Effects of vaccine-acquired polyclonal anti-HBs antibodies on the prevention of HBV infection of non-vaccine genotypes

Molecular Characterization of Hepatitis B Virus in People Living with HIV in Rural and Peri-Urban Communities in Botswana

(1) Background: Hepatitis B virus (HBV) sequencing data are important for monitoring HBV evolution. We aimed to molecularly characterize HBV sequences from participants with HBV surface antigen-positive (HBsAg+) serology and occult hepatitis B infection (OBI+). (2) Methods: We utilized archived plasma samples from people living with human immunodeficiency virus (PLWH) in Botswana. HBV DNA was sequenced, genotyped and analyzed for mutations. We compared mutations from study sequences to those from previously generated HBV sequences in Botswana. The impact of OBI-associated mutations on protein function was assessed using the Protein Variation Effect Analyzer. (3) Results: Sequencing success was higher in HBsAg+ than in OBI+ samples [86/128 (67.2%) vs. 21/71 (29.2%)]. Overall, 93.5% (100/107) of sequences were genotype A1, 2.8% (3/107) were D3 and 3.7% (4/107) were E. We identified 13 escape mutations in 18/90 (20%) sequences with HBsAg coverage, with K122R having the highest frequency. The mutational profile of current sequences differed from previous Botswana HBV sequences, suggesting possible mutational changes over time. Mutations deemed to have an impact on protein function were tpQ6H, surfaceV194A and preCW28L. (4) Conclusions: We characterized HBV sequences from PLWH in Botswana. Escape mutations were prevalent and were not associated with OBI. Longitudinal HBV studies are needed to investigate HBV natural evolution.

Hybrid large hepatitis B surface protein composed of two viral genotypes C and D induces strongly cross-neutralizing antibodies

Hepatitis B virus (HBV) vaccination is known to effectively decrease the risk of HBV infection. However, several issues need to be addressed in order to develop an improved HBV vaccine. Although the HBV vaccine has been shown to be effective, this vaccine needs to be more efficacious in defined groups, including non-responders (i.e., individuals who do not develop a protective response even after vaccination) and in health care workers and travelers who require rapid protection. Furthermore, it has been reported that universal HBV vaccination has accelerated the appearance of vaccine-escape mutants resulting from the accumulation of mutations altering the "a" determinant of the hepatitis B surface (HBs) protein. To address these problems, we have been focusing on the large HBs (LHBs) protein, which consists of three domains: pre-S1, pre-S2, and S (in N- to C-terminal order). To enhance the immunogenicity of LHBs, we developed a yeast-derived hybrid LHBs (hy-LHBs) antigen composed of the LHBs proteins from two distinct genotypes (Genotypes C and D). The levels of antibodies induced by hy-LHBs immunization were high not only against S, but also against the pre-S1 and pre-S2 domains. Additionally, hy-LHBs immunization induced significantly more strongly cross-reactive neutralizing antibodies than did small HBs (SHBs) or LHBs of any genotype alone. These findings suggested that hy-LHBs might serve as a candidate antigen for use in an improved prophylactic HBV vaccine.

Impaired long-term anti-HBs responses in choronic hepatitis C patients: Results from a five-year follow-up study with healthy control

