The Association of Pre-S/S Gene Mutations and Hepatitis B Virus Vertical Transmission

Latest insights into the epidemiology, characteristics, and therapeutic strategies of chronic hepatitis B patients in indeterminate phase

As a hepatotropic virus, hepatitis B virus (HBV) can establish a persistent chronic infection in the liver, termed, chronic hepatitis B (CHB), which causes a series of liver-related complications, including fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). HCC with HBV infection has a significantly increased morbidity and mortality, whereas it could be preventable. The current goal of antiviral therapy for HBV infection is to decrease CHB-related morbidity and mortality, and achieve sustained suppression of virus replication, which is known as a functional or immunological cure. The natural history of chronic HBV infection includes four immune phases: the immune-tolerant phase, immune-active phase, inactive phase, and reactivation phase. However, many CHB patients do not fit into any of these defined phases and are regarded as indeterminate. A large proportion of indeterminate patients are only treated with dynamic monitoring rather than recommended antiviral therapy, mainly due to the lack of definite guidelines. However, many of these patients may gradually have significant liver histopathological changes during disease progression. Recent studies have focused on the prevalence, progression, and carcinogenicity of indeterminate CHB, and more attention has been given to the prevention, detection, and treatment for these patients. Herein, we discuss the latest understanding of the epidemiology, clinical characteristics, and therapeutic strategies of indeterminate CHB, to provide avenues for the management of these patients.

Vertical Transmission of Hepatitis B Virus-An Update

Hepatitis B virus (HBV) infection is a major public health problem in the world. Approximately 296 million people are chronically infected. In endemic areas, vertical transmission is a common route of transmission. There are several strategies for the prevention of HBV vertical transmission, such as antiviral treatment during the third trimester of pregnancy and immunoprophylaxis to newborns that includes the administration of hepatitis B immune globulin (HBIG) and an HBV vaccine. Despite this, immunoprophylaxis failure can occur in up to 30% of infants born to HBeAg-positive mothers and/or with high viral load. Therefore, management and prevention of HBV vertical transmission is of paramount significance. In this article, we provided a review of the epidemiology, mechanisms of pathogenesis and risk factors of vertical transmission, as well as the strategies implemented to prevent the infection.

Analysis of S gene characteristic sequences and changes in properties of protein expression in HBV ASCs with low-level HBsAg

Objective

We detected the serum HBsAg immune complex (HBsAg-CIC) and sequenced the HBV S gene in these patients to reveal the association between sustained low-level expression of HBsAg and mutated S gene sequence characteristics, protein function changes, and HBsAg immune complex formation.

Methods

A total of 204 samples were collected and divided into high-level (n = 60, HBsAg level >10 IU/ml) and low-level (n = 144, HBsAg level ≤ 10 IU/ml) HBsAg groups. The clinical and epidemiological data of the two groups were statistically compared. According to different serological patterns and genotypes, the HBsAg-CIC results of the high-level and low-level HBsAg groups were divided into different subgroups, and then the HBsAg-CIC positive rates among different subgroups were compared. We sequenced the S gene of HBV from the two groups and identified the relevant mutations in the MHR of the S gene. In addition, we compared the changes in HBsAg protein properties and functions after hot spot mutation in the MHR of the S gene.

Results

Comparing the positive rates of HBsAg-CIC under different serological patterns and genotypes in the two groups, the HBsAg-CIC positive rate was higher in the low-level HBsAg group. Moreover, there was weak correlation between HBsAg-CIC and HBsAg or HBV DNA in both groups (r = 0.32, 0.27, 0.41, 0.48; P < 0.05). Sequencing of S gene in the two groups, showed that the hot-spot mutations were T126A, M133L/T/S, and F134L/T/I in MHR of S gene of genotype B, and hot-spot mutations were Q101R and I126S/T in MHR of S gene of genotype C. Additionally, the positive rate of MHR mutation in the S gene from HBsAg-CIC positive patients was higher in the low-level HBsAg group.

