Hepatitis B vaccines

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.

Adherence and Effectiveness of HBV Vaccination among Healthcare Workers in Egypt

Context:

Healthcare workers (HCWs) face a potential risk of acquiring different bloodborne pathogens, by occupational exposure to contaminated blood and body fluids. Hepatitis B vaccine is a safe, effective method of conferring long-term protection against HBV infection.

Aims:

The study aimed to assess the adherence and effectiveness of HBV vaccination among HCWs at Gastrointestinal Surgical Center, Mansoura University, Egypt.

Settings and Design:

A prospective descriptive study was carried out between June 2019 and December 2019 at Gastrointestinal Surgical Center, Mansoura University, Egypt.

Methods and Material:

All HCWs with anti-HBs levels below 10 mIU/mL were advised to receive 3 doses of recombinant HBV vaccine, at 0, 1, and 6 months. The anti-HBs levels were checked 3 months after the third dose of the HBV vaccine.

Statistical Analysis Used:

Data was analyzed using the Statistical Package of Social Science (SPSS) program for windows (version 16).

Results:

A total of 442 healthcare providers were included. Most of them completed the 3 doses of the vaccine (81.7%), 10.2% refused the vaccine, while 0.9% and 7.2% received 1 and 2 doses, respectively. Odds of vaccination were the highest (88.1%, 273/310) among nurses (OR, 4.7; 95% CI, 2.6–5.2; P ≤ 0.001). The overall anti-HBs positivity of 97% (350/361) was observed. The main reasons for not being vaccinated included the fear of vaccine side effects 25/81 (30.9%) and lack of trust in the vaccine effectiveness 18/81 (22.2%).

Conclusions:

The outcome of the present study emphasizes the need to apply alternative and innovative measures to build a positive attitude toward the HBV vaccine among HCWs.

The Prevalence of Hepatitis B Virus Markers among Students of Shiraz University of Medical Sciences

Background

Protection against hepatitis B virus (HBV) is based on the presence of antibodies against hepatitis B surface antigen (HBsAg). Vaccination of newborns is the most effective means of prevention. This study aimed to evaluate the frequency of anti-HBs antibody (anti-HBsAb), anti-HB core Ab (anti-HBcAb), HBsAg, and HBV DNA among university students in Fars province, Southern Iran.

Materials and Methods

In this cross-sectional study, 272 students of Shiraz University of Medical Sciences, were enrolled. Venous blood (5 mL) was collected from each participant and centrifuged; the sera were stored at -20°C until use. Anti-HBsAb, Anti-HBcAb, and HBsAg were measured using a commercial enzyme-linked immunosorbent assay kit. HBV DNA load was also measured by a real-time polymerase chain reaction.

Results

The mean age of the participants was 19 ± 1 years. There were 171 (62.9%) females and 101 (37.1%) males. Anti-HBsAb at a protective level (>10 mIU/mL) were detected in the sera of 104 (38.5%) of the cases. Of the anti-HBsAb seropositive participants, 82 were female and 22 were male; the difference between the gender and seropositivity to anti-HBsAb was statistically significant (P = 0.001, odds ratio: 3.3, 95% confidence interval = 1.89-5.79). Anti-HBcAb was detected in only one participant that was negative for both HBsAg and HBV DNA.

Conclusion

Findings of the current study show that more than half of the students do not have a protective level of anti-HBsAb and might be susceptible to HBV infection, indicating the necessity of checking the level of anti-HBsAb as well as a booster dose in high-risk groups.

Post-exposure treatment with whole inactivated H5N1 avian influenza virus protects against lethal homologous virus infection in mice

Concerns with H5N1 influenza viruses include their prevalence in wild and domestic poultry, high mortality rate (~60%) in humans with some strains, lack of pre-existing immunity in humans, and the possibility that these viruses acquire mutations that enable efficient transmission between humans. H5 subtype viruses of Eurasian origin have recently appeared in wild and domestic bird populations in North America, and have led to the generation of new virus strains that are highly pathogenic in poultry. These new H5 HA containing viruses with their ability to evolve rapidly represent an unknown threat to humans in contact with infected poultry, and vaccination with an off-the-shelf vaccine may be impractical to provide protection to at-risk individuals. Instead, we have evaluated the efficacy of a formalin-inactivated vaccine, which could be derived directly from a circulating virus, to provide post-exposure protection. This strategy was evaluated using a prototypic highly pathogenic avian H5N1 strain, A/Vietnam/1203/2004, and demonstrated rapid induction of adaptive immune responses providing protection in a mammalian model of lethal infection. Additionally, this post-exposure vaccine was highly efficacious when administered 24 hours after exposure. This study offers a platform for developing effective post-exposure vaccines for treatment of highly virulent influenza infections.

Immunogenicity of Recombinant Hepatitis B Vaccine Among Routinely Vaccinated Healthy and Chronically Ill Children in Assiut, Upper Egypt

BACKGROUND

Egypt is considered a region of the intermediate prevalence of hepatitis B virus (HBV) infection (4.5%). Seroprotection is assured when hepatitis B surface antibody (HBsAb) levels are ≥ 10 mIU/mL. Our study aimed to evaluate and compare the long-term immunogenicity and efficacy of the recombinant hepatitis B (HB) vaccine.