Although hepatitis B virus (HBV) vaccination is recommended for hepatitis C virus (HCV)-infected individuals to avoid HBV superinfection, the persistence of their humoral and cell-mediated immunity responses to HBV vaccination is still under investigation. Patients with chronic hepatitis C (CHC) and matched healthy controls, who completed three doses of hepatitis B vaccine (HepB) in 2014, were followed up five years later. One booster dose of HepB was given to those with antibody against hepatitis B surface antigen (anti-HBs) lower than 10mIU/mL. Anti-HBs was tested at follow-up and on the 14th day after the booster dose, as well as HBsAg specific spot-forming cells of interferon γ and interleukin (IL) 2, 4, 5, and 6. At five years, only 56.58% of the CHC patients had sero-protective titers (≥10mIU/mL) of anti-HBs, compared to 70.83% in the controls (P < .05). Similarly, the geometric mean concentration (GMC) of anti-HBs in CHC patients was significantly lower than that in controls (16.95 vs 37.34 mIU/mL, P < .05). After the booster, both GMC and the rate of anamnestic response increased to a very high level in the two groups and the difference between them disappeared (P > .05). Multivariable analysis showed that HCV infection was an independent predictor factor to anti-HBs level at follow-up. HBsAg specific IL-6 was stronger in the CHC patients compared to the controls (P < .05). The data indicate that the durability of protective anti-HBs is poorer in CHC patients compared to healthy individuals, and impaired long-term anti-HBs responses might be associated with the increased HBsAg specific IL-6 responses.

[Neutralization of hepatitis B virus with vaccine-escape mutations by novel hepatitis B vaccine with large-HBs antigen]

Although the current hepatitis B (HB) vaccine comprising yeast-derived small hepatitis B surface antigen (HBsAg) is potent and safe and used worldwide, specific concerns should not be ignored, such as the attenuated prophylaxis against hepatitis B virus (HBV) infection with specific amino acid polymorphisms, called vaccine-escape mutations (VEMs). We investigated a novel HB vaccine consisting of large-HBsAg that covers the shortcomings of the current HB vaccine in a nonhuman primate model. The yeast-derived large-HBsAg was mixed with the adjuvant and used to immunize rhesus macaques, and the induction of antibodies to HBsAg was compared with that of the current HB vaccine. The current HB vaccine predominantly induced antibodies to small-HBsAg, whereas immunization with the large-HBsAg vaccine mainly induced antibodies to the preS1 region. Although the antibodies induced by the current HB vaccine could not prevent infection of HBV with VEMs, the large-HBsAg vaccine-induced antibodies neutralized infection of HBV with VEMs at levels similar to those of the wild type. The HBV genotypes that exhibited attenuated neutralization by induced antibodies differed between these vaccines. In conclusion, the novel HB vaccine consisting of large-HBsAg was revealed to be useful to compensate for shortcomings of the current HB vaccine. The combined use of these HB vaccines may be able to induce antibodies that can neutralize HBV strains with VEMs or multiple HBV genotypes.

Chronic Viral Hepatitis in Elite Athletes: Approaches to Risk Assessment, Prevention and Management

Elite athletes who participate in contact sports are at risk of bleeding injuries, leading to transmission of blood-borne viruses including hepatitis type B, C and D (HBV, HCV and HDV) capable of causing chronic liver disease, liver failure and liver cancer. In view of the significant advances in the viral hepatitis field over the past decade, more structured approaches should be in place to screen for and manage viral hepatitis in elite athletes. HBV status should be assessed in all elite athletes, and those infected should receive nucleos(t)ide analogues for viral suppression, while uninfected individuals should receive HBV vaccination. The all-oral direct acting antivirals for HCV are highly effective and safe, thus the remaining challenge with hepatitis C is case identification and linkage to care. HDV is only found in HBV-infected individuals, which is characterized by rapid disease progression and higher rates of cirrhosis and liver cancer in infected subjects. Pegylated interferon was the mainstay of treatment for HDV infection until bulevirtide, a viral entry inhibitor, was recently approved by the European Union (EMA) and FDA in America, while multiple novel therapies are already in clinical trials as part of the HBV cure program. Overall, awareness of chronic viral hepatitis in athletes should be improved. Prevention remains the cornerstone of the management of viral hepatitis in sport coupled with rigorous disease assessment in infected individuals, and antiviral therapy where indicated.

