatitis B virus infection in vitro.

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BM32 is a recombinant allergy vaccine consisting of the preS domain of the large envelope protein of hepatitis B virus (HBV) and allergen-derived peptides.

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Vaccination of allergic patients with BM32 induced preS-specific antibodies which inhibit hepatitis B infection in vitro.

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BM32 may be useful as therapeutic vaccine in HBV-infected patients.

Infection with HBV remains a major cause of morbidity and mortality worldwide. Conventional HBV vaccines, consisting of SHBs particles solely, do not elicit adequate antibody production in 5–10% of vaccines and there is a need for therapeutic HBV vaccines. We have engineered an allergy vaccine which consists of allergen-derived peptides fused to the preS domain of the large envelope protein of HBV. Here we show that vaccination of allergic patients with this vaccine induces antibodies which protect against HBV infection in vitro. The preS-containing allergy vaccine may thus be also useful for therapeutic vaccination of HBV-infected patients.

Sci-B-VacTM Vs ENGERIX-B Vaccines for Hepatitis B Virus in Patients with Inflammatory Bowel Diseases: A Randomised Controlled Trial

BACKGROUND AND AIMS

Response rate to second-generation hepatitis B virus vaccines is relatively low in patients with inflammatory bowel diseases compared with the general healthy population. We compared the efficacy and safety of a third- vs a second-generation hepatitis B virus vaccine in a group of patients with inflammatory bowel diseases treated with immunosuppressive medications.

METHODS

Prospective, randomised, single-blind, controlled study. Eligible patients were randomly assigned to receive one of two vaccines, ENGERIX-B or Sci-B-Vac. The vaccines were administered in three doses at 0, 1, and 6 months. The primary endpoint was defined as the titre of anti-hepatitis B S [HBs] antibodies following the standard three-dose hepatitis B virus vaccination schedule.

RESULTS

A total of 72 patients complied with study protocol [37 and 35 patients in the ENGERIX-B and Sci-B-Vac groups, respectively]. Overall, 75% of the cohort seroconverted. The primary endpoint was met in 81.1% in the ENGERIX-B group and 68.6% in the Sci-B-Vac group [p = 0.22]. Patients in the Sci-B-Vac group showed a statistically significant decreased seroconversion rate compared with the ENGERIX-B group, with use of tumour necrosis factor [TNF] alpha inhibitors [p = 0.03], and higher degree of disease activity [p = 0.03].

CONCLUSIONS

Overall seroconversion rate in our cohort was higher than in previous reports in the literature, possibly due to a low disease activity state in the majority of participants. Third-generation hepatitis B virus vaccines showed no apparent advantage over standard of care vaccine in this patient group.

Effect of Tetanus-diphtheria Vaccine on Immune Response to Hepatitis B Vaccine in Low-responder Individuals

Background:

Conventional hepatitis B virus (HBV) vaccination fails to achieve efficient protection in about 5–10% of the world population. Hence, different strategies have been adopted to ameliorate HBV antibody titers. This study aimed to evaluate the concurrent application of tetanus-diphtheria (Td) and HBV vaccination on hepatitis B surface (HBs) antibody titer in low-responder healthy individuals.

Methods:

This was a randomized clinical trial, which was implemented among 140 of medical staff working as health-care workers assumed as low-responders. The subjects were randomly allocated to either control or interventional groups. The control and interventional groups received HBV recombinant vaccine while the latter group was also vaccinated through Td. Enzyme-linked immunosorbent assay was applied to measure HBs antibody (HBsAb) titers just before and 6 months after the last vaccination. All data were entered into SPSS software. Independent t-test, paired t-test, and Chi-square or Fisher's exact test were applied for data comparison.

Results:

Antibody titers of the subjects in the intervention and control groups soared from 49.08 ± 20.08 IU/L to 917.78 ± 204.80 IU/L and from 46.95 ± 18.55 to 586.81 ± 351.77 IU/L, respectively (both P < 0.001); nevertheless, by comparison with control group, variation of antibody titer in the interventional group was significantly higher (P < 0.001).

