Humoral and cellular immune responses to hepatitis B vaccination in hepatitis B surface antigen-carrier children who cleared serum-hepatitis B surface antigen

Role of hepatitis B surface antibody in seroreversion of hepatitis B surface antigen in patients achieving hepatitis B surface antigen loss with pegylated interferon-based therapy

It is unclear whether hepatitis B surface antibody (HBsAb) confers clinical benefits after HBsAg seroclearance, especially in hepatitis B surface antigen (HBsAg) seroreversion and maintenance of HBsAb. We evaluated this in patients (n = 222) with HBsAg loss following treatment with pegylated interferon (PEG-IFN)-based therapy who completed a 48-week follow-up period. Serum hepatitis B virus (HBV) markers and biochemical indicators were evaluated every 3 months. The primary endpoint was HBsAg seroreversion. Factors associated with HBsAg seroreversion were also investigated. HBsAb ≥100 mIU/ml resulted in a lower HBsAg seroreversion rate than an HBsAb-negative status (5.5% vs. 29.5%, p < .001); however, the seroreversion rate was not significantly different between patients with HBsAb 10-100 mIU/ml and those in the HBsAb-negative group. Patients with HBsAb ≥100 mIU/ml had a lower HBsAb loss rate than those with HBsAb 10-100 mIU/ml (7.3% vs. 21.7%, p = .005). The final HBsAg seroreversion and HBV DNA relapse rates were 13.5% and 1.8%, respectively. HBsAb ≥100 mIU/ml at the off-treatment time (odds ratio [OR] 0.110, 95% confidence interval [CI]: 0.034-0.353, p < .001) and treatment time to attain HBsAg loss >28 weeks (OR 2.508, 95% CI: 1.068-5.890, p = .035) were predictors of HBsAg seroreversion. Consolidation therapy for 12-24 weeks resulted in higher HBsAb titres than consolidation therapy for ≤12 weeks in HBsAb-negative patients at the off-treatment time (p < .001). HBsAg seroconversion with HBsAb ≥100 mIU/ml decreases HBsAg seroreversion and provides an efficient maintenance rate of HBsAb. HBsAg seroconversion with high HBsAb titres may be clinically beneficial for chronic hepatitis B treated with PEG-IFN-based therapy.

Is hepatitis B antigen in cord blood an immunotolerogen playing a critical role in the pathogenesis of chronic hepatitis B?

Recently, we showed that infants with or without fetal hepatitis B e antigen (HBeAg) exposure had comparable antibody response to hepatitis B vaccination and proposed that fetal HBeAg exposure appears to not induce immunotolerance to HBV. Here, we summarized the different results on the topic of fetal HBeAg exposure in inducing immunotolerance to HBV nucleocapsid protein, and the evidence to back up that the tendency of high infection rate in infants of HBeAg-positive mothers is more likely associated with higher maternal viral loads and is less likely associated with the fetal HBeAg exposure. We consider that whether fetal HBeAg exposure plays an important role in the pathogenesis of chronic HBV infection remains to be an open question.

Association of genetic variation in B-cell activating factor with chronic hepatitis B virus infection

The outcome of hepatitis B virus (HBV) infection is considered to be related to the host immunogenetic susceptibility. B cell activating factor (BAFF) is involved in both B cell and T cell mediated immunity and its circulating levels were shown to be significantly elevated in HBV-related liver diseases. This study examined BAFF rs9514828 and rs12583006 polymorphisms in 386 patients with various liver diseases related to chronic HBV infection, 69 HBV infection resolvers, and 191 healthy controls. Both rs9514828 and rs12583006 polymorphisms and serum BAFF levels were determined in 232 patients with chronic HBV infection, and 61 healthy controls. The results showed that patients with chronic hepatitis had higher frequencies of rs9514828 genotype TT (19.75% vs. 11.86%, OR=2.397, 95% CI=1.121-5.125, P=0.023), genotypes CT+TT (74.69% vs. 63.55%, OR=1.478, 95% CI=1.050-2.080, P=0.045), and allele T (47.22% vs. 37.72%, OR=1.478, 95% CI=1.050-2.080, P=0.025) compared with patients with cirrhosis. Patients with chronic HBV infection and HBV infection resolvers had higher frequency of rs9514828 and rs12583006 haplotype TA compared with healthy controls (21.6% vs. 15.0%, OR=1.672, 95% CI=1.138-2.456, P=0.009 and 27.3% vs. 15.0%, OR=2.258, 95%CI=1.272-4.007, P=0.005, respectively). The rs9514828 and rs12583006 genotypes had no significant association with serum BAFF levels. These results suggest that the rs9514828 allele T may predispose to the liver inflammation in chronic HBV infection, and the rs9514828 and rs12583006 polymorphisms may combinatorially confer susceptibility to chronic HBV infection and resolution of the infection, possibly not through direct effect on serum BAFF levels.