Neutralization of hepatitis B virus with vaccine-escape mutations by hepatitis B vaccine with large-HBs antigen

Although the current hepatitis B (HB) vaccine comprising small-HBs antigen (Ag) is potent and safe, attenuated prophylaxis against hepatitis B virus (HBV) with vaccine-escape mutations (VEMs) has been reported. We investigate an HB vaccine consisting of large-HBsAg that overcomes the shortcomings of the current HB vaccine. Yeast-derived large-HBsAg is immunized into rhesus macaques, and the neutralizing activities of the induced antibodies are compared with those of the current HB vaccine. Although the antibodies induced by the current HB vaccine cannot prevent HBV infection with VEMs, the large-HBsAg vaccine-induced antibodies neutralize those infections. The HBV genotypes that exhibited attenuated neutralization via these vaccines are different. Here, we show that the HB vaccine consisting of large-HBsAg is useful to compensate for the shortcomings of the current HB vaccine. The combined use of these HB vaccines may induce antibodies that can neutralize HBV strains with VEMs or multiple HBV genotypes.

The Investigation of Hepatitis B Vaccine Immune Responses in Occult Hepatitis B Virus-Infected Patients

Objectives

There is no effective treatment for occult hepatitis B virus infection (OBI) patients, and immunotherapy may be one of the most promising options. We aim to investigate the underlying mechanism and therapeutic potential of hepatitis B vaccine immunotherapy for OBI patients.

Methods

Outpatient OBI patients were screened and randomly divided into treatment (Group A) and control (Group B) groups. At weeks 0, 4, and 24, patients in Group A received a subcutaneous/intramuscular injection of hepatitis B vaccine (Engerix-B, 20 μg/time) according to the standard vaccination schedule; patients in Group B served as blank control. The patients were followed for 36 weeks, with clinical, biochemical, virological, immunological, and imaging data collected and analyzed at weeks 0, 12, 24, and 36, respectively, and the relation between the virology and immunology results was analyzed.

Results

Of the 228 OBI patients, 28 were excluded, and 200 were enrolled for observation. In the end, 44 patients were included in Group A and 39 in Group B after excluding lost cases. At week 0 (baseline), some patients in two groups had liver disease symptoms, HBV-related liver function damage, and liver fibrosis. 86.36% (38/44) and 82.05% (32/39) patients were positive for serum hepatitis B surface antibodies (anti-HBs) in Group A and Group B, respectively, with the median (quartile) of 42.47 (16.85, 109.1) and 39.27 (16.06, 117.4) mIU/ml, respectively. Reduced peripheral blood CD4⁺T, CD8⁺T, and B lymphocytes were found in some patients in two groups. These results were not statistically different between Group A and Group B (P>0.05). At week 36, all patients were serum anti-HBs (+) in Group A, with a median (quartile) of 1000 (483.9, 1000) mIU/ml, which was significantly higher than that at week 0 (P<0.05) and that in Group B (P<0.05). Compared to week 0, the number of CD8⁺ T and B lymphocytes increased significantly and were significantly higher than Group B at the same point. Two patients in Group B were found to have hepatitis B virus reactivation from week 12 to week 36.

Correlation Analysis

Anti-HBs in Group A patients were positively correlated with B lymphocytes (r=0.3431, 0.3087, and 0.3041, respectively) and positively correlated with CD8⁺ T lymphocytes (r=0.4954, 0.3054, and 0.3455, respectively) at weeks 12, 24, and 36.

Conclusion

Virological reactivation is a risk for OBI patients. Serum hepatitis B surface antibodies were significantly increased after hepatitis B vaccine treatment, the same as the numbers of peripheral blood B and CD8⁺ T lymphocytes; changes in hepatitis B surface antibody levels were positively correlated with the changes in peripheral blood B and CD8⁺ T lymphocytes.

