Association between the frequency of class II HLA antigens and the susceptibility to intrauterine infection of hepatitis B virus

High resolution HLA-DRB1 analysis and shared molecular amino acid signature of DRβ1 molecules in Occult hepatitis B infection

AIM

To investigate the association of human leukocyte antigen (HLA)-DRB1 alleles and the variations of polymorphic amino acid changes in DRβ1 chain in Shaanxi Han population with Occult hepatitis B infection (OBI).

METHODS

High-resolution HLA-DRB1 genotyping was performed in 107 OBI carriers and 280 normal controls. Sequence information was used to assign which amino acids were encoded at all polymorphic positions. Three-dimensional modeling was performed to explore the effect of the key residues on the HLA-DRB1 molecule.

RESULTS

Strong susceptible association for allele DRB1*07:01 was observed in OBI carriers. The amino acid variation at HLA-DRβ1 molecule revealed susceptible associations for residues Gln^4β, Val^57β(P9), Ser^60β(P9) and Val^78β(P4), the amino acids Arg^4β, Asp^57β(P9), Tyr^60β(P9) and Tyr^78β(P4) showed protective associations.

CONCLUSION

Alleles DRB1*07:01 showed strong susceptible associations in OBI carriers. The amino acid variations in DRβ molecules revealed significant molecular markers for susceptibility and protection from OBI in Shaanxi Han population.

Host Genetic Determinants of Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection is still a major health problem worldwide. Recently, a great number of genetic studies based on single nucleotide polymorphisms (SNPs) and genome-wide association studies have been performed to search for host determinants of the development of chronic HBV infection, clinical outcomes, therapeutic efficacy, and responses to hepatitis B vaccines, with a focus on human leukocyte antigens (HLA), cytokine genes, and toll-like receptors. In addition to SNPs, gene insertions/deletions and copy number variants are associated with infection. However, conflicting results have been obtained. In the present review, we summarize the current state of research on host genetic factors and chronic HBV infection, its clinical type, therapies, and hepatitis B vaccine responses and classify published results according to their reliability. The potential roles of host genetic determinants of chronic HBV infection identified in these studies and their clinical significance are discussed. In particular, HLAs were relevant for HBV infection and pathogenesis. Finally, we highlight the need for additional studies with large sample sizes, well-matched study designs, appropriate statistical methods, and validation in multiple populations to improve the treatment of HBV infection.

Genetic variant in CXCL13 gene is associated with susceptibility to intrauterine infection of hepatitis B virus

Intrauterine infection of hepatitis B virus (HBV), which accounts for the majority of mother-to-child transmission, is one of the main reasons for the failure of combined immunoprophylaxis against the transmission. Recent studies have identified that genetic background might influence the susceptibility to intrauterine infection of HBV. We conducted this study to investigate the associations between 10 genetic variants in 9 genes (SLC10A1, HLA-DP, HLA-C, CXCR5, CXCL13, TLR3, TLR4, TLR9 and UBE2L3) of mothers and their neonates and HBV intrauterine infection. A significantly decreased risk of HBV intrauterine transmission were found among mothers who carried the rs355687 CT genotypes in CXCL13 gene compared to those with CC genotypes (OR = 0.25, 95% CI, 0.08–0.82, P = 0.022); and a marginally significantly decreased risk was also observed under the dominant model (OR = 0.34, 95% CI, 0.11–1.01, P = 0.052). Besides, neonatal rs3130542 in HLA-C gene was found to be marginally significantly associated with decreased risk of HBV intrauterine infection under the additive model (OR = 0.55, 95% CI, 0.29–1.04, P = 0.064). However, we found no evidence of associations between the remaining 8 SNPs and risk of HBV intrauterine infection among mothers and their neonates. In conclusion, this study suggested that genetic variant in CXCL13 gene was associated with susceptibility to intrauterine infection of HBV.