METHODS

A cross-sectional study was done for children aged from 9 months to 15 years, receiving health care at Assiut University Children's Hospital, Assiut, Egypt in 3 months. HBsAb was quantitatively determined by enzyme-linked immune sorbent assay (ELISA).

RESULTS

Seroprotection in infants less than 1 year was 89.7% with 55.2% having titer > 100 mIU/mL and this percent dropped to 64.4% after the first year of age with only 29% having titer > 100 mIU/mL. The overall protection percentage was 32.5% (> 100 mIU/mL), 34.7% of children showed levels between 10 and 100 mIU/mL, while 32.8% were less than 10 mIU/mL. Patients with diabetes mellitus were found to have the lowest seroprotective levels (83.3% were not protected). Non-protective levels were also detected in patients with malnutrition (55.6%), congenital heart diseases (43.2%) and chronic liver diseases (57.1%).

CONCLUSION

Our study shows failure to achieve satisfactory seroprotective levels for hepatitis B vaccine in both healthy and diseased children who adopted vaccination schedule in Upper Egypt. Booster dose in the second year of life is recommended for all children, particularly for those with diabetes millets, congenital heart disease and malnutrition.

Two-phase fed-batch modification for 48 hour peak expression of hepatitis B surface antigen in Pichia pastoris shake flask system

A study of the Mut+ phenotype for the expression of recombinant hepatitis B surface antigen (HBsAg) in Pichia pastoris strain GS115 using the pPIC3.5K vector with a two-phase fed-batch protocol in a shake flask system is described. Expression levels of HBsAg protein of 6.74 g L−1 Dry Cell Weight (DCW) and 26.07 mg L−1 of HBsAg concentration were achieved 48 h from the induction point which added to a 120 h reduction in production period in comparison with MutS expression (168 h). The use of the pPIC3.5K-HBsAg plasmid in the Mut+ phenotype enhanced the expression of HBsAg by a nearly 13 times higher volumetric productivity in the first 24 h and 35 times higher at peak production concentration. Comparison of AOX expression cassettes relative to the HBsAg gene in the role of mRNA secondary structure during translation initiation revealed that HBsAg possesses lower folding stability with AOX1 Mut+ phenotype. The results from this study demonstrated that expression of HBsAg with Mut+ AOX1 promoter is adequate as an alternative for the production of HBsAg. In addition, the AOX promoter of the Mut+ phenotype was observed to be better suited for HBsAg expression, which correlates with the ease of translation initiation under shake flask conditions.

Hemodialysis and hepatitis B vaccination: a challenge to physicians

Hepatitis B is responsible for the development of half of hepatocellular carcinoma cases and is a major cause of hepatic insufficiency. The vaccine against hepatitis B virus does not exhibit the same high efficacy in patients on hemodialysis as it does in immunocompetent individuals. The medical literature recommends vaccination with four doses (40 mg each) of the hepatitis B virus vaccine before beginning hemodialysis; however, approximately one-third of hemodialysis patients do not respond to this vaccination schedule. A new serologic test should be performed each year for individuals who respond adequately, whereas a booster dose should be offered to those with antibody titers below 10 mIU/mL. In this study, we followed 83 hemodialysis patients and collected quantitative serologic measurements every 2 months over a 1-year period. We made the measurements 1 month after the vaccination period. We found that 41% of the patients had antibody titers below 10 mIU/mL (nonresponders), 21.7% had antibody titers between 10 mIU/mL and 100 mIU/mL (poor responders), and 37.3% had antibody titers higher than 100 mIU/mL (good responders). Patients with diabetes and/or hypertension exhibited worse response to vaccination. All subjects displayed decreasing antibody titers during the observation period. The group of poorly responsive patients had antibody titers below 10 mIU/mL at the 6-month follow-up period.

IFNG and IFNGR1 gene polymorphisms in children with nonresponse to the hepatitis B vaccine

ABSTRACT: 

Aim: We investigated the +874 T/A polymorphism in the first intron of the IFNG gene and intronic (CA)n polymorphic microsatellite marker of the IFNGR 1 gene in child nonresponders to hepatitis B vaccination. Materials & methods: A total of 100 children who had anti-HBs antibody levels <10 mIU/ml after vaccination against hepatitis B were included as a nonresponder group and 100 children who had anti-HBs antibody levels >10 mIU/ml after vaccination against hepatitis B were included as a responder group. Results: The frequency of the TT genotype of the IFNG (+874 T/A) gene polymorphism was higher in nonresponders (p = 0.003). The frequencies of alleles 170 and 182 for (CA)n alleles for the intronic (CA)n microsatellite of IFNGR1 were significantly higher in nonresponders (for each, p < 0.05). Conclusion: The TT genotype of the IFNG (+874 T/A) gene, and alleles 170 and 182 for (CA)n alleles for the intronic (CA)n microsatellite of the IFNGR1 gene, may be associated with nonresponse to hepatitis B vaccination.

The immunogenicity of a single dose of hepatitis A virus vaccines (Havrix® and Epaxal®) in Korean young adults

PURPOSE

Assessing the immunogenicity of a single dose of hepatitis A virus (HAV) vaccines is important because some people receive only a single dose. However, previous studies have shown variable results and have not examined the effects of demographic characteristics other than gender. This study was performed to examine the immunogenicity of a single dose of HAV vaccine according to the vaccine type and demographic characteristics in young adults.