Hepatitis B surface antigen could contribute to the immunopathogenesis of hepatitis B virus infection

Various findings concerning the clinical significance of quantitative changes in hepatitis B surface antigen (HBsAg) during the acute and chronic phase of hepatitis B virus (HBV) infection have been reported. In addition to being a biomarker of HBV-replication activity, it has been reported that HBsAg could contribute to the immunopathogenesis of HBV persistent infection. Moreover, HBsAg could become an attractive target for immune therapy, since the cellular and humeral immune response against HBsAg might be able to control the HBV replication and life cycle. However, several reports have described the immune suppressive function of HBsAg. HBsAg might suppress monocytes, dendritic cells (DCs), natural killer (NK), and natural killer T (NK-T) cells by direct interaction. On the other hand, cytotoxic T lymphocytes (CTLs) and helper T (Th) cells were exhausted by high amounts of HBsAg. In this paper, we focused on the immunological aspects of HBsAg, since better understanding of the interaction between HBsAg and immune cells could contribute to the development of an immune therapy as well as a biomarker of the state of HBV persistent infection.

Surface antibody and cytokine response to recombinant Chinese hamster ovary cell (CHO) hepatitis B vaccine

OBJECTIVE

To compare the immune responses of the 10 μg and 20 μg doses of CHO hepatitis B vaccine on adults.

METHODS

Adults aged 18-45 years who gave a history of never having received hepatitis B vaccine and lacked serologic evidence of infection to hepatitis B virus (HBV) infection or previous vaccination were enrolled into the study. A total of 642 eligible participants were randomized to receive 3 doses of either the 10 μg or the 20 μg formulation of CHO hepatitis B vaccine in a 0-1-6 month schedule. Each study subject had a serologic specimen collected one month following the third vaccine dose that was tested for markers of HBV infection and anti-HBs by Abbott I2000. Persons who tested negative for anti-HBs negative persons were tested for HBV DNA. Logistic regression was used to identify factors associated with antibody response. Among the participants, 153 subjects had their lymphocytes cultivated and tested for cytokine production. Enzyme-linked immunospot (ELISPOT) was used to test spot numbers of IL-4, IFN-γ which produced by lymphocyte.

RESULTS

The anti-HBs seroconversion rate was 88.8% (95% CI: 85.4-92.2%) and 95.3% (95% CI: 93.0-97.6%), respectively in 10 μg and 20 μg group. Geometric mean titers (GMT) were 173.42 mIU/ml and 585.51 mIU/ml, respectively in 10 μg and 20 μg groups. Multivariate analysis demonstrated that diabetes, spouse is hepatitis B virus infector, older age and receipt of the 10 μg dose were all negatively associated with antibody response (P<.05). Cellular immunity results showed: IL-4 immunity spot numbers in 20 μg group was higher than 10 μg group. With anti-HBs increased, the IL-4 immunity spot numbers increased significantly which had significant positive correlation (Spearman coefficient=0.538, P<0.0001). IFN-γ spot numbers had no statistical significant between the two groups.

CONCLUSION

The humoral immunity and cytokines response among the group that received the 20 μg CHO hepatitis B vaccine dose was superior compared to the group that received the 10 μg dose. The 20 μg dose of CHO hepatitis B vaccine should be prioritized for adult vaccination programs in China.