Conclusions:

Concurrent application of Td and HBV vaccine could effectively enhance protective levels of HBsAb titers in low-responder individuals.

Localization of immunodominant epitopes within the "a" determinant of hepatitis B surface antigen using monoclonal antibodies

The common "a" determinant is the major immunodominant region of hepatitis B surface antigen (HBsAg) shared by all serotypes and genotypes of hepatitis B virus (HBV). Antibodies against this region are thought to confer protection against HBV and are essential for viral clearance. Mutations within the "a" determinant may lead to conformational changes in this region, which can affect the binding of neutralizing antibodies. There is an increasing concern about identification and control of mutant viruses which is possible by comprehensive structural investigation of the epitopes located within this region. Anti-HBs monoclonal antibodies (mAbs) against different epitopes of HBsAg are a promising tool to meet this goal. In the present study, 19 anti-HBs mAbs were employed to map epitopes localized within the "a" determinant, using a panel of recombinant mutant HBsAgs. The topology of the epitopes was analyzed by competitive enzyme-linked immunosorbent assay (ELISA). Our results indicate that all of the mAbs seem to recognize epitopes within or in the vicinity of the "a" determinant of HBsAg. Different patterns of binding with mutant forms were observed with different mAbs. Amino acid substitutions at positions 123, 126, 129, 144, and 145 dramatically reduced the reactivity of antibodies with HBsAg. The T123N mutation had the largest impact on antibody binding to HBsAg. The reactivity pattern of our panel of mAbs with mutant forms of HBsAg could have important clinical implications for immunoscreening, diagnosis of HBV infection, design of a new generation of recombinant HB vaccines, and immunoprophylaxis of HBV infection as an alternative to therapy with hepatitis B immune globulin (HBIG).

Current trends in hepatitis B vaccination

One of the major successes in the area of vaccinology is the emergence, development and usage of hepatitis B vaccine (a prophylactic vaccine against HBV). Hepatitis B vaccine has protected millions of individuals from acquiring HBV infection and has prevented liver cancer in the majority of vaccinated subjects. Although initially designed as prophylactic vaccines, accumulative evidence has shown that these vaccines may also be used to treat patients with chronic hepatitis B. At present, there are two main areas of discussion in hepatitis B vaccination; development of more effective prophylactic hepatitis B vaccine that can provide protection to all vaccine recipients, and designing hepatitis B-based therapeutic vaccines for treatment of chronic hepatitis B patients.

Immunogenicity of parenterally delivered plant-derived small and medium surface antigens of hepatitis B virus

Intramuscularly delivered plant-derived M-HBsAg was compared to S-HBsAg, and as a result elicited specific anti-preS2 antibodies and significantly higher titre of anti-HBs antibodies, together with IgG isotype profile indicating some Th1 polarisation, apart from the main Th2 response. HBV prevalence is still threatening, regardless of prevention programmes using vaccines containing S-HBsAg, supplemented by third-generation vaccines, comprising also M- and L-HBsAg. Plant expression systems offer a cost-effective production option of the antigens. Plant-derived S- and M-HBsAg, intramuscularly delivered to mice, elicited anti-HBs antibodies several times higher than high responsiveness threshold titre. M-HBsAg induced stronger response of anti-HBs and also specific anti-preS2 antibodies. IgG isotype profiles indicated mainly Th2 response, yet Th1 polarisation was also pointed out, in some larger extent for M-HBsAg. These results correspond to research on CHO-derived M-HBsAg vs. commercial vaccines based on S-HBsAg and support potency of plant-derived antigens as alternative injection vaccines.