Clinical Relevance of HLA Gene Variants in HBV Infection

Host gene variants may influence the natural history of hepatitis B virus (HBV) infection. The human leukocyte antigen (HLA) system, the major histocompatibility complex (MHC) in humans, is one of the most important host factors that are correlated with the clinical course of HBV infection. Genome-wide association studies (GWASs) have shown that single nucleotide polymorphisms (SNPs) near certain HLA gene loci are strongly associated with not only persistent HBV infection but also spontaneous HBV clearance and seroconversion, disease progression, and the development of liver cirrhosis and HBV-related hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB). These variations also influence the efficacy of interferon (IFN) and nucleot(s)ide analogue (NA) treatment and response to HBV vaccines. Meanwhile, discrepant conclusions were reached with different patient cohorts. It is therefore essential to identify the associations of specific HLA allele variants with disease progression and viral clearance in chronic HBV infection among different ethnic populations. A better understanding of HLA polymorphism relevance in HBV infection outcome would enable us to elucidate the roles of HLA SNPs in the pathogenesis and clearance of HBV in different areas and ethnic groups, to improve strategies for the prevention and treatment of chronic HBV infection.

Single-nucleotide substitution of Hepatitis B virus in intrauterine infection

The relationship between hepatitis B virus (HBV) gene polymorphism and intrauterine infection has not been completely illuminated. Six pairs of mother and infant from intrauterine infection group and six mothers from nonintrauterine infection group in the previous study were randomly selected and separately divided into group M (Mother group), group N (Neonate group) and group NM (Negative-mother group) in this study. We found that age, gestational weeks, HBsAg titre, HBeAg titre and HBV DNA level of mothers from group M and group NM were not significantly different. Pre-S1/S2 and S regions in HBV genome were amplified, inserted into pUC19 plasmid and sequenced. It was found that all clone sequences clustered into genotype C (AY123041) through the Genotyping tool in NCBI and phylogenetic trees. Compared with AY123041, there were 20 (11 plus 9) mutations significantly different in the three groups. Most of the mutations were synonymous in pre-S1/S2/S region, while mutations of C2990T, T3205A, A167G, C407A, A667T and A680C resulted in amino acid substitution of A90V, S162T, T47A, P127T, L213F and I218L, respectively. In addition, most of the 20 mutations caused amino acid substitution in polymerase region for the tight structure of HBV genome. The occurrence and location of mutations indicated that mutation of C2990T only existing in group NM may serve as an index for nonintrauterine infection. In contrast, the incidence of intrauterine HBV infection from mothers with mutation of T3205A was lower. Then, mutations of G403A, T670G, A673G, A167G, C407A, A667T and A680C may be closely related to intrauterine HBV infection.

Evaluation of neonatal Toll-like receptors 3 (c.1377C/T) and 9 (G2848A) gene polymorphisms in HBV intrauterine transmission susceptibility

To investigate whether single nucleotide polymorphisms (SNPs) in Toll-like receptors (TLRs) 3 and 9 affect the susceptibility of hepatitis B virus (HBV) intrauterine transmission, we genotyped 399 neonates for TLR3 (c.1377C/T) [rs3775290] and TLR9 (G2848A) [rs352140] using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). A femoral venous blood sample was obtained from these subjects. Hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) were measured using chemiluminescence immunoassay kits and hepatitis B virus DNA (HBV DNA) levels were determined by fluorescence quantitative PCR assay. Our results showed that when adjusting for maternal HBeAg, maternal HBV DNA and mode of delivery, allele 'T' for SNP c.1377C/T was significantly associated with HBV intrauterine transmission susceptibility [adjusted OR (aOR) 0.55, 95% confidence interval (CI) 0.34-0.91, P = 0.020] and the TT genotype decreased the risk of HBV intrauterine transmission (aOR 0.28, 95% CI 0.09-0.91, P = 0.033). Allele 'A' for SNP G2848A was significantly associated with HBV intrauterine transmission susceptibility (aOR 0.62, 95% CI 0.39-1.00, P = 0.048) and the GA genotype protected neonates from HBV intrauterine transmission (aOR 0.45, 95% CI 0.22-0.93, P = 0.031). The TLR3 (c.1377C/T) and TLR9 (G2848A) polymorphisms may be relevant for HBV intrauterine transmission susceptibility, although the reduction in risk to HBV intrauterine transmission is modest and the biological mechanism of the observed association merits further investigation.

