Amino acid polymorphism in the reverse transcriptase region of hepatitis B virus and the relationship with nucleos(t)ide analogues treatment for preventing mother-to-infant transmission

Reduction of the occurrence of occult HBV infection in infants by increasing the dose of hepatitis B vaccine: a large prospective cohort study

Occult hepatitis B virus (HBV) infection (OBI) has been observed among infants born to hepatitis B surface antigen (HBsAg)-positive mothers despite successful immunoprophylaxis. This study enrolled 549 infants [349 infants received a 10μg/dose of hepatitis B vaccine (HepB), and 200 infants received 20μg/dose HepB] born to HBsAg-positive mothers with HBV DNA load >6log₁₀IU/mL. The anti-HBs levels in the 10μg group were significantly lower than that in the 20μg group both at 7 [652.48 (564.05-754.82) vs. 1541.72 (1268.69-1873.51) mIU/mL, P<0.001] and 12 months old [257.44 (220.29-300.88) vs. 1073.41 (839.27-1372.78) mIU/mL, P<0.001]. The OBI incidence in the 10μg group was significantly higher than that in the 20μg group at both 7 [21.55% (25/116) vs. 7.56% (9/119), P=0.002] and 12 months old [17.07% (14/82) vs. 6.90% (6/87), P=0.041]. OBI incidence in infants with anti-HBs levels <100mIU/mL was higher than that of those with anti-HBs ≥100mIU/mL [35.71% (5/14) vs. 13.12% (29/221), P=0.036]. This study showed that increasing the immunisation dose from 10μg to 20μg significantly improved anti-HBs levels and decreased OBI incidence in infants with a high maternal viral load. We recommend 20μg HepB to treat this high-risk population.

Quasispecies characteristic in "a" determinant region is a potential predictor for the risk of immunoprophylaxis failure of mother-to-child-transmission of sub-genotype C2 hepatitis B virus: a prospective nested case-control study

OBJECTIVE

This study was performed to explore the correlation between the characteristics of hepatitis B virus (HBV) quasispecies in HBV-infected pregnant women and the risk of immunoprophylaxis failure for their infants.

DESIGN

In this prospective nested case-control study, the characteristics of HBV quasispecies in mothers whose infants were immunoprophylaxis success (control group) and those whose infants were immunoprophylaxis failure (case group) were analysed by the clone-based sequencing of full-length HBV genome and next-generation sequencing (NGS) of "a" determinant region, and were compared between the two groups.

RESULTS

The quasispecies characteristics including mutant frequency, Shannon entropy and mean genetic distance at amino acid level of "a" determinant region were significantly lower in case group than that in control group, using the full-length HBV genome clone-based sequencing assay. These results were confirmed by NGS assay. Notably, we discovered that the differences were also significant at nucleotide level by NGS assay. Furthermore, the risk of immunoprophylaxis failure could be predicted by analysing the three HBV quasispecies characteristics either at nucleotide level or at amino acid level of "a" determinant region, and the corresponding predictive values were tentatively set up.

CONCLUSIONS

HBV quasispecies with a more complex mutant spectrum in "a" determinant region might be more vulnerable to extinct through mother-to-child-transmission (MTCT). More importantly, analysing HBV quasispecies characteristics in pregnant women with high HBV DNA load might be helpful to predict the high-risk population of immunoprophylaxis failure, and consequently provide accurate intervention against MTCT of HBV.

Efficacy and safety of nucleos(t)ide analogues to prevent hepatitis B virus mother-to-child transmission in pregnant women with high viremia: real life practice from China

Purpose: To evaluate the efficacy and safety of nucleos(t)ide analogues, especially telbivudine (LdT) for the prevention of mother-to-child transmission (MTCT) of hepatitis B virus (HBV) in women with high viremia. Methods: We conducted a prospective, open-label, multicenter study of LdT for treating pregnant women having high viral loads of hepatitis B virus (HBV DNA>5 log₁₀ IU/mL) but normal levels of alanine aminotransferase (ALT). Maternal HBV DNA, HBV serologic status and ALT were measured at baseline, 4 weeks after therapy, before delivery, 4 weeks after delivery, and 12 weeks after delivery. Infant HBV serologic status and HBV DNA levels were measured at 7 months. We calculated the MTCT rate of LdT-treated and LdT-untreated groups and analyzed the efficacy and safety of LdT. Results: Ninety-one women (the treatment group) were treated with LdT, and twenty-one patients (the observation group) did not undergo antiviral therapy. The baseline HBV DNA levels were 8.15±0.82 log₁₀ IU/mL in the treatment group, and 8.09±1.04 log₁₀ IU/mL in the observation group. The MTCT rate was 0% in the treatment group, and 9.5% in the observation group (p=0.042). In the treatment group, HBV DNA levels were 5.02±0.74 log₁₀ IU/mL at one month after therapy, and 3.95±0.94 log₁₀ IU/mL before delivery. Both groups had significant differences from baseline levels in HBV DNA levels (p<0.001). In total, five patients had elevated ALT levels but without evidence of decompensate liver function. No severe adverse events or complications were observed in women or infants. Conclusions: For pregnant women with HBV DNA greater than 5 log₁₀IU/mL, LdT therapy was effective in reducing HBV MTCT. If serum HBV DNA was detectable at delivery, discontinuation of LdT immediately was found to be safe and rarely induced off-treatment hepatitis flare.