Deltex1 Polymorphisms Are Associated with Hepatitis B Vaccination Non-Response in Southwest China

Background

Hepatitis B vaccination is the most important tool available for preventing hepatitis B virus (HBV) infection and reducing the prevalence of infection. However, epidemiological studies have demonstrated that morethan 5% of patients exhibit a non- or hypo-response to the HBV vaccine. Genetic variations associated with T cell immunity contribute to the immune response to HBV vaccination. The deltex 1 (DTX1) gene is involved in T cell anergy, which may also be associated with the immune response to the HBV vaccination.

Methods

We detected 10 single nucleotide polymorphisms (SNPs) in or around the DTX1 gene in 601 infants out of a population from Southwest China, including 299 high responders(HRs; HBsAb > 100 mIU/mL) and 302 non-responders (NRs; HBsAb < 10 mIU/mL). An additional validation study was performed, comprising 230 adult patients(135 HRs and 95 NRs) from Southwest China.

Results

This study found that the minor allele ‘G’ of rs2384077 (adjusted p = 2.63E^-04,) and the minor allele ‘C’ of rs10744794 (adjusted p = 3.69E^-04) in the first intron of the DTX1 gene were remarkably associated with the immune response to HBV vaccination in both infant and adult populations. Moreover, a subsequent analysis indicated that haplotypes (A-T, G-C) of the two SNPs were significantly associated with the immune response to HBV vaccination.

Conclusions

Two SNPs (rs2384077 and rs10744794) in an intron of DTX1 and the linkage disequilibrium (LD) block are significantly associated with the immune response to HBV vaccination. The functional element annotation of the LD block between the two SNPs contains four transcriptional regulatory elements. The results suggest that these two SNPs may be involved in the immune response to HBV vaccination.

Inhibition of preS1-hepatocyte interaction by an array of recombinant human antibodies from naturally recovered individuals

Neutralizing monoclonal antibodies are being found to be increasingly useful in viral infections. In hepatitis B infection, antibodies are proven to be useful for passive prophylaxis. The preS1 region (21–47a.a.) of HBV contains the viral hepatocyte-binding domain crucial for its attachment and infection of hepatocytes. Antibodies against this region are neutralizing and are best suited for immune-based neutralization of HBV, especially in view of their not recognizing decoy particles. Anti-preS1 (21–47a.a.) antibodies are present in serum of spontaneously recovered individuals. We generated a phage-displayed scFv library using circulating lymphocytes from these individuals and selected four preS1-peptide specific scFvs with markedly distinct sequences from this library. All the antibodies recognized the blood-derived and recombinant preS1 containing antigens. Each scFv showed a discrete binding signature, interacting with different amino acids within the preS1-peptide region. Ability to prevent binding of the preS1 protein (N-terminus 60a.a.) to HepG2 cells stably expressing hNTCP (HepG2-hNTCP-C4 cells), the HBV receptor on human hepatocytes was taken as a surrogate marker for neutralizing capacity. These antibodies inhibited preS1-hepatocyte interaction individually and even better in combination. Such a combination of potentially neutralizing recombinant antibodies with defined specificities could be used for preventing/managing HBV infections, including those by possible escape mutants.

Vaccination Against Hepatitis B Virus (HBV) in HIV-1-Infected Patients With Isolated Anti-HBV Core Antibody: The ANRS HB EP03 CISOVAC Prospective Study

BACKGROUND

Although an isolated anti-hepatitis B virus (HBV) core antibody (anti-HBc) serological profile is frequent in human immunodeficiency virus (HIV)-infected patients, data on HBV vaccination in these patients are scarce.

METHODS

A prospective multicenter study was conducted to assess the immunogenicity of HBV vaccination in 54 patients with an isolated anti-HBc profile and undetectable HIV load. They were vaccinated with 1 dose (20 µg) of recombinant HBV vaccine. Those with an anti-HBV surface antibody (anti-HBs) level of <10 mIU/mL 4 weeks after vaccination received 3 additional double doses (40 µg) at weeks 5, 9, and 24.