Association between single-nucleotide polymorphisms and early spontaneous hepatitis B virus e antigen seroconversion in children

BACKGROUND

The disease progression following hepatitis B virus (HBV) infection is associated with single-nucleotide polymorphisms (SNPs). However, the role of SNPs in chronic HBV infection in children remains unclear. Here, we investigate the association between SNPs and early spontaneous hepatitis B e antigen (HBeAg) seroconversion in children with chronic hepatitis B infection.

METHODS

This was a retrospective cohort study. We genotyped seven SNPs in the following genes, interleukin (IL)-10 (rs1800871 and rs1800872), human leukocyte antigen (HLA)-DPA1 (rs3077), HLA-DPB1 (rs9277535), HLA-DQB2 (rs7453920), HLA-DQB1 (rs2856718), and IL28B (rs8099917), in patients with chronic HBV infection using PCR and sequencing. These variants were analyzed for an association with early HBeAg seroconversion in children.

RESULTS

Of 225 Japanese patients with chronic hepatitis B virus infection (male/female: 105/120, median age at initial visit: 6 years; range 0-44 years), 52 achieved spontaneous HBeAg seroconversion at the age of 10 years or younger (G1: early seroconversion group), and 57 did not achieve spontaneous HBeAg seroconversion under the age of 20 years (G2: late or no seroconversion group). Of the seven SNPs, only the HLA-DPA1 SNP displayed a low p-value (P = 0.070), but not significant, to have early HBeAg seroconversion in the dominant model and in the allele model (P = 0.073) using the chi-square test. The association study found a low p-value, but not significant, to have early HBeAg seroconversion in the dominant model for HLA-DPA1 (genotype TC + TT vs. CC, P = 0.070, odds ratio: 2.016, 95% confidence interval: 0.940-4.323) using a logistic regression model.

CONCLUSION

Although the HLA-DPA1 SNP did not show a statistically significant association with early HBeAg seroconversion in this study, the HLA-DPA1 SNP might increase the likelihood of achieving early spontaneous HBeAg seroconversion in children.

Prevention of neonatal hepatitis B virus transmission

Hepatitis B virus (HBV) vertical transmission remains a worldwide issue but is fairly uncommon in the western world due to routine screening and vaccination. Universal screening of pregnant women during the second trimester facilitates interruption of mother-to-child transmission (MTCT) by identifying HBV-infected mothers for whom intervention may reduce MTCT risk. HBV DNA level is the single most important predictor of MTCT. Other risk factors include HBeAg, HBe Ab, anti-HB core IgG, and HIV status. Current recommendations for infants born to HBsAg-positive mothers include administration of HBIG within 12 hours of birth and first dose of HBV vaccine within 24 hours of birth. Antiviral therapy is recommended in the third trimester of pregnancy in a subset of patients based on HBeAg and HBV DNA status for prophylaxis of MTCT, although discontinuation of antivirals after delivery is associated with significant increased risk of flares. This article outlines the data for prevention of vertical transmission of HBV.

Association of HLA alleles with the responsiveness to hepatitis B virus vaccination in Korean infants