MATERIALS AND METHODS

Seronegative medical school students were randomly allocated to receive either Havrix or Epaxal.

RESULTS

After approximately 11 months, the seroconversion rate in 451 participants was 80.7%. In men, the Havrix group showed a significantly higher seroconversion rate (81.9%) than the Epaxal group (69.2%), whereas both vaccine groups showed similarly high immunogenicity in women (Havrix: 90.1%, Epaxal: 92.9%; P for interaction=0.062). According to the results of a multivariate analysis, Epaxal showed significantly lower immunogenicity than Havrix only in men. Age, obesity, drinking, smoking, and follow-up time did not significantly affect seroconversion in either gender.

CONCLUSION

The seroconversion rate of single-dose HAV vaccines was low in men, particularly in those who received Epaxal. Our results suggest that gender effects should be considered when comparing the immunogenicity of different HAV vaccines.

Role of gluten intake at the time of hepatitis B virus vaccination in the immune response of celiac patients

Some reports have demonstrated an inadequate response to hepatitis B vaccination in patients affected by celiac disease. The aim of our study was to evaluate hepatitis B vaccination response in relation to gluten exposure status in patients with celiac disease. To measure the gluten exposure status at the time of vaccination, we considered three groups: group A (exposed to gluten), including patients vaccinated as 12-year-old adolescents (the celiac disease diagnosis was established after vaccination); group B (not exposed to gluten), including patients vaccinated as 12-year-old adolescents on a gluten-free diet at the time of vaccination; and group C (infants), including patients vaccinated at birth. The response of celiac patients to hepatitis B vaccination was compared to that of healthy subjects, i.e., those in the control group (group D). This study included 163 celiac patients (group A, 57 patients; group B, 46 patients; and group C, 60 patients) and 48 controls (group D). An inadequate response to hepatitis B immunization was present in 43.9% of patients in group A, 34.8% of patients in group B, 58.3% of patients in group C, and 8.3% of patients in group D (group A versus group D, P < 0.001; group B versus group D, P = 0.002; group C versus group D, P = 0.001) (no significant difference for group A versus group B and group A versus group C was evident). Our data suggest that gluten exposure does not influence the response to hepatitis B immunization and that the human leukocyte antigen probably plays the main immunological role in poor responses to hepatitis B-vaccinated celiac patients.

Revaccination of non- and low- responders after a standard three dose hepatitis B vaccine schedule

BACKGROUND

Guangdong province of China is HBV high endemicity and 1.6 million neonates are administrated 5 μg yeast recombinant anti-HBV vaccine each year. But few studies are performed to evaluate the immunogenicity and revaccination effect on non- and low- responders.

METHODS

2,199 children were administered intramuscularly with 5 μg vaccine at 0, 1 and 6 mo after birth. A 3 ml blood sample was drawn from each infant 1 mo after the third dose for determination of anti-HBs level. Three additional doses (10 μg each) were given to non- and low- responders.

RESULTS

Of 1,814 subjects, 3.1% were non-responders (anti-HBs titer < 10 mIUml (-1) ) and 28.9% were low-responders (anti-HBs ≥ 10 mIUml (-1) and < 100 mIUml (-1) ). Low birth weight (LBW) was a risk factor for non- and low- responders (RR = 1.6, 95%CI = 1.2-2.0). After revaccination, of the 34 non-responders, 14.7% became low-responders and 85.3% became responders. Of the 74 low-responders, 21.6% remained at the same level and 78.4% shifted into responder category.

CONCLUSIONS

Based on the lower responding rate after the primary immunization cycle and the higher responding rate after the additional cycle, measurement of anti-HBs level should be considered for people who had been immunized with three-dose 5 μg HB vaccine in Guangdong, especially for specific populations including LBW infants, healthcare workers, and patients with immunodeficiency disorders. An amount of 10 μg vaccine should be revaccinated to any non- and low- responders to provide adequate seroprotection.

Hepatitis A and hepatitis B vaccination responses in persons with chronic hepatitis C infections: A review of the evidence and current recommendations

In persons with chronic hepatitis C virus (HCV) infections, superinfection by hepatitis A virus (HAV) or hepatitis B virus (HBV) can cause serious complications, including fulminating hepatitis or increased severity of hepatitis. Therefore, it is important to adequately protect persons with chronic HCV infections by immunization. Suboptimal response to vaccines has been reported in patients with chronic liver disease. The present article reviews HAV and HBV vaccine responses reported in the literature when administered to individuals with chronic HCV infection, and reviews current national and international recommendations.

RESULTS

Persons with chronic HCV respond well to HAV vaccine, but studies exploring HBV vaccine efficacy in this population have equivocal results. Vaccine schedules and participant characteristics differ among studies, and most do not adjust for confounders. Some studies found no difference in HBV vaccine response between patients with chronic HCV and controls. However, HBV vaccine response was generally reduced in those with cirrhosis and HCV genotype 1. Organizations recommend HAV and HBV vaccines for persons with chronic HCV, but do not suggest alterations in schedule or dose.