Conclusion

The host immune process of clearing HBV seems to have multiple site mutations in MHR, which changes the physicochemical properties and functions of HBsAg and intensifies the formation of HBsAg-CIC, thus avoiding the effective recognition of HBsAg by the host and resulting in immune tolerance between the host and HBV, which may be one of the formation mechanisms of sustained low-level expression of HBsAg in the serum of HBV-infected persons.

Hepatitis B virus genotype is an independent prognostic factor of telbivudine and tenofovir treatment in hepatitis B surface antigen-positive pregnant women

To investigate whether HBV genotype influences the effect of tenofovir and telbivudine on HBV DNA and RNA levels in HBsAg-positive pregnant women. This was a retrospective study of 74 HBsAg-positive pregnant women in Guizhou of China. All patients were treated with telbivudine or tenofovir from 12 weeks of pregnancy and HBV infection to the date of delivery. Blood samples were collected at 12-24, 28-32, and 36-40 weeks of pregnancy for the measurement of genotype, HBsAg, hepatitis B e antigen (HBeAg), HBV DNA, HBV RNA, and liver function, including alanine transaminase, aspartate transaminase, total bilirubin, total bile acids, cholinesterase, alkaline phosphatase (ALP), and gamma-glutamyl transferase. All women with HBsAg were followed up. The HBV genotype was B in 64.9% and C in 35.1%. There were 37 patients of telbivudine and tenofovir group respectively. The telbivudine and tenofovir groups showed no differences in demographic and clinical characteristics, including liver function tests, HBsAg, HBeAg, log10(HBV DNA), and log10(HBV RNA). Compared with baseline (12-24 weeks), telbivudine group showed a significant increase in ALP and significant reductions in HBsAg, HBeAg, log10(HBV DNA), and log10(HBV RNA) at 36-40 weeks (p < .05). Tenofovir group exhibited a significant increase in ALP and significant reductions in HBeAg, log10(HBV DNA), and log10(HBV RNA) at 36-40 weeks, compared with baseline (p < .05). HBV genotype (B vs. C) was independently associated with HBV DNA change after therapy (p = .005). In telbivudine group, log10 (HBV DNA) increased from 3.38 (2.00-7.30) to 7.43 (4.68-8.70). In tenofovir group, log10 (HBV DNA) decreased from 7.52 (3.32-8.70) to 2.98 (2.00-5.01). HBV genotype was independently associated with HBV DNA change response to telbivudine or tenofovir in pregnant women with hepatitis B. These findings might be helpful for risk assessment regarding vertical transmission of HBV in HBeAg-positive mothers treated with nucleos(t)ide analogues.

Using Quasispecies Patterns of Hepatitis B Virus to Predict Hepatocellular Carcinoma With Deep Sequencing and Machine Learning

BACKGROUND

Hepatitis B virus (HBV) infection is one of the main leading causes of hepatocellular carcinoma (HCC) worldwide. However, it remains uncertain how the reverse-transcriptase (rt) gene contributes to HCC progression.

METHODS

We enrolled a total of 307 patients with chronic hepatitis B (CHB) and 237 with HBV-related HCC from 13 medical centers. Sequence features comprised multidimensional attributes of rt nucleic acid and rt/s amino acid sequences. Machine-learning models were used to establish HCC predictive algorithms. Model performances were tested in the training and independent validation cohorts using receiver operating characteristic curves and calibration plots.

RESULTS

A random forest (RF) model based on combined metrics (10 features) demonstrated the best predictive performances in both cross and independent validation (AUC, 0.96; accuracy, 0.90), irrespective of HBV genotypes and sequencing depth. Moreover, HCC risk scores for individuals obtained from the RF model (AUC, 0.966; 95% confidence interval, .922-.989) outperformed α-fetoprotein (0.713; .632-.784) in distinguishing between patients with HCC and those with CHB.