Hepatitis B virus (HBV) vaccination is the most effective means of countering HBV-related morbidity and mortality, and individuals who do not respond to vaccination (non-responders) are problematic. The aim of the present study was to investigate associations between HLA and responsiveness to HBV vaccine in Korean infants. A total of 944 healthy Korean infants 9-12 months old were enrolled, and HLA distribution was compared among subgroups in accordance with the response to HBV vaccination. The HLA distribution of the subjects was similar to known Korean population data and did not deviate from the HWE proportions. The alleles that showed positive associations with non-responsiveness (<10mIU/mL) or low antibody titer (<100mIU/mL) were HLA-A*33, B62, DRB1*04, and DRB1*07, while the alleles A*02 and DRB1*08 showed negative associations. Among these alleles, B62, DRB1*07 and DRB1*08(-) showed significant associations with a poor or decreased response to vaccination even after correction (OR=1.83, 1.99, 5.63; pc<0.05) and also showed dose effects. After stratification by other associated alleles at different loci, B62 and DRB1*07 were independently associated with non-responsiveness, but A*02(-) and DRB1*08(-) lost their individual associations. The combined association of A*02(-)-DRB1*08(-) and B62-DRB1*08(-) was significant (OR=25.2 and 24.5; pc<0.05). Although the hierarchy is not clear, we can assume the following: (i) B62 and DRB1*07 have independent effects, (ii) DRB1*08(-) has a very strong and synergic effect, and (iii) there is probability of a third factor controlling A*02(-) and DRB1*08(-) with an effect on non-responsiveness to HBV vaccination in Korean infants.

The role of the human leukocyte antigen system in retinopathy of prematurity: a pilot study

AIM

To assess the association between the human leukocyte antigen system and retinopathy of prematurity.

METHODS

Neonates of <32 weeks of gestational age, born at two level III neonatal intensive care units from January 2000 to December 2001 and from January 2006 to June 2009, were included in the study. Demographic and clinical data were recorded, and retinopathy was classified according to the International Classification. Epithelial cells were collected from the oral cavity and the HLA were studied using the PCR/SSO method. Univariate and multivariate analyses were performed using SPSS® v.18.

RESULTS

We evaluated 156 neonates, including 82 (52.6%) males. Median gestational age was 29 (23-31) weeks, and median birth weight was 1030 (525-1935) grams. Seventy (44.9%) of the neonates developed retinopathy. Alleles HLA-B*38, HLA-Cw*12, HLA-DRB1*09, HLA-DRB1*14 (univariate analysis) and HLA-A*68 and HLA-Cw*12 were associated to retinopathy (multivariate analysis).

CONCLUSION

The results suggest that the HLA system may be associated with the development of retinopathy of prematurity. A large-scale population-based study should be performed to clarify this association.

Association of human leukocyte antigen class I polymorphism with spontaneous clearance of hepatitis B surface antigen in Qidong Han population

AIM

To investigate whether HLA class I polymorphisms could influence the clearance of hepatitis B surface antigen (HBsAg) in Qidong Han population.

METHODS

We genotyped HLA-A, -B, and -C loci of 448 individuals with HBV persistent infection and 140 persons with spontaneous clearance of HBsAg by polymerase chain reaction with sequencing based typing (PCR/SBT). All the individuals were unrelated males enrolled from Qidong Han population and were followed up for 10 years.

RESULTS

The frequency of HLA-A∗33:03:01G was increased in persistent HBV infection group (P value is 0.028), while frequency of HLA-B∗13:01:01G was increased in HBsAg clearance group (P value is 0.0004).

CONCLUSION

These findings suggested that the host HLA class I polymorphism is an important factor in determining the outcomes of HBV infection.

Association between HLA-DRB1* polymorphisms and hepatitis B infection in a brazilian population

OBJECTIVE

The aim of the present study was to determine the genotype association for alleles of class II human leukocyte antigens (HLA) in the DRB1* locus among blood donors at the Fundação Hemope (Brazil) infected by or immunized for the hepatitis B virus (HBV).

METHODS

A case-control study was performed, comprising a group of individuals infected by HBV and a control group of immunized individuals at a proportion of 1:4. Blood samples were taken for the HLA typing of the DRB1* locus. Univariate and multivariate analyses were performed for the assessment of associations between the categorical variables using the chi-squared test and Fisher's exact test.

RESULTS

A total of 320 blood donors were analyzed (241 males [75%] and 79 females [25%] with a mean age of 39 years). The case group consisted of 64 HBV-infected donors and the control group was composed of 256 HBV-immunized donors. The multivariate analysis stratified by gender revealed that the DRB1*09 allele was associated with infected male donors (p = 0.016) and the DRB1*08 allele was associated with infected donors aged 39 years or younger (p = 0.031).