RESULTS

At week 4, 25 patients (46%) were responders. Only the ratio of CD4(+) T cells to CD8(+) T cells was associated with this response in multivariate analysis (odds ratio for +0.1, 1.32; 95% confidence interval, 1.07-1.63; P = .008). At week 28 and month 18, 58% of these patients (14 of 24) and 50% (10 of 20), respectively, maintained anti-HBs level of ≥10 mIU/mL.Among nonresponding patients at week 4, who received further vaccinations, 89% (24 of 27) and 81% (21 of 26) had an anti-HBs level of ≥10 mIU/mL at week 28 and month 18, respectively. The preS2-specific interferon γ T-cell response increased between week 0 and week 28 in patients who finally responded to reinforced vaccination (P = .03).

CONCLUSIONS

All of the patients with an isolated anti-HBc profile who did not have an anti-HBs titer of >100 mIU/mL 4 weeks after a single recall dose of HBV vaccine should be further vaccinated with a reinforced triple double-dose scheme.

Donor- and recipient-derived immunity in ABO incompatible living-related liver transplantation

This report describes how donor- and recipient-derived immunity was influenced by immunosuppressive treatment of ABO incompatibility (rituximab and immunoadsorption/plasmaphereses) in the long-term. We present an 8-year course of Hepatitis B virus (HBV) immunity, isohemagglutinins and B cell numbers. Whereas cellular HBV immunity was transferred from the HBV vaccinated donor (blood group A1) to the HBV naïve recipient (blood group 0), humoral HBV specific immune transfer was lacking. Starting at month 17 after transplantation, the recipient was vaccinated six times against HBV. Anti-HBs did not appear until the sixth vaccination at month 44. Immunoadsorption prior to transplantation reduced anti-A1 IgG titers from 256 to 2. Titers after transplantation remained low (⩽64). B cell numbers were below standard values up to month 26, then normalized and exceeded normal values from year 7 to 8 post transplantation. In conclusion, donor-derived B cell immunity was lost but recipient-derived immunity persisted after ABO incompatible transplantation.

Studies of nosocomial outbreaks of hepatitis B in nursing homes in Germany suggest a major role of hepatitis B e antigen expression in disease severity and progression

Hepatitis B virus (HBV) causes acute or chronic hepatitis B. Local outbreaks of HBV infections in skilled nursing facilities is a matter of growing concern in developed countries. Here, we investigated two outbreaks of hepatitis B that recently occurred in nursing homes in Germany. The outbreak at location A was associated with acute fulminant hepatitis with fatal outcome in several cases, while individuals infected at location B developed asymptomatic or mild hepatitis B. Sequence analysis of viruses involved in these outbreaks revealed different, but unique HBV strains for each location. Each of the strains produced high viremia of more than 10(9) virions/mL serum. We found that the mild course of hepatitis B at location B was caused by a circulating wild-type HBV genotype A2 strain, which is commonly found in Central Europe. Complete genome sequences of isolates obtained from infected patients revealed nearly 100% sequence identity at the nucleotide level as well as expression of HBV e protein (HBeAg), a known T cell tolerogen in the incubation or chronic phases of HBV infection. By contrast, the outbreak at location A was associated with an HBV genotype D2 variant that lacked HBeAg expression, suggesting that immunopathology and selection of specific HBV variants played a major role in the severe (or even fulminant) acute hepatitis observed at location A. Importantly, all patients were diagnosed with type 2 diabetes mellitus, a known risk factor for healthcare-associated transmission of HBV. The study leads us to suggest that, besides strict adherence to hygiene standards, additional efforts are required to reduce the risk of HBV transmission and fulminant disease progression in healthcare settings and nursing homes. In this context, a general screening for HBsAg and active hepatitis B vaccination should be considered for people living in nursing homes, especially for those with diagnosed diabetes or other predisposing factors for HBV transmission.