RECOMMENDATIONS

Because HAV vaccine response is good and routine laboratory testing may not detect lower levels of vaccine-induced anti-HAV, the standard HAV vaccine schedule is recommended without postimmunization testing. HBV vaccine should be administered early in the course of chronic HCV infection because response may be lower in patients with cirrhosis. Reflex testing of anti-HCV reactive sera for anti-HAV and hepatitis B surface antibody can facilitate appropriate follow-up and timely immunization. Determination of postimmunization hepatitis B surface antibody, especially in patients with cirrhosis or genotype 1, will allow HBV vaccine boosters to be offered.

Comparison of a bacteriophage-delivered DNA vaccine and a commercially available recombinant protein vaccine against hepatitis B

A bacteriophage lambda DNA vaccine expressing the small surface antigen (HBsAg) of hepatitis B was compared with Engerix B, a commercially available vaccine based on the homologous recombinant protein (r-HBsAg). Rabbits (five per group) were vaccinated intramuscularly at weeks 0, 5 and 10. Antibody responses against r-HBsAg were measured by indirect enzyme-linked immunosorbent assay, by limiting dilutions and by subtyping. Specific lymphocyte proliferation in vitro was also measured. After one vaccination, three of the five phage-vaccinated rabbits showed a strong antibody response, whereas no r-HBsAg-vaccinated animals responded. Following two vaccinations, all phage-vaccinated animals responded and antibody levels remained high throughout the experiment (220 days total). By 2 weeks after the second vaccination, antibody responses were significantly higher (P<0.05) in the phage-vaccinated group in all tests. After three vaccinations, one out of five r-HBsAg-vaccinated rabbit still failed to respond. The recognized correlate of protection against hepatitis B infection is an antibody response against the HBsAg antigen. When combined with the fact that phage vaccines are potentially cheap to produce and stable at a range of temperatures, the results presented here suggest that further studies into the use of phage vaccination against hepatitis B are warranted.

Barriers to hepatitis B vaccine coverage among healthcare workers in the Republic of Georgia: An international perspective

BACKGROUND

While the Republic of Georgia has a high prevalence of hepatitis B virus (HBV) infection (3.4% of blood donors tested positive for HBV surface antigen [HBsAg]), relatively few healthcare workers (HCWs) are thought to be immunized.

OBJECTIVE

To measure rates of HBV vaccination coverage and identify predictors of vaccine acceptance among HCWs.

DESIGN

Cross-sectional survey.

METHODS

A study was conducted among full-time physicians and nurses at 2 large hospitals. Self-administered questionnaires included questions about demographic characteristics, HBV vaccine status, willingness to recommend vaccination to other HCWs, and barriers to vaccination. Laboratory tests were conducted for identification of HBsAg and antibody to hepatitis B core antigen.

RESULTS

A total of 297 (91%) of 325 randomly selected HCWs provided information for the study (124 physicians and 173 nurses). The rate of HBV vaccination coverage was 12%, and 54% of respondents indicated that they would recommend vaccination to other HCWs. Perception of vaccine safety was identified as the most important predictor for acceptance (prevalence ratio [PR], 3.3 [95% confidence ratio {CI}, 1.2-8.9]) and for willingness to recommend HBV vaccination to other HCWs (PR, 5.5 [95% CI, 3.1-9.4]). Vaccinated HCWs were more likely to recommend vaccination to other healthcare personnel (PR, 1.7 [95% CI, 1.5-2.1]), as were those younger than 40 years of age (PR, 6.0 [95% CI, 2.8-12.6]). Multivariate analyses identified 2 additional factors associated with vaccine acceptance and willingness to recommend vaccination: the hospital at which the HCW was employed and the perception of risk of infection for HCWs.

CONCLUSION

Georgia plans a major HBV vaccination campaign for HCWs in 2009. The campaign's success will depend on addressing vaccine safety concerns identified in this study and educating HCWs about risk factors for infection and benefits of immunization.

Intramuscular immunization with a vesicular stomatitis virus recombinant expressing the influenza hemagglutinin provides post-exposure protection against lethal influenza challenge

Vaccines currently licensed for the prevention of seasonal influenza induce antibodies against the influenza hemagglutinin (HA) and neuraminidase (NA) contained in the vaccine preparation but require at least 2 weeks after immunization for the development of protective immunity. These vaccines do not induce protective responses quickly enough to blunt the effects of infection when administered after exposure. We have developed a novel vaccine based on recombinant vesicular stomatitis virus which expresses the influenza hemagglutinin (rVSV HA) and protects mice from lethal influenza challenge when the vaccine is administered intramuscularly at least 24h after delivery of the influenza challenge virus. To our knowledge this is the first vaccine that effectively protects animals from lethal influenza challenge when delivered by a systemic route after influenza exposure has occurred. The induction of HA-specific immune responses by the vaccine is necessary for full protection from challenge, because animals immunized with an empty rVSV vector were not protected equally. Our results are consistent with a model in which vaccination induces an immediate antiviral cytokine response, followed by development of humoral and cellular immune responses which act to reduce pulmonary viral loads and accelerate recovery. Consistent with this model, mice vaccinated with the specific vaccine rVSV HA had high levels of IFN-alpha in the serum by 24h after challenge/vaccination, developed serum neutralizing Ab to influenza 2 days prior to control animals, and had detectable anti-HA CD8 T cells present in the peripheral blood 3 days prior to control mice.