CONCLUSION

The results of the present study reveal that younger blood donors and male blood donors who respectively exhibit the DRB1*08 and DRB1*09 alleles are more susceptible to intensification of HBV infection.

Genetic variants associated with susceptibility to mother-to-child transmission of hepatitis B virus

OBJECTIVE

The mechanisms of immune tolerance to hepatitis B virus (HBV) in children infected perinatally or early in infancy still remain unclarified. We aimed to study the genetic variants of immune factors implicated in viral-host interaction in children who were born to HBV-positive mothers and who had different clinical outcome.

METHODS

Mannose-binding lectin gene (mbl2) codon 54, codon 57, and promoter 221 variants, tumor necrosis factor α (TNF-α) 308G/A, and vitamin D receptor (VDR) ApaI and TaqI genotypes were analyzed in three groups of children born to HBV-positive mothers: children with chronic infection (n=33), those with resolved infection (n=36), and those naive for HBV (n=33).

RESULTS

TNF-α -308G allele frequency was found to be increased in children with chronic infection compared with children who were not affected by HBV [risk ratio (RR) 1.12, 95% confidence interval (CI) 1.0-1.25; P=0.050]. The VDR ApaI A allele tended to be more frequent in children with chronic infection than in those with resolved HBV infection (RR 1.27, 95% CI 0.95-1.67; P=0.071). The VDR ApaI α allele in ApaI and TaqI joint haplotype αT was more frequent in children with resolved infection than in those with chronic infection (RR 1.74, 95% CI 0.97-3.13; P=0.049).

CONCLUSION

Our results suggest that TNF-α and vitamin D pathways may be involved in the susceptibility to and outcome of HBV infection acquired early in life.

An algorithm for risk assessment and intervention of mother to child transmission of hepatitis B virus

BACKGROUND & AIMS

Despite immunoprophylaxis, mother to child transmission (MTCT) of hepatitis B virus (HBV) still occurs in infants born to hepatitis B surface antigen (HBsAg)-positive mothers. We analyzed methods of risk assessment and interventions for MTCT.

METHODS

We reviewed 63 articles and abstracts published from 1975-2011 that were relevant to MTCT; articles were identified using the PubMed bibliographic database.

RESULTS

Administration of HB immunoglobulin and HB vaccine to infants at birth (within 12 hours), followed by 2 additional doses of vaccines within 6-12 months, prevented approximately 95% of HBV transmission from HBsAg-positive mothers to their infants. However, HBV was still transmitted from 8%-30% of mothers with high levels of viremia. It is important to assess the risk for MTCT and identify mothers who are the best candidates for intervention. The most important risk factor is maternal level of HBV DNA >200,000 IU (10(6) copies)/mL; other factors include a positive test result for the HB e antigen, pregnancy complications such as threatened preterm labor or prolonged labor, and failure of immunoprophylaxis in prior children. Antiviral therapy during late stages of pregnancy is the most effective method to reduce transmission from mothers with high levels of viremia, but elective cesarean section might also be effective. Antepartum administration of HB immunoglobulin, giving infants a double dose of HB vaccine, or avoiding breastfeeding had no impact on MTCT.

CONCLUSIONS

HBsAg-positive mothers should be assessed for risk of MTCT, and infants should receive immunoprophylaxis. Pregnant women with levels of HBV DNA >200,000 IU/mL should be considered for strategies to reduce the risk for MTCT. We propose an algorithm for risk assessment and patient management that is based on a review of the literature and the opinion of a panel of physicians with expertise in preventing MTCT.