CONCLUSIONS

Our study provides evidence for the first time that HBV rt sequences contain vital HBV quasispecies features in predicting HCC. Integrating deep sequencing with feature extraction and machine-learning models benefits the longitudinal surveillance of CHB and HCC risk assessment.

Maternal viral load and hepatitis B virus mother-to-child transmission risk: A systematic review and meta-analysis

AIM

The aim of this study was to assess the relationship between maternal viral load and mother-to-child transmission (MTCT) risk in hepatitis B envelope antigen (HBeAg)-positive mothers.

METHODS

PubMed and Web of Science were systematically searched. We compared MTCT incidence between maternal hepatitis B virus (HBV)-DNA-positive and HBV-DNA-negative groups. We also examined the dose-response effect of this relationship.

RESULTS

Twenty-one studies with 10 142 mother-child pairs were included in the studies. The mean MTCT incidence was 13.1% in the maternal HBV-DNA-positive group, compared with 4.2% in the negative group. The summary MTCT odds ratio of maternal HBV-DNA positive compared with negative was 9.895 (95% confidence interval [CI], 5.333 to 18.359; Z = 7.27, P < 0.00001) by random-effects model. In maternal HBV-DNA <6 log10 copies/mL, 6-8 log10 copies/mL, and >8 log₁₀ copies/mL level stratifications, the pooled MTCT incidences were 2.754% (95% CI, 1.198-4.310%; Z = 3.47, P = 0.001), 9.932% (95% CI, 6.349-13.516%; Z = 5.43, P < 0.00001), and 14.445% (95% CI, 8.317-20.572%; Z = 4.62, P < 0.00001), respectively. A significant linear dose-response association was found between maternal viral load and MTCT risk, with the points estimate of increased MTCT risk 2.705 (95% CI, 1.808-4.047) at 6 log10 copies/mL compared with reference (3 log10 copies/mL), and 7.316 (95% CI, 3.268-16.378) at 9 log₁₀  copies/mL. A significant non-linear dose-response association was also found between maternal viral load and HBV MTCT risk (model χ²  = 23.43, P < 0.00001).

CONCLUSION

Our meta-analysis indicated that maternal viral load was an important risk factor for MTCT in HBeAg-positive mothers, and maternal viral load was dose-dependent with HBV MTCT incidence.

Three types of preS1 start codon deletion variants in the natural course of chronic hepatitis B infection

BACKGROUND AND AIM

Naturally occurring hepatitis B virus variants carrying a deletion in the preS1 start codon region may evolve during long-lasting virus-host interactions in chronic hepatitis B (CHB). The aim of this study was to determine the immune phase-specific prevalent patterns of preS1 start codon deletion variants and related factors during the natural course of CHB.

METHODS

A total of 399 CHB patients were enrolled. Genotypic analysis of three different preS1 start codon deletion variants (classified by deletion size: 15-base pair [bp], 18-bp, and 21-bp deletion variants) was performed.

RESULTS

PreS1 start codon deletion variants were detected in 155 of 399 patients (38.8%). The predominant variant was a 15-bp deletion in the immune-tolerance phase (18/50, 36%) and an 18-bp deletion in the immune-clearance phase (69/183, 37.7%). A 21-bp deletion was the predominant variant in the low replicative phase (3/25, 12.0%) and reactivated hepatitis Be antigen (HBeAg)-negative phase (22/141, 15.6%). The 15-bp and 18-bp deletion variants were more frequently found in HBeAg-positive patients (P < 0.010 and P < 0.001, respectively), whereas the 21-bp deletion variant was more frequently found in HBeAg-negative patients (P < 0.001). On multiple logistic regression analyses, the 21-bp deletion variant was independently associated with liver cirrhosis (P = 0.006), and the 15-bp deletion variant was significantly related to an incomplete response to antiviral agents (P = 0.012).

CONCLUSIONS

The predominant type of preS1 start codon deletion variants changes according to the immune phases of CHB infection, and each variant type is associated with different clinical parameters. PreS1 start codon deletion variants might interact with the host immune response differently according to their variant types.