Hepatitis B immunity in adolescents and necessity for boost vaccination: 23 years after nationwide hepatitis B virus vaccination program in Taiwan

The first universal hepatitis B vaccination program for newborns in the world was launched in Taiwan in July 1984. Most studies on the effectiveness of hepatitis B vaccination focused on the seroprevalence of HBs Ag among children under 14 years old. Only few studies focused on the seropositivity of anti-HBs among adolescents aged 15-18 years old. The present study aimed to evaluate the impact of the nationwide hepatitis B vaccination program on the immunity to HBV infection and the necessity of boost among adolescents. In this study including eight annual seroprevalence surveys from 2000 to 2007, 2342 college entrants (1589 15-year-olds in group I and 753 18-year-olds in group II) and 1851 university freshmen (18-year-olds in group III) participated. Subjects identified anti-HBs, HBs Ag and anti-HBc negative were given boost three doses of HBV vaccine. The HBs Ag seroprevalence was 11.6%, 3.5% and 1.0% for participants who were born before 1984, 1984-1986 and after 1986. The anti-HBs-seropositive rates were significantly higher in group II (83.1%) than in group I (53.0%) and group III (53.5%). All 572 participants who were seronegative for anti-HBs, HBs Ag and anti-HBc became anti-HBs-seropositive after catch-up vaccination. It is concluded that the anti-HBs-seropositive rate decreased to 50% in 15 years after vaccination, and boost vaccination was 100% effective. The necessity and age for boost among anti-HBs negative adolescents and the timing of the first immunization should be further evaluated.

Immunopathogenesis of hepatitis B persistent infection: implications for immunotherapeutic strategies

It has been shown that cellular immunity, especially by cytotoxic T lymphocytes (CTLs), NK cells and NK-T cells, plays a central role in the control of virus infection. In addition, CD4+ T cells facilitate both CTL and B-cell responses. Hyporesponsiveness of HBV-specific T cells in peripheral blood has been shown in patients with chronic HBV infection. Interferon and nucleos(t)ide analogs, such as lamivudine, adefovir, entecavir and tenofovir, are the currently available treatments. Unfortunately, the efficacy of nucleos(t)ide analogs is limited by viral reactivation by the emergence of escaped mutants in cases of prolonged treatment. Therefore, immunotherapy is one of the significant options to eradicate or control HBV replication without drugs. The aim of immunotherapies is to decrease the levels of viral replication and to eradicate infected hepatocytes. For this reason, new strategies for immunotherapies by vaccination target not only the induction or stimulation of CD4+ and CD8+ T cell responses, but also the induction of proinflammatory cytokines capable of controlling viral replication. We will review the immunopathogenesis of persistent HBV infection, especially focusing on the mechanisms of immune suppression. Then we will review the immunotherapy for HBV persistent infection.

Production of surface plasmon resonance based assay kit for hepatitis diagnosis

Hepatitis B surface antibody (HBsAb) imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-L-tyrosine methyl ester) (PHEMAT) film on the surface plasmon resonance (SPR) sensor chip was prepared for diagnosis of HBsAb in human serum. Gold SPR chip surface was modified with allyl mercaptane and, then, HBsAb-imprinted PHEMAT film was formed on the chip surface. Surface characterization of the non-modified, allyl mercaptane modified and HBsAb-imprinted PHEMAT SPR chips were investigated with contact angle, atomic force microscopy (AFM). Kinetic studies were performed using HBsAb positive human serum. In order to determine the kinetic and binding constants, Scatchard, Langmuir, Freundlich and Langmuir-Freundlich models were applied to experimental data. Scatchard curve shows that HBsAb imprinted SPR chip has some surface heterogeneity, SPR chip obeyed the Langmuir adsorption model. The maximum detection limit was 208.2 mIU/mL. K(A) and K(D) values are 0.015 mIU/mL and 66.0 mL/mIU, respectively. Control experiments of the SPR chip were performed using non-immunized, HBsAb negative serum. The control experiment results show that SPR chip does not give any noticeable response to HBsAb negative serum.

[Vaccinations of HIV-infected travelers]

Human immunodeficiency virus (HIV) positive international travelers are at higher risk of infectious complications. The pretravel assessment often provides an opportunity to update routine vaccinations and HIV patient specific vaccinations including pneumococcus, hepatitis A, hepatitis B, and influenza. Other vaccinations may be required or recommended. Decision for vaccination require considering the risk and severity of the vaccine, preventable diseases in the destination area, the nature of the vaccine (live attenuated vaccines or not), the patient's immune status, and the risk of virological rebound as a consequence of vaccination. The immunogenicity of vaccines is decreased in HIV patient with low CD4 cell counts (above 500 cells per cubic millimetres and particularly above 200 cells per cubic millimetres) and in patients with a persistent HIV RNA viral load. Vaccines should be administered to patients whose HIV infections are in the early stage or in patients receiving HAART with a satisfactory immune status and reduced HIV RNA level. Testing of postvaccination antibodies is useful if serological protective levels are defined. In case of non-response after vaccination, few studies suggest that additional revaccination, increase of vaccine dose, intradermic vaccination, or use of prime-boost combination may be successful. Further research is needed to define vaccination strategies, adapted to the immune status of the HIV patient.