Applications of human hepatitis B virus preS domain in bio- and nanotechnology

Human hepatitis B virus (HBV) is a member of the family Hepadnaviridae, and causes acute and chronic infections of the liver. The hepatitis B surface antigen (HBsAg) contains the large (L), middle (M), and small (S) surface proteins. The L protein consists of the S protein, preS1, and preS2. In HBsAg, the preS domain (preS1 + preS2) plays a key role in the infection of hepatocytic cells by HBV and has several immunogenic epitopes. Based on these characteristics of preS, several preS-based diagnostic and therapeutic materials and systems have been developed. PreS1-specific monoclonal antibodies (e.g., MA18/7 and KR127) can be used to inhibit HBV infection. A myristoylated preS1 peptide (amino acids 2-48) also inhibits the attachment of HBV to HepaRG cells, primary human hepatocytes, and primary tupaia hepatocytes. Antibodies and antigens related to the components of HBsAg, preS (preS1 + preS2), or preS1 can be available as diagnostic markers of acute and chronic HBV infections. Hepatocyte-targeting delivery systems for therapeutic molecules (drugs, genes, or proteins) are very important for increasing the clinical efficacy of these molecules and in reducing their adverse effects on other organs. The selective delivery of diagnostic molecules to target hepatocytic cells can also improve the efficiency of diagnosis. In addition to the full-length HBV vector, preS (preS1 + preS2), preS1, and preS1-derived fragments can be useful in hepatocyte-specific targeting. In this review, we discuss the literature concerning the applications of the HBV preS domain in bio- and nanotechnology.

Unsolved problems and future perspectives of hepatitis B virus vaccination

Hepatitis B virus (HBV) infection is still a serious worldwide problem, and vaccination is the most effective strategy for primary prevention of the infection. Although universal vaccination may be required for total eradication, several countries, including Japan, have not yet adopted universal vaccination programs. Some individuals are non-responders to HBV vaccine and several mechanisms responsible for their poor response have been proposed. To overcome non-response, third generation vaccines with pre-S proteins have been developed. These vaccines have shown better anti-HBs responses and may also be effective in preventing infection by HBV with S mutant. Improvement of vaccine efficacy by intradermal administration, or co-administration with cytokines or adjuvants, may also be effective in non-responders. The necessity, timing and method of booster vaccination in responders with decreased anti-HBs responses, and effective vaccination against S-mutant HBV, are issues requiring resolution in the global prevention of HBV infection.

Inadequate activation of the HBsAg-specific Th cells by APCs leads to hyporesponsiveness to HBsAg vaccine in B10.S mice

Hepatitis B can be effectively prevented by hepatitis B vaccination. However, hyporesponse to the hepatitis B vaccine has been found in both human and inbred mice with particular MHC alleles or haplotypes, but the mechanisms underlying this poor response remains elusive. In the present study, we investigated the mechanisms underlying the hyporesponse to hepatitis B vaccination using B10.S-H2s/SgMcdJ (B10.S, H-2(s), poor responder) and C57BL/10J (B10, H-2(b), good responder) mice. We observed that the B10.S mice displayed a hyporesponse to HBsAg vaccine but a normal response to 3 other foreign antigens (influenza A (H1N1) 2009 monovalent vaccine, tetanus toxoid and ovalbumin). In B10.S mice immunized with HBsAg, the levels of serum anti-HBs IgG, the number of HBsAg-specific IgG-secreting plasma cells and HBsAg-specific Th cells were considerably lower than that in B10 mice. Further, the findings of the insufficient maturation (CD86), co-stimulation (CD40) and migration (CCR7) activities of DCs together with the inadequate activation of the HBsAg-specific Th cells by APCs were identified as part of the reason for the HBsAg hyporesponse in B10.S mice, which supports the hypothesis that measures aimed at promoting the maturation, co-stimulation or migration of APCs to enhance Th cell activation may be a useful strategy for the development of new hepatitis B vaccines.

