Effect of revaccination using different schemes among adults with low or undetectable anti-HBs titers after hepatitis B virus vaccination

Immune response to hepatitis B vaccine: An evaluation

Background:

Hepatitis B virus infection is a major public health problem in India, and all health-care workers (HCWs) need to be immunized to prevent occupational exposure. This study was done to find the hepatitis B vaccination rates, immune response, and predictors of titer <10 mIU/ml among students and HCWs of a tertiary care institution in the state of Kerala.

Materials and Methods:

This was a cross-sectional study conducted in the Department of Microbiology, Government TD Medical College, Alappuzha, Kerala, India, for a period of 1½ years between January 1, 2016, and June 30, 2017. Vaccination rates were collected through a screening proforma. Of the 1321 participants who filled the screening proforma, 5 ml of blood was collected aseptically from 579 participants who were fully vaccinated (all the three doses of vaccine) and stored at −20°C until antibody to hepatitis B surface antigen (anti-HBs) assay was done using Microlisa (Biorad). Data were analyzed using SPSS for Windows, version 16.0. (SPSS Inc., Chicago, IL, USA) (trial version).

Statistical Analysis:

Descriptive data were expressed using frequencies and percentages, and Chi-square test was applied to find the association between antibody titer <10 mIU/ml and independent variables.

Results:

Of the 1321 participants who filled up the screening proforma, the vaccination rate was 72.6%. Majority of the participants, i.e. 83.5% of doctors, 81.1% of nurses, 69.7% of students, and 21.4% of technicians, had taken all the three doses of hepatitis B vaccine. Of the fully vaccinated (n = 959) participants, 76.9% had the vaccination during adulthood and only 26.1% had it during childhood. The correlate of protection was defined as the presence of anti-HBs ≥10 mIU/ml. The mean antibody titer was 448 ± 284.97 mIU/ml ranging from 9.8 to 2000. Of the 579 participants whose titer was checked, 71 (12.3%) had a nonprotective titer of <10 mIU/ml. We found that age >35 (odds ratio [OR]: 3.85, 95% confidence interval [CI]: 2.12–6.99]), last dose >10 years (OR: 5.01, 95% CI: 2.94–8.55), no boosters or revaccination (OR: 2.94, 95% CI: 1.42–6.07), and body mass index (BMI) >25 (OR: 2.51, 95% CI: 1.44–3.39) were associated with nonprotective titer.

Conclusion:

More than a quarter of the study population who were at high risk of exposure were unvaccinated or partially vaccinated. Even after taking the full course of hepatitis B vaccine, 12.3% had titer <10 mIU/ml. Nonprotective titer was found to be associated with age >35 years, last dose taken >10 years ago, no boosters/revaccination, and BMI ≥25.

Long-term immune protection against HBV: associated factors and determinants

In Italy, vaccination against hepatitis B became compulsory for all the newborns and 12-years-old adolescents in 1991. The main purpose of this study was to evaluate the persistence of long-term protection against HBV in medical students of the University of L’Aquila and in postgraduates Medical Doctors (HCWs) working in San Salvatore Hospital. The second aim was to study the variables associated with a protective anti-HBs antibody level, such as age at vaccination, gender, time elapsed from the last dose of vaccination.

Three hundred and forty-two subjects were enrolled from January 2017 to January 2019 and a blood sample was collected to evaluate the levels of serum HBsAg, anti-HBs and anti-HBc. Statistical analysis calculated a multivariable logistic regression model to examine predictors of a protective anti-HBs titer. The larger part (239, 70%) of the students had an anti-HBs titer >10 mIU/mL, those were statistically significant older (26.7 vs 24.5 years, p < .001), vaccinated at age 12 years (83.5% vs 59.9% among vaccinate at infancy, p < .001) and more frequently attending postgraduate medical school (80.8% vs 57.5% among healthcare profession school, p < .001). The multivariable logistic regression model showed that HBV vaccination at age of 12 was significantly and independently associated with protective titers (OR = 10.27, p = .019).

The results agreed with literature on HBV vaccination, confirming the efficacy of vaccination after 20 years. In particular, our results suggest that adolescent administration is the main predictor of a protective title, regardless of gender, course and years since vaccinations.

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.

Healthy adult vaccination: An urgent need to prevent hepatitis B in China

Prevalence of hepatitis B is still high among adults in China, athough the prevalence in children has decreased dramatically. Immunization against hepatitis B among adults is urgently required. Through analyzing the immunogenicity of different doses, schedules and booster immunization among adults, we recommend 10 or 20 μg with a 0-1-6-month schedule or a 0-1-12-month schedule for migrant adults. For immunity failure, increasing the dose or covalent vaccine is suggested to provide protective antibodies. To enhance immunity among adults, hepatitis B vaccine should be included in health insurance.