Establishment of a monoclonal antibody against human NTCP that blocks HBV infection

Hepatitis B virus (HBV) infects 240 million people worldwide. Current therapy profoundly suppresses HBV replication but requires long-term maintenance therapy. Therefore, there is still a medical need for an efficient HBV cure. HBV enters host cells by binding via the preS1 domain of the viral L protein to the Na⁺/taurocholate cotransporting polypeptide (NTCP). Thus, NTCP should be a key target for the development of anti-HBV therapeutics. Indeed, myrcludex B, a synthetic form of the myristoylated preS1 peptide, effectively reduces HBV/hepatitis D virus (HDV) infection and has been approved as Hepcludex in Europe for the treatment of patients with chronic HDV infection. We established a monoclonal antibody (MAb), N6HB426-20, that recognizes the extracellular domain of human NTCP and blocks HBV entry in vitro into human liver cells but has much less of an inhibitory effect on bile acid uptake. In vivo, administration of the N6HB426-20 MAb prevented HBV viremia for an extended period of time after HBV inoculation in a mouse model system without strongly inhibiting bile acid absorption. Among the extracellular loops (ECLs) of NTCP, regions of amino acids (aa) 84 to 87 in ECL1 and aa 157 to 165 near ECL2 of transmembrane domain 5 are critically important for HBV/HDV infection. Epitope mapping and the three-dimensional (3D) model of the NTCP structure suggested that the N6HB426-20 MAb may recognize aa 276/277 at the tip of ECL4 and interfere with binding of HBV to the region from aa 84 to 87. In summary, we identified an in vivo neutralizing NTCP-targeting antibody capable of preventing HBV infection. Further improvements in efficacy of this drug will pave the way for its clinical applications.

IMPORTANCE A number of entry inhibitors are being developed to enhance the treatment of HBV patients with oral nucleoside/nucleotide analogues (NA). To amplify the effectiveness of NA therapy, several efforts have been made to develop therapeutic MAbs with neutralizing activity against HBs antigens. However, the neutralizing effect of these MAbs may be muted by a large excess of HBsAg-positive noninfectious particles in the blood of infected patients. The advantage of NTCP-targeted HBV entry inhibitors is that they remain effective regardless of viral genotype, viral mutations, and the presence of subviral particles. Although N6HB426-20 requires a higher dose than myrcludex to obtain equivalent suppression of HBV in a model mouse system, it maintained the inhibitory effect for a long time postadministration in proportion to the half-life of an IgG MAb. We believe that further improvements will make this antibody a promising treatment option for patients with chronic hepatitis B.

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.

Levels of hepatitis B antibody titers are affected by age and doses gap time in children from a high endemic area of the western Amazon

BACKGROUND

Despite completion of the vaccine schedule for hepatitis B virus (HBV), children may display levels of HBV surface antibodies (anti-HBs) that are considered inadequate for sufficient protection (<10 IU/L).

AIMS

Our aim was to investigate if age and gap time between HBV vaccine doses may negatively affect the levels of anti-HBs in children, and if these relationships are modified by sex.

METHODS

In a high-endemic HBV region of the western Brazilian Amazon we enrolled children who had completed the HBV vaccine schedule. All children underwent analysis of anti-HBs and a clinical examination.

RESULTS

We included 522 children (mean age 4.3 ± 0.8 years; 50% male). Median anti-HBs was 28.4 [interquartile range (IQR) 5.4 to 128.6] IU/L and 32% had anti-HBs <10 IU/L. The median gap time from last to preceding dose was 2.4 [IQR 2.1 to 3.3] months. Levels of anti-HBs decreased with higher age (-42% per year increase [95%CI -56% to -24%], p<0.001), but not with longer gap time (+23% per month increase [95%CI -16% to +62%], p = 0.249). After adjusting for relevant confounders, gap time became significant (p = 0.032) and age remained a significant predictor of anti-HBs (p<0.001).

CONCLUSION

One third of assessed children displayed anti-HBs <10 IU/L. Levels of anti-HBs decreased with higher age and increased with longer gap time between the last two doses.