Hepatitis B Virus Infection during Pregnancy: Transmission and Prevention

Hepatitis B virus (HBV) infection is a global public health problem. In endemic areas, HBV infection occurs mainly during infancy and early childhood, with mother to child transmission (MTCT) accounting for approximately half of the transmission routes of chronic HBV infections. Prevention of MTCT is an essential step in reducing the global burden of chronic HBV. Natal transmission accounts for most of MTCT, and providing immunoprophylaxis to newborns is an excellent way to block natal transmission. Prenatal transmission is responsible for the minority of MTCT not preventable by immunoprophylaxis. Because of the correlation between prenatal transmission and the level of maternal viremia, some authors find it sound to offer lamivudine in women who have a high viral load (more than 8 to 9 log 10 copies/mL). In addition to considerations regarding the transmission of HBV to the child, the combination of HBV infection and pregnancy raises several unique management issues. Chronic HBV infection during pregnancy is usually mild but may flare after delivery or with discontinuing therapy. Management of chronic HBV infection in pregnancy is mostly supportive with antiviral medications indicated in a small subset of HBV infected women with rapidly progressive chronic liver disease.

Hepatitis B virus acquisition and pathogenesis in childhood: host genetic determinants

The clinical course of hepatitis B virus (HBV) infection varies from spontaneous recovery to chronic persistent infection leading to severe liver injury. Mounting evidence has recently highlighted the influence of host genotype in the complex interplay between viral and host factors. Studies in adults have suggested the existence of a genetic predisposition to HBV infection secondary to certain defects in the host response. These defects include opsonic deficiency, compromised antigen processing and presentation by human leucocyte antigen variations, attenuated T- and B-cell response, impaired cytokine and chemokine release, and production of receptors for several pertinent factors such as vitamin D and estrogen. By contrast, little is known about the genetic factors involved in the susceptibility to HBV transmission in early childhood. Herein, we review the literature regarding the association between host genetics and susceptibility to primary HBV infection, and we discuss the prospects of investigation in this field. A better understanding of HBV infection immunopathogenesis in the critical period of infancy may allow the development of optimal and innovative prevention and treatment.

Pregnancy and chronic hepatitis B virus infection

The combination of chronic hepatitis B virus (HBV) infection and pregnancy presents unique management questions. Aspects of care that need to be considered include effects of hepatitis B on pregnancy, effects of pregnancy itself on the course of hepatitis B infection, treatment of hepatitis B during pregnancy and prevention of mother-to-infant transmission. Chronic HBV infection is usually mild in pregnant women, but may flare shortly after delivery. Effect of HBV infection on pregnancy outcomes are generally favorable, but may depend on severity of liver disease. Mother-to-infant transmission can be minimized by current immunoprophylaxis strategies, however, high levels of viremia in mothers may be a factor in the small but reproducible failure rate of current immunoprophylaxis strategies. Use of antivirals during pregnancy needs to be individualized. Careful planning and management of pregnancy must be done among patients with chronic HBV infection.

Molecular characteristics and stages of chronic hepatitis B virus infection

Hepatitis B virus (HBV) is a common viral pathogen that causes a substantial health burden worldwide. Remarkable progress has been made in our understanding of the natural stages of chronic HBV infection. A dynamic balance between viral replication and host immune response is pivotal to the pathogenesis of liver disease. Knowledge of the HBV genome organization and replication cycle can unravel HBV genotypes and molecular variants, which contribute to the heterogeneity in outcome of chronic HBV infection. Most HBV infections are spontaneously resolved in immunocompetent adults, whereas they become chronic in most neonates and infants at a great risk of developing complications such as cirrhosis and hepatocellular carcinoma (HCC). Those with chronic HBV infection may present in one of the four phases of infection: immune tolerance, immune clearance [hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB)], inactive carrier state, and reactivation (HBeAg-negative CHB). Understanding the dynamic nature of chronic HBV infection is crucial in the management of HBV carriers. Long-term monitoring and optimal timing of antiviral therapy for chronic HBV infection help to prevent progression of HBV-related liver disease to its later stage, particularly in patients with higher risk markers of HCC, such as serum DNA concentration, HBeAg status, serum aminotransferase, HBV genotypes, and pre-core or core mutants.