Comparison of the effect of increased hepatitis B vaccine dosage on immunogenicity in healthy children and adults

Hepatitis B (HepB) infection remains a global public health problem, particularly in China. Vaccination for children and adult who are unvaccinated is an effective method for preventing the disease. In this study, we aimed to compare the effects of increased dosage of HepB vaccine on immunogenicity in healthy children and adults. A phase III, controlled, double-blinded clinical trial was performed. The subjects were assigned into groups I (age 5-14 y), II (age 15-24 y), and III (age ≥ 25 y). Subjects were randomly administered either 10 or 5 μg recombinant HepB vaccine; blood samples were collected before and after vaccination to estimate immunogenicity. The results showed that the seroconversion rate and geometric mean concentration of antibody to hepB surface antigen (anti-HBs) did not differ significantly between the dosages in each age group. Anti-HBs levels were reduced with age, and this effect was more obvious in adults administered 5 μg HepB vaccine. In conclusion, both vaccine dosages could be used to immunize children, and the 10 μg vaccine could be used for adults ages 15-24 y, whereas a higher dosage of the HepB vaccine may be required for adults ages 25 y and older.

Plasminogen kringle 5 induces endothelial cell apoptosis by triggering a voltage-dependent anion channel 1 (VDAC1) positive feedback loop

Human plasminogen kringle 5 (K5) is known to display its potent anti-angiogenesis effect through inducing endothelial cell (EC) apoptosis, and the voltage-dependent anion channel 1 (VDAC1) has been identified as a receptor of K5. However, the exact role and underlying mechanisms of VDAC1 in K5-induced EC apoptosis remain elusive. In the current study, we showed that K5 increased the protein level of VDAC1, which initiated the mitochondrial apoptosis pathway of ECs. Our findings also showed that K5 inhibited the ubiquitin-dependent degradation of VDAC1 by promoting the phosphorylation of VDAC1, possibly at Ser-12 and Thr-107. The phosphorylated VDAC1 was attenuated by the AKT agonist, glycogen synthase kinase (GSK) 3β inhibitor, and siRNA, suggesting that K5 increased VDAC1 phosphorylation via the AKT-GSK3β pathway. Furthermore, K5 promoted cell surface translocation of VDAC1, and binding between K5 and VDAC1 was observed on the plasma membrane. HKI protein blocked the impact of K5 on the AKT-GSK3β pathway by competitively inhibiting the interaction of K5 and cell surface VDAC1. Moreover, K5-induced EC apoptosis was suppressed by VDAC1 antibody. These data show for the first time that K5-induced EC apoptosis is mediated by the positive feedback loop of "VDAC1-AKT-GSK3β-VDAC1," which may provide new perspectives on the mechanisms of K5-induced apoptosis.

Pigment epithelial-derived factor (PEDF)-triggered lung cancer cell apoptosis relies on p53 protein-driven Fas ligand (Fas-L) up-regulation and Fas protein cell surface translocation

Pigment epithelium-derived factor (PEDF), a potent antiangiogenesis agent, has recently attracted attention for targeting tumor cells in several types of tumors. However, less is known about the apoptosis-inducing effect of PEDF on human lung cancer cells and the underlying molecular events. Here we report that PEDF has a growth-suppressive and proapoptotic effect on lung cancer xenografts. Accordingly, in vitro, PEDF apparently induced apoptosis in A549 and Calu-3 cells, predominantly via the Fas-L/Fas death signaling pathway. Interestingly, A549 and Calu-3 cells are insensitive to the Fas-L/Fas apoptosis pathway because of the low level of cell surface Fas. Our results revealed that, in addition to the enhancement of Fas-L expression, PEDF increased the sensitivity of A549 and Calu-3 cells to Fas-L-mediated apoptosis by triggering the translocation of Fas protein to the plasma membrane in a p53- and FAP-1-dependent manner. Similarly, the up-regulation of Fas-L by PEDF was also mediated by p53. Furthermore, peroxisome proliferator-activated receptor γ was determined to be the upstream regulator of p53. Together, these findings uncover a novel mechanism of tumor cell apoptosis induced by PEDF and provide a potential therapeutic strategy for tumors that are insensitive to Fas-L/Fas-dependent apoptosis because of a low level of cell surface Fas.

Hepatitis B virus: Where do we stand and what is the next step for eradication?

Hepatitis B (HB) virus (HBV) infection, which causes liver cirrhosis and hepatocellular carcinoma, is endemic worldwide. Hepatitis B vaccines became commercially available in the 1980s. The World Health Organization recommended the integration of the HB vaccine into the national immunisation programs in all countries. HBV prevention strategies are classified into three groups: (1) universal vaccination alone; (2) universal vaccination with screening of pregnant women plus HB immune globulin (HBIG) at birth; and (3) selective vaccination with screening of pregnant women plus HBIG at birth. Most low-income countries have adopted universal vaccine programs without screening of pregnant women. However, HB vaccines are not widely used in low-income countries. The Global Alliance for Vaccine and Immunization was launched in 2000, and by 2012, the global coverage of a three-dose HB vaccine had increased to 79%. The next challenges are to further increase the coverage rate, close the gap between recommendations and routine practices, approach high-risk individuals, screen and treat chronically infected individuals, and prevent breakthrough infections. To eradicate HBV infections, strenuous efforts are required to overcome socioeconomic barriers to the HB vaccine; this task is expected to take several decades to complete.