Expression of hepatitis B surface antigen major subtypes in Pichia pastoris and purification for in vitro diagnosis

This study describes the expression in Pichia pastoris of hepatitis B surface antigens (HBsAg) corresponding to the S region of the four major subtypes: adr, adw2, ayr and ayw3 and to the preS2-S region of the two subtypes adr and adw2. The recombinant yeast strains have been selected amongst methanol utilization positive (Mut+) or sensitive strains (Mut s) and cultivated to high cell density in bioreactor using a short protocol. Our results prove the efficiency of P. pastoris to produce all the major HBsAg subtypes and confirm the ability of the methanol regulated promoter of alcohol oxidase I gene (AOX) to express heterologous protein through phenotype Mut+ or Mut s strains. All these recombinant HBsAg proteins, including subtype ayr, whose production has never been presented, have been highly purified using a short original sequence of steps which includes high-pressure cell disruption associated with detergent treatment, ultrafiltration and immunopurification chromatography using a mAb anti-HBs. The whole process avoids possible alterations of antigenic properties and allows to obtain with high yield, high quality reagents for in vitro diagnosis.

Effective post-exposure treatment of Ebola infection

Ebola viruses are highly lethal human pathogens that have received considerable attention in recent years due to an increasing re-emergence in Central Africa and a potential for use as a biological weapon. There is no vaccine or treatment licensed for human use. In the past, however, important advances have been made in developing preventive vaccines that are protective in animal models. In this regard, we showed that a single injection of a live-attenuated recombinant vesicular stomatitis virus vector expressing the Ebola virus glycoprotein completely protected rodents and nonhuman primates from lethal Ebola challenge. In contrast, progress in developing therapeutic interventions against Ebola virus infections has been much slower and there is clearly an urgent need to develop effective post-exposure strategies to respond to future outbreaks and acts of bioterrorism, as well as to treat laboratory exposures. Here we tested the efficacy of the vesicular stomatitis virus-based Ebola vaccine vector in post-exposure treatment in three relevant animal models. In the guinea pig and mouse models it was possible to protect 50% and 100% of the animals, respectively, following treatment as late as 24 h after lethal challenge. More important, four out of eight rhesus macaques were protected if treated 20 to 30 min following an otherwise uniformly lethal infection. Currently, this approach provides the most effective post-exposure treatment strategy for Ebola infections and is particularly suited for use in accidentally exposed individuals and in the control of secondary transmission during naturally occurring outbreaks or deliberate release.

Being highly pathogenic for humans and monkeys and the subject of former weapons programs makes Ebola virus one of the most feared pathogens worldwide today. Due to a lack of licensed pre- and post-exposure intervention, our current response depends on rapid diagnostics, proper isolation procedures, and supportive care of case patients. Consequently, the development of more specific countermeasures is of high priority for the preparedness of many nations. In this study, we investigated an attenuated vesicular stomatitis virus expressing the Ebola virus surface glycoprotein, which had previously demonstrated convincing efficacy as a vaccine against Ebola infections in rodents and monkeys, for its potential use in the treatment of an Ebola virus infection. Surprisingly, treatment of guinea pigs and mice as late as 24 h after lethal Ebola virus infection resulted in 50% and 100% survival, respectively. More important, 50% of rhesus macaques (4/8) were protected if treated 20 to 30 min after Ebola virus infection. Currently, this approach provides the most effective treatment strategy for Ebola infections and seems particularly suited for the use in accidental exposures and the control of human-to-human transmission during outbreaks.

Antibody titer in Iranian children 6 years after hepatitis B vaccine administration

OBJECTIVE

The purpose of study was to evaluate the immune response in a sample of vaccinated children aged 6 years.

BACKGROUND

Although immunization of infants against hepatitis B virus (HBV) is the most effective way to prevent infection, duration of the afforded immunization is unknown.

METHODS

The immunity derived from the HBV vaccine was assessed by measuring the antibody in 3752 children who were vaccinated in a routine vaccination program in three cities of Iran (Isfahan, Khoramabad, Shahrekord).

RESULTS

Seven hundred and twenty-three (19.3%) children had antibodies levels <10 MIU/mL and 1096 (29.2%) had antibodies levels >or=100 MIU/mL. The total GMT was 34.5+/-0.66, and GMT was statistically different in non-immune and immune children (3.1+/-0.36 versus 49.1+/-0.52). No correlation was found between HbsAb titers and growth pattern during the first and sixth years of life, number of vaccine, time of vaccination and drug use. The predictors were low birth weight and chronic disease.

CONCLUSION

It is recommended that high risk children should be monitored regularly for anti-HBS, and booster must be administrated, if necessary.

Hepatitis B vaccination in women healthcare workers: a seroepidemiological survey

OBJECTIVE

To assess the concentration and kinetics of antibody response after hepatitis B vaccination among women healthcare workers.

DESIGN

Longitudinal retrospective seroepidemiological survey among women vaccinated against hepatitis B working in a university hospital and followed-up in an occupational health department. A structured form was used to collect socio-demographic characteristics, clinical data, age at vaccination, vaccination schedule, measurement of antibodies to hepatitis B surface antigen (anti-HBs antibody). Subjects were considered seronegative against hepatitis B when anti-HBs antibody concentration was less than 10 mIU/ml.

SETTING

A 1260-bed general hospital in Paris, France.

PARTICIPANTS

All women healthcare workers visiting the occupational health department between January 1997 1st and December 2000 31st and who had a measurement of anti-HBs antibody.