The maternal viral threshold for antiviral prophylaxis of perinatal hepatitis B virus transmission in settings with limited resources: A large prospective cohort study in China

BACKGROUND

Antiviral therapy has been documented to reduce perinatal transmission of hepatitis B virus (HBV) in highly viremic mothers. This large prospective cohort study conducted in China aims to delineate the maternal viral threshold for consideration of antiviral prophylaxis in settings with limited resources.

METHODS

A total of 1177 mother-infant pairs with positive maternal hepatitis B surface antigen (HBsAg) under current passive-active prophylaxis regimen were enrolled from community health centers in Jiangsu and Henan provinces, China. Maternal hepatitis B e antigen (HBeAg) status and viral load were tested at 36-40 weeks of gestation. Post-vaccination serologic testing was performed at 7 and 12 months of age.

RESULTS

HBeAg-positive mothers (419/1177; 35.6%) had significantly higher viral loads, compared with HBeAg-negative mothers (758/1177; 64.4%) (8.12 vs. 2.69 log IU/mL, p < .0001). Twenty infants, born to HBeAg-positive mothers with high viral loads (median, 8.38; range: 7.82-9.22 log IU/mL), were infected at 7 months of age. In contrast, none of the HBeAg-negative mothers transmitted HBV to their offspring. After adjustment for the other risk factor, a higher maternal viral load was significantly associated with a higher risk of transmission (adjusted odds ratio, 3.78; 95% confidence interval: 1.46-9.81; p = .006). The rates of passive-active immunoprophylaxis failure were 0.0% (0/789), 0.0% (0/27), 0.0% (0/32) and 6.1% (20/329) at maternal viral loads of <5, 5-6, 6-7 and ≥7 log IU/mL, respectively. The antibody to hepatitis B surface antigen (anti-HBs) response rate was 98.4% (1138/1157) at 7 months of age.

CONCLUSIONS

Results from this study indicate that the maternal viral threshold associated with perinatal transmission of HBV is 7 log IU/mL, which may be appropriate for consideration of antiviral prophylaxis in settings with limited resources.

Strategies to prevent mother-to-child transmission of hepatitis B

Mother-to-child transmission is the main way of hepatitis B virus (HBV) infection. Thus, blocking mother-to-child transmission is an important means to control the epidemic of HBV. However, the management of pregnant women with HBV still has many problems, such as the lack of uniform guidelines on the treatment. Although passive-active immunoprophylaxis, including hepatitis B immunoglobulin and hepatitis B virus vaccine, is widely used at birth to interrupt HBV transmission, mother-to-child transmission of HBV still occurs in some infants. In recent years nucleoside analog has been widely used in clinical practice. This paper summarizes and analyzes a variety of programs of blocking mother-to-child transmission, aiming to make strategies to prevent mother-to-child transmission of HBV more standardized and effective.

Prevalence of mutations in HBV DNA polymerase gene associated with nucleos(t)ide resistance in treatment-naive patients with Chronic Hepatitis B in Central China

Objective

There are a lot of disagreements in the studies on hepatitis B virus (HBV) DNA polymerase mutation rate associated with nucleos(t)ide analogues (NAs) in treatment-naive chronic hepatitis B (CHB) patients. This is the first study aimed to investigate the prevalence of spontaneous HBV resistance mutations in Central China.

Methods

This study included treatment-naive patients with CHB from June 2012 to May 2015 receiving care at the Institute of Liver Disease in Central China. All patients completed a questionnaire covering different aspects, such as family medical history, course of liver disease, medication history, alcohol use, among others. Mutations in HBV DNA polymerase associated with NAs resistance were detected using INNO-LiPA assay.

Results

269 patients were infected with HBV genotype B (81.4%), C (17.9%), and both B and C (0.7%). Mutations in HBV DNA polymerase were detected in 24 patients (8.9%) including rtM204I/V (n = 6), rtN236T (n = 5), rtM250V (n = 2), rtL180M (n = 2), rtT184G (n = 1), rtM207I (n = 1), rtS202I (n = 1), rtM204V/I & rtL180M (n = 5), and rtM204I & rtM250V (n = 1).

Conclusion

Spontaneous HBV resistance mutations in HBV DNA polymerase were found in treatment-naive patients with CHB in Central China. These findings suggest that we should analyze HBV DNA polymerase resistance mutation associated with NAs before giving antiviral therapy such as lamivudine (LAM), adefovir (ADV), and telbivudine (LdT).

Genetic variation of hepatitis B virus and its significance for pathogenesis

Hepatitis B virus (HBV) has a worldwide distribution and is endemic in many populations. Due to its unique life cycle which requires an error-prone reverse transcriptase for replication, it constantly evolves, resulting in tremendous genetic variation in the form of genotypes, sub-genotypes, and mutations. In recent years, there has been considerable research on the relationship between HBV genetic variation and HBV-related pathogenesis, which has profound implications in the natural history of HBV infection, viral detection, immune prevention, drug treatment and prognosis. In this review, we attempted to provide a brief account of the influence of HBV genotype on the pathogenesis of HBV infection and summarize our current knowledge on the effects of HBV mutations in different regions on HBV-associated pathogenesis, with an emphasis on mutations in the preS/S proteins in immune evasion, occult HBV infection and hepatocellular carcinoma (HCC), mutations in polymerase in relation to drug resistance, mutations in HBV core and e antigen in immune evasion, chronicalization of infection and hepatitis B-related acute-on-chronic liver failure, and finally mutations in HBV x proteins in HCC.