Cross-Protection of Hepatitis B Vaccination among Different Genotypes

Hepatitis B (HB) vaccination is the most effective method for preventing HB virus (HBV) infection. Universal HB vaccination containing recombinant HB surface antigens (HBsAg) is recommended. Our data revealed that human monoclonal HB surface antibody (anti-HBs) from individuals inoculated with genotype C-based HB vaccine induced cross-protection against HBV genotype A infection. An in vitro infection model demonstrated anti-HBs-positive sera from individuals inoculated with genotype A- or C-based HB vaccine harbored polyclonal anti-HBs that could bind to non-vaccinated genotype HBV. However, because there were low titers of anti-HBs specific for HBsAg of non-vaccinated genotype, high anti-HBs titers would be required to prevent non-vaccinated genotype HBV infection. Clinically, the 2015 Centers for Disease Control and Prevention guidelines state that periodic monitoring of anti-HBs levels after routine HB vaccination is not needed and that booster doses of HB vaccine are not recommended. However, the American Red Cross suggests that HB-vaccine-induced immune memory might be limited; although HB vaccination can prevent clinical liver injury (hepatitis), subclinical HBV infections of non-vaccinated genotypes resulting in detectable HB core antibody could not be completely prevented. Therefore, monitoring anti-HBs levels after routine vaccination might be necessary for certain subjects in high-risk groups.

The Effect of the Hepatitis B Vaccine Derived from Genotype C on Infants Born to Mothers Infected with Genotype D

Objective There is a paucity of information on whether the hepatitis B virus (HBV) vaccine, derived from HBV genotype C, can prevent mother-to-child transmission of HBV genotype D. The aim of this study was to clarify this issue. Methods The subjects consisted of 25 children (8.5±4.1 years old, 7 males, 18 females), born to 17 mothers who were chronically infected with HBV genotype D. Of these, 20 children were inoculated with the genotype C-derived vaccine, one was inoculated with the genotype A-derived vaccine, and one was inoculated with both the A- and C-derived vaccines. Information on the type of vaccine given to the remaining three children was not available. The serum levels of HB surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to HB core (anti-HBc) of the children, as well as HBV markers of the mothers, were examined. Results All mothers were positive for HBsAg (6,563±11,005 IU/mL), negative for HBeAg, and positive for anti-HBe. HBV-DNA levels (log IU/mL) were <3.3 in 7 mothers, 3.3-4.3 in 9 mothers, and >4.3 in one mother. HBsAg and anti-HBc were negative in all children, regardless of the type of vaccine used. Anti-HBs were positive in 13 children and negative in 12. Conclusion All children born to mothers infected with genotype D, including 20 who were inoculated with the genotype C-derived vaccine, were negative for both HBsAg and anti-HBc. These results suggest that the genotype C-derived HB vaccine is effective in preventing mother-to-child transmission from mothers infected with HBV genotype D.

Comparison of hepatitis B vaccine efficacy in Japanese students: a retrospective study

Background

Two types of recombinant hepatitis B virus (HBV) vaccines are available in Japan. One type uses the antigen from genotype A (Heptavax-II®) and the other uses the antigen from genotype C (Bimmugen®). Potential differences in productivity of the hepatitis B virus surface (HBs) antibody between vaccines have not been studied in detail. We investigated the acquired level of immunity against HBV in association with two vaccines, their administration routes, and patient sex. We present the appropriate inoculation method based on the characteristics of each vaccine.

Methods

Data of 1135 medical and nursing students (481 men and 651 women) were used, each of whom was unvaccinated prior to recruitment and subsequently vaccinated three times prior to the study. The vaccine type and administration route differed according to the university department and enrolling year. The students were categorized into the following three groups: Bimmugen®-subcutaneous group, Heptavax-II®-subcutaneous group, and Heptavax-II®-intramuscular group. The total and sex-segregated positive rates of the HBs antibody among the three groups were compared using Pearson’s chi-square test. The effect of time between the HBs antibody test and vaccine administration on the HBs antibody level was also analyzed similarly.