Development of a novel IGRA assay to test T cell responsiveness to HBV antigens in whole blood of chronic Hepatitis B patients

BACKGROUND

Interferon gamma release assays (IGRA) have been developed to support easy and fast diagnosis of diseases like tuberculosis, and CMV in transplant patients. IGRAs focus on cellular immunity especially memory T cells and thus also allow rapid screening prior to complex flow cytometric testing. Here, we describe a novel, sensitive whole blood based cytokine release assay capable of assessing T cell responsiveness to HBV antigens in Hepatitis B patients and assessing hepatitis B vaccination status in healthy individuals.

METHODS

Seventy two chronic Hepatitis B patients (CHB), 8 acute hepatitis B patients (AHB) and 80 healthy controls (HC) were tested by ELISA for IFNγ- and IL2-secretion in whole blood after challenge with synthetic peptide libraries of hepatitis B core antigen (HBcAg) or hepatitis B surface antigen (HBsAg).

RESULTS

The developed IGRA test reliably differentiated between Hepatitis B patients, vaccinees and unvaccinated healthy controls. Treatment naïve and treated CHB patients showed a weaker IFNγ response to HBcAg (16 ± 5 and 35 ± 28 pg/ml, respectively) compared to the AHB group (82 ± 39 pg/ml), whereas HC remained unresponsive (6 ± 1 pg/ml). IL2 levels after HBcAg challenge were also higher in the AHB group compared to naive and treated CHB as well as HC (47 ± 21 vs. 12 ± 3, 15 ± 10 and 12 ± 9 pg/ml, respectively). HBsAg stimulation led to increased IFNγ and IL2 levels in the AHB group (33 ± 12 and 22 ± 12 pg/ml) and even higher levels in HC due to a high hepatitis B vaccination rate (41 ± 10 and 167 ± 58 pg/ml). Naive and treated CHB patients developed no or only weaker IFNγ or IL2 responses to HBsAg (5 ± 2 and 12 ± 7 pg/ml, for naive CHB, 12 ± 10 and 18 ± 15 pg/ml, for treated CHB). For HC, IL2 release after HBsAg stimulation depicted hepatitis B vaccination status with a diagnostic sensitivity and specificity of 85 % and 90 %.

CONCLUSION

Our novel whole blood based cytokine release assay constitutes an easy and robust tool for screening HBV specific cellular immunity as alternative to flow cytometry or ELISPOT assays.

Prophylactic vaccination against hepatitis B: achievements, challenges and perspectives

Large-scale vaccination against hepatitis B virus (HBV) infection started in 1984 with first-generation vaccines made from plasma of chronic carriers containing HBV surface antigen (HBsAg). Thereafter, it was replaced in most countries by second-generation vaccines manufactured in yeast cells transformed with gene S encoding HBsAg. Both generations of vaccines have been applied for universal neonate and early childhood vaccination worldwide and have led to a 70-90 % decrease in chronic HBV carrier rates. However, 10-30% of newborns from HBsAg/HBeAg-positive mothers cannot be protected by passive/active vaccination alone and become chronic HBV carriers themselves. Asymptomatic occult HBV infections are frequent even in those who have protective levels of anti-HBs. Suboptimal protection may be due to heterologous HBsAg subtypes that are present in 99% of HBV carriers worldwide. Second-generation vaccines contain partially misfolded HBsAg and lack preS1 antigen that carries the major HBV attachment site and neutralizing epitopes. Third-generation vaccines produced in mammalian cells contain correctly folded HBsAg and neutralizing epitopes of the preS antigens, induce more rapid protection, overcome nonresponse to second-generation vaccines and, most importantly, may provide better protection for newborns of HBV-positive mothers. PreS/S vaccines expressed in mammalian cells are more expensive to manufacture, but introduction of more potent HBV vaccines should be considered in regions with a high rate of vertical transmission pending assessment of health economics and healthcare priorities. With optimal vaccines and vaccination coverage, eradication of HBV would be possible.