RESULTS

Irrespective of the age at the primary vaccination, 810 (92%) women were seropositive (anti-HBs antibody > or = 10 mIU/ml). Only 22 women (4.5%) vaccinated before 26 years of age were seronegative, against 46 (13.2%) vaccinated after 25 years of age (p < 0.001). Seven years after vaccination, 78% of women were still seropositive. An inadequate vaccination schedule (adjusted hazard ratio (HR), 3.0; 95% confidence interval [CI], 1.6-5.5) and an age greater than 25 years at primary vaccination (HR, 2.6; 95% CI, 1.5-4.4) were associated with being seronegative against hepatitis B.

CONCLUSIONS

Despite vaccination, some women healthcare workers were seronegative against hepatitis B virus. Vaccinating early in the career of a health-care worker using an adequate schedule seems key-elements to guarantee an anti-HBs measurement > or =10 mIU/ml.

Patients with inflammatory bowel disease are at risk for vaccine-preventable illnesses

BACKGROUND

Patients with chronic, immune-mediated conditions such as inflammatory bowel disease (IBD) are often treated with long-term immunosuppressive therapies, potentially increasing their risk of developing an infection. Empiric data suggest that vaccines are underutilized in immunocompromised patients, despite published guidelines recommending their use. We aimed to assess exposure risk and immunization status among patients receiving care in an IBD specialty clinic.

METHODS

Patients completed a self-administered, pretested, structured questionnaire during a routine visit for the management of IBD. Survey questions related to medical and immunization histories, and exposures to known risk factors for influenza, pneumococcus, viral hepatitis, and varicella. Additionally, in a subgroup of patients who agreed to donate a sample of blood, immune status to hepatitis A (HAV), hepatitis B (HBV), and varicella was determined.

RESULTS

Two hundred four patients were asked to participate in the study; 169 completed surveys and comprised the study population. Mean age was 35 yr (range 13-75 yr). One hundred forty-six respondents (86%) reported current or prior use of immunosuppressive medications. Only 45% of respondents recalled tetanus immunization within the past 10 yr, 41 (28%) reported regularly receiving flu shots, and 13 (9%) reported having received pneumococcal vaccine. The most common reasons for nonimmunization with influenza included lack of awareness (49%) and concern for side effects (18%). Responses indicated that 75 (44%) patients were at risk for HBV but only 47 (28%) had been vaccinated against the infection; of patients with previous HBV vaccination, only three of nine (33%) had measurable antibodies against hepatitis B surface antigen.

CONCLUSIONS

Immunization against selected vaccine-preventable illnesses was uncommon in patients with IBD, despite the presence of significant risk factors. Efforts to improve immunization status among patients with IBD and other chronic, immune-mediated conditions are needed.

Postexposure protection against Marburg haemorrhagic fever with recombinant vesicular stomatitis virus vectors in non-human primates: an efficacy assessment

BACKGROUND

Effective countermeasures are urgently needed to prevent and treat infections caused by highly pathogenic and biological threat agents such as Marburg virus (MARV). We aimed to test the efficacy of a replication-competent vaccine based on attenuated recombinant vesicular stomatitis virus (rVSV), as a postexposure treatment for MARV haemorrhagic fever.

METHODS

We used a rhesus macaque model of MARV haemorrhagic fever that produced 100% lethality. We administered rVSV vectors expressing the MARV Musoke strain glycoprotein to five macaques 20-30 min after a high-dose lethal injection of homologous MARV. Three animals were MARV-positive controls and received non-specific rVSV vectors. We tested for viraemia, undertook analyses for haematology and serum biochemistry, and measured humoral and cellular immune responses.

FINDINGS

All five rhesus monkeys that were treated with the rVSV MARV vectors as a postexposure treatment survived a high-dose lethal challenge of MARV for at least 80 days. None of these five animals developed clinical symptoms consistent with MARV haemorrhagic fever. All the control animals developed fulminant disease and succumbed to the MARV challenge by day 12. MARV disease in the controls was indicated by: high titres of MARV (10(3)-10(5) plaque-forming units per mL); development of leucocytosis with concurrent neutrophilia at end-stage disease; and possible damage to the liver, kidney, and pancreas.

INTERPRETATION

Postexposure protection against MARV in non-human primates provides a paradigm for the treatment of MARV haemorrhagic fever. Indeed, these data suggest that rVSV-based filoviral vaccines might not only have potential as preventive vaccines, but also could be equally useful for postexposure treatment of filoviral infections.

Acute hepatitis A and B in patients with chronic liver disease: prevention through vaccination

Retrospective and prospective studies have demonstrated that the occurrence of acute hepatitis A in patients with chronic liver disease is associated with higher rates of morbidity and mortality than in previously healthy individuals with acute hepatitis A. The mortality associated with acute hepatitis A may be particularly high in patients with preexisting chronic hepatitis C. Although acute hepatitis B in patients with preexisting chronic liver disease is less well studied, worse outcomes than in previously healthy individuals are apparent. However, numerous studies convincingly demonstrate that chronic hepatitis B virus coinfection with hepatitis C virus (or hepatitis D virus) is associated with an accelerated natural history of liver disease and worse outcomes. These observations led to studies that demonstrated the safety and efficacy of hepatitis A and hepatitis B vaccination in patients with mild-to-moderate chronic liver disease. Hepatitis A and B vaccination is less effective in patients with advanced liver disease, especially after decompensation, such as in patients awaiting liver transplantation, and in liver transplant recipients. The emerging lower rates of inherent immunity in younger individuals, higher morbidity and mortality of acute hepatitis A or B superimposed on chronic liver disease, and greater vaccine efficacy in milder forms of chronic liver disease suggest that it is a reasonable policy to recommend hepatitis A and B vaccination in patients early in the natural history of chronic liver disease.