Results

The Bimmugen®-subcutaneous group showed the highest positive HBs antibody rate (92.0%) among the three groups. In the Heptavax-II® group, the positive rate was 66.3% in the subcutaneous injection group and 89.1% in the intramuscular injection group. There was a significant difference among these three groups. In terms of sex, women showed a significantly higher average positive rate than men in each group. In terms of effect of time between the HBs antibody test and vaccine administration, no significant differences were observed.

Conclusions

Bimmugen® is associated with more effective HBs antibody production than Heptavax-II® in Japanese students. However, the Heptavax-II® vaccine is an appropriate choice for HBV vaccination in areas where HB is caused predominantly by HBV genotype C. With both vaccines, women tended to acquire more immunogenicity than men. Intramuscular injection may be the preferred administration route due to the possibility of local reactions.

Optimal titer of anti-HBs in blood components derived from donors with anti-HBc

BACKGROUND

The ultimate strategy to cope with transfusion-transmitted hepatitis B virus (HBV) infection caused by transfusion of blood from donors with historical HBV infection is to reject all donors having anti-HBV core antigen (anti-HBc). However, this strategy would result in a huge loss of blood donors and subsequent blood inventory collapse. On the other hand, anti-HBc-positive blood is reportedly not infectious when containing more than 100 mIU/mL of anti-HBV surface antigen (anti-HBs).

STUDY DESIGN AND METHODS

In Japan, anti-HBc-positive blood has been used for transfusion if it contained 200 mIU/mL or more of anti-HBs. First, to verify the screening policy, clinical outcomes for transfusion of such blood were analyzed for the 2008-2012 period. Second, human hepatocyte-repopulated severe combined immunodeficiency mice were inoculated with HBV preincubated with varying doses of anti-HBs, then viremic status was followed. The effects of anti-HBs across different HBV genotypes were also investigated.

RESULTS

Twenty-three transfusion-transmitted HBV infections related to anti-HBc-positive blood components were identified. None of the blood responsible for these cases contained 200 mIU/mL or more of anti-HBs. When 100 μL of plasma containing 10⁴ copies of HBV and 20 mIU of anti-HBs was injected into severe combined immunodeficiency mice, no viremia was detected within 13 weeks. Genotype C anti-HBs was capable of total inhibition of genotype A HBV replication, whereas genotype A anti-HBs inhibited genotype C HBV to a lesser extent.

CONCLUSION

Anti-HBc-positive blood containing 200 mIU/mL or more of anti-HBs appears safe as a transfusion component. HBV vaccination seems effective between HBV genotypes A and C.

Progress and challenges for the Japanese immunization program: Beyond the "vaccine gap"

The Japanese immunization program has made considerable recent progress. The introduction of several new vaccines, especially foreign-produced vaccines, and the inclusion of important new vaccines in the National Immunization Program (NIP) are closing the "vaccine gap", i.e., the delay in the Japanese immunization program relative to programs in other developed countries. Major progress in the Japanese immunization program since 2014 includes (1) elimination of measles in March 2015, (2) introduction of a varicella vaccine as a routine immunization in the NIP in October 2015, and (3) introduction of hepatitis B virus vaccines as routine immunizations in the NIP in October 2016. Despite these promising developments, important issues remain. First, the government withdrew the active recommendation for human papilloma virus vaccines temporarily in 2013. The withdrawal has continued and unresolved despite new scientific evidence confirming the safety of these vaccines. Second, a few important voluntary vaccines, including vaccines for mumps and rotavirus, have not been included in the NIP since their introduction to Japan. Finally, there are concerns related to a shortage of mandatory domestic vaccines, which was caused by a natural disaster in the area where a vaccine-producing factory was located. Additionally, the manufacturer included unauthorized additives in some vaccine products with falsifying the production-process records. To avoid problems related to vaccine shortages, essential vaccines need to be stockpiled, and the future vaccine needs for children should to be discussed. New initiatives must continue to close the vaccine gap, as this will protect children living in Japan from vaccine-preventable diseases.