Toll-like receptors and cytokines/cytokine receptors polymorphisms associate with non-response to hepatitis B vaccine

It is well documented that 5-10% hepatitis B adult vaccinees are non- and hypo-responders and probably are not adequately protected against hepatitis B virus (HBV) infection. The sequence variations of genes involved in processes such as pathogen recognition, antigen processing and presentation, and differentiation/maturation of lymphocytes may affect the duration and intensity of protective humoral immune response to the hepatitis B vaccine. In this study, frequencies of 53 known SNPs within 21 candidate genes were analyzed among 46 responders and 24 non-responders. Four SNPs (rs2243248, rs1805015, rs1295686 and rs3804100) in IL-4, IL-4RA, IL-13 and TLR2 genes were found significantly associated with the vaccinees' status of serum anti-HBV response triggered by the vaccine (P<0.05). Two SNPs (rs1295686 and rs1805015) also showed significant association with the vaccine-induced immune response when analyzed together with risk factors such as age and gender, by multivariable logistic regression analysis (P<0.05). Further, haplotype analysis showed that the AG haplotype defined by SNPs rs1143633 (IL-1B; intron) and rs1143627 (IL-1B; intron) was present more frequently in non-responders than in responders (P=0.035). Thus, specific SNPs in genes of cytokines/cytokine receptors and TLR2 were associated with status of the hepatitis B vaccine-induced protective humoral immune response.

Impact of hepatitis B vaccination on hepatitis B disease and nucleic acid testing in high-prevalence populations

Hepatitis B virus (HBV) infection is highly prevalent in Asia, Africa, southern Europe and Latin America, HBV vaccination has effectively reduced the acute and chronic infection rates as well as related complications in the vaccinated children. The incidence of hepatocellular carcinoma in children has been reduced to approximately 25% of the incidence before the vaccination program, and fulminant hepatitis in children has also been reduced after universal hepatitis B vaccination. HBV DNA sero-positive rate was 98-100% in HBsAg positive vaccinated children, while the positive rate was only 11-20% in those vaccinees with a negative HBsAg but positive anti-HBc reaction. Hepatitis B surface gene mutants in HBV DNA positive children increased gradually from 7.8% before the vaccination program, to 19.6%, 28.1% and 23.1% at 5, 10 and 15 years after the vaccination program. Long-term follow-up of vaccinated children has confirmed that universal HBV vaccination in infancy has produced adequate protection up to 14 years of age. The annual decay rate of hepatitis B surface antibody (anti-HBs) was 10.2% in children who did not receive a booster dose. The new HBV infection rate was not different between those who did and those who did not receive a booster dose of HBV vaccine. During a follow-up period of seven years for 1200 vaccinated 7-year-old children in Taiwan, the mean annual hepatitis B core antibody sero-conversion rate was 0.2%. All were negative for HBV DNA. No new chronic HBV infections developed. A booster dose of HBV vaccine is not recommended in children under 15 years of age. Systematic HBV DNA screening of a large population such as blood donors may be instrumental in following the long-term effect of the universal vaccination program on the incidence of silent HBV infection and vaccine escape mutants.

Hepatitis B immunisation induces higher antibody and memory Th2 responses in new-borns than in adults

New-borns raise limited antibody responses to most T cell-dependent antigens but little is known about neonatal T lymphocyte responses to vaccines. In this study, we compared the immune response induced by the hepatitis B vaccine in new-borns and nai;ve adults. Infants produced markedly higher serum anti-hepatitis B surface (HBs) antibody titres than adults. This was not associated with greater HBs Ag-specific Th2 cytokine responses but with lower primary IFN-gamma responses. At 1 year, the infant memory response to HBs Ag was characterised by higher Th2 responses than those of adults. We conclude that neonatal antibody and T cell responses to hepatitis B vaccine differ from those induced in adults.

Identification of a novel pre-S2 mutation in a subgroup of chronic carriers with spontaneous clearance of hepatitis B virus surface antigen

BACKGROUND AND AIM

The aim of the present study was to investigate whether spontaneous seroclearance of hepatitis B surface antigen (HBsAg) in patients with chronic hepatitis B could be attributed to the presence of pre-S/S gene mutations.

METHODS

Of 34 hepatitis B virus (HBV) carriers who experienced spontaneous seroclearance of HBsAg, 30 were still seropositive for HBV DNA. The serum samples of these carriers were subjected to sequence analysis.

RESULTS

A novel pre-S2 mutation, G149R, was found in nine (group I) but not in 17 (group II) patients carrying HBV DNA with intact pre-S/S reading frames. In the remaining four patients (group III), only aberrant pre-S/S transcripts were found in their sera. Distinct patterns of amino acid substitutions specific to group I and II patients were identified. Superinfection by hepatitis C or D virus occurred predominantly in group II patients (P = 0.019). Superinfection by HBV of a different genotype occurred predominantly in patients without hepatitis C or D virus superinfection (P = 0.013). Site-directed mutagenesis experiments showed that secretion of HBsAg was not defective in the pre-S2 G149R mutant.