Screening for hepatitis A and B antibodies in patients with chronic liver disease

Chronic liver disease (CLD) is highly prevalent, and hepatitis C is one of the leading causes. Acute hepatitis A or B in patients with chronic hepatitis C can lead to more severe hepatic injury and a higher fatality rate than in patients without hepatitis C. Thus, the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention and the World Health Organization recommend that persons with CLD be vaccinated against hepatitis A virus (HAV), and the ACIP and the National Institutes of Health recommend vaccination against both HAV and hepatitis B virus (HBV) in patients with chronic hepatitis C. Because coinfection with HAV or HBV in patients with chronic hepatitis C or CLD is common, antibody screening prior to hepatitis A or B vaccination can identify patients who are already immune to these viruses and thus do not need to be vaccinated. Selective hepatitis A vaccination (i.e., vaccination of patients who test negative for either HAV antibody immunoglobulin G or total antibodies to HAV) is most cost-effective in areas where the local prevalence of hepatitis A is higher than the national prevalence and in populations with higher background rates of HAV exposure compared with the general population, such as older adults, foreign-born patients, African Americans, and persons with CLD or hepatitis C. Although not usually recommended for healthy adults or those with compensated CLD because of virtually 100% postvaccination seroconversion, serologic testing after hepatitis A vaccination is recommended in patients with decompensated or advanced end-stage liver disease because of the much lower seroconversion rates in these patients. Selective vaccination against HBV in patients with CLD or hepatitis C is also recommended. Testing for hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) is considered the most efficient and reasonably cost-effective method to screen for hepatitis B serologic markers because HBsAg identifies individuals with both acute and chronic HBV infection, and anti-HBs identify those who are immune secondary to vaccination or past infection. Testing for antibodies to hepatitis B core antigen is needed to further distinguish between immunity due to vaccination and immunity due to past infection, but it is not recommended as the only screening test for HBV immunity. Postvaccination testing for hepatitis B seroconversion is recommended in all patients with CLD, especially in those with more advanced disease, because the rate of seroconversion is generally lower than in healthy adults. If patients with CLD are not adequately protected after a standard course of hepatitis B vaccination, a repeat course of vaccination using the standard schedule or an accelerated schedule (days 0, 7, and 21) should be considered.

Compliance to hepatitis B vaccination and subsequent development of seroprotection among health care workers of a tertiary care center of Saudi Arabia

BACKGROUND

There is lack of reliable data on compliance to hepatitis B virus (HBV) vaccine and development of seroprotective levels of antibodies among health care workers (HCWs) from the countries with high HBV endemicity such as Saudi Arabia. This study aimed to assess the compliance with HBV vaccine and subsequent levels of seroprotection among HCWs of a large tertiary care center of the Eastern Province of Saudi Arabia.

METHODS

All the HCWs (n = 1302) involved in direct patient care, including 374 (28.7%) physicians, 619 (47.6%) nurses, and 309 (23.7%) technicians, were enrolled for the study. Those having antibody to hepatitis B surface antigens (anti-HBs) levels less than 10 mIU/mL were advised to take 3 doses of yeast-derived recombinant HBV vaccine at 0, 1, and 6 months of 1 mL (20 microg/mL) in the deltoid muscle. Blood samples were checked for anti-HBs antibody levels by enzyme immunoassay during the initial screening of HCWs and 3 months after the third dose of HBV vaccine. The group of physicians included 34.5% (129/374) of consultants, 16.8% (63/374) of specialists, and 48.6% (182/374) of residents.

RESULTS

An overall HBV vaccine compliance rate of 71.6% (932/1302) was observed among HCWs including that of 79.5% (492/619) among nurses, 78.3% (242/309) among technicians, and 52.9% (198/374) among physicians. Thus, physicians recorded the lowest compliance (OR, 3.211; 95% CI, 2.259-4.567; P < .0001) to HBV vaccine. Among physicians, the lowest compliance of 42.3% (77/182) was observed in residents (OR, 3.690; 95% CI, 1.067-3.703; P < .0001). The overall seroprotection after vaccination was achieved in 92.2% of the compliant HCWs, and 7.8% of them failed to mount adequate response to HBV vaccine. Nonresponders included mainly the physicians (OR, 2.229; P = .05)-consultants in particular (OR, 3.476; P < .0001). The mean age of nonresponders was higher than those who mounted an adequate anti-HBs response (46.7 +/- 6.3 vs. 32.2 +/- 3.3 years OR, 1.845; 95% CI, 0.999-3.414; P < .05).

CONCLUSIONS

Poor compliance to HBV vaccine among physicians--residents in particular-is an issue of immense concern, which demands close examination and identification of the specific action that needs to be taken to enhance the uptake of the vaccine by this target population.