CONCLUSIONS

In a particular subgroup (group I) of patients, seroclearance of HBsAg was not caused by superinfection of other hepatitis viruses, nor was it caused by failure of HBsAg secretion or detection. Instead, a yet unrecognized mechanism associated with emergence of a novel pre-S2 mutation is responsible.

Hepatitis B and hepatitis C co-infection in patients with HIV

HAART has increased the life expectancy of patients with HIV. However, as their life expectancy increases, it becomes increasingly important to focus on the management of concurrent illnesses such as chronic HBV and HCV infections which have the potential to increase mid to long term morbidity and mortality. Shared epidemiological risks have resulted in the HIV infected population having a higher incidence of both HBV and HCV than those uninfected with HIV. Co-infection with HIV modifies the natural history of HBV infection, increasing the rate of viral replication, risk of carriage and chronic hepatitis but without increasing liver necroinflammatory processes. In chronic HCV infection, the presence of HIV enhances the risk of severe liver disease. There is no evidence as yet that HBV directly impacts on HIV disease progression but HCV infection increases the risk of death or an AIDS defining illness and impairs CD4+ T cell recovery during antiretroviral therapy. Treatment of either hepatitis virus is complex because of pharmacokinetic interactions with components of HAART regimens.

Natural history of hepatitis B virus infection in children

Hepatitis B virus (HBV) infection during childhood can cause acute, fulminant or chronic hepatitis, liver cirrhosis, and liver cancer. Approximately 90% of the infants of hepatitis B e antigen (HBeAg) seropositive mothers become hepatitis B surface antigen (HBsAg) carriers. Children chronically infected are mostly asymptomatic. Although liver damage is usually mild during childhood, severe liver disease, including cirrhosis and hepatocellular carcinoma, may develop insidiously for 2-7 years. Spontaneous HBeAg seroconversion occurs gradually as the age of the child increases. Viral replication is reduced during this process, which is usually preceded by an elevation of aminotransferases. In a long-term follow-up study, the annual HBeAg seroconversion rate was 4-5% in children older than 3 years of age and less than 2% in children under 3 years. The annual seroconversion rate of HBsAg was very low (0.56%). Age at infection, maternal HBsAg and HBeAg status, host immune status, and possibly the HBV strain are the main factors determining the course of HBV infection in children.

Chronic hepatitis virus infection in children

Hepatitis B and C viruses (HBV and HCV) are the two main hepatitis viruses causing chronic liver diseases in children. In hyperendemic areas, nearly half of the primary infection in chronic HBV carriers occurs during the perinatal period through the transmission from hepatitis B e antigen (HBeAg)-positive mothers. The other half are from horizontal transmission mainly through intrafamilial spread or injection using unsterilized needles. During the natural course of chronic HBV infection, spontaneous HBeAg/anti-HBe seroconversion occurs very rarely (2% annually) before 3 years of age. After 3 years of age, the HBeAg seroconversion rate increases gradually to 5% per year. Those with mothers who are hepatitis B carriers tend to clear HBeAg slower than those whose mothers are non-carriers. Transplacental HBeAg may cause T cell tolerance in infected children. Universal HBV immunization programmes have been effective in reducing the hepatitis B carrier rate more than 10-fold, and the incidence of hepatocellular carcinoma in children has also been decreased significantly. Hepatitis C virus infection occurs mainly in high-risk children, such as those who received blood products (blood diseases, malignancies, post-open heart surgery etc.), children of HCV-infected mothers, and in hyperendemic areas, from injection using unsterile needles. Mother-to-infant transmission occurs on average in 5% of infants of viraemic mothers. The maternal HCV-RNA titre is the most important factor determining the infectivity. Chronicity developed in 60-80% of HCV-infected children. Although transient or persistent elevation of aminotransferases occurs frequently in chronically HCV-infected children, liver histology showed minimal or mild changes only. The most prevalent genotype of HCV in children is Ib. Screening of the blood products for HCV antibody has markedly reduced the rate of HCV infection in children at risk. However, vaccine development is needed to prevent mother-to-infant transmission and other routes of infections.