Review on hepatitis B virus precore/core promoter mutations and their correlation with genotypes and liver disease severity

Predictive Risk Factors and Scoring Systems Associated with the Development of Hepatocellular Carcinoma in Chronic Hepatitis B

Chronic hepatitis B (CHB) infection constitutes a leading cause of hepatocellular carcinoma (HCC) development. The identification of HCC risk factors and the development of prognostic risk scores are essential for early diagnosis and prognosis. The aim of this observational, retrospective study was to evaluate baseline risk factors associated with HCC in CHB. Six hundred thirty-two consecutive adults with CHB (n = 632) [median age: 46 (IQR: 24)], attending the outpatients' Hepatology clinics between 01/1993-09/2020 were evaluated. Core promoter mutations and cirrhosis-HCC (GAG-HCC), Chinese University-HCC (CU-HCC), risk estimation for hepatocellular carcinoma in chronic hepatitis B (REACH-B), Fibrosis-4 (FIB-4), and Platelet Age Gender-HBV (PAGE-B) prognostic scores were calculated, and receiver operating curves were used to assess their prognostic performance. HCC was developed in 34 (5.38%) patients. In the multivariable Cox regression analysis, advanced age (HR: 1.086, 95% CI: 1.037-1.137), male sex (HR: 7.696, 95% CI: 1.971-30.046), alcohol abuse (HR: 2.903, 95% CI: 1.222-6.987) and cirrhosis (HR: 21.239, 95% CI: 6.001-75.167) at baseline were independently associated with the development of HCC. GAG-HCC and PAGE-B showed the highest performance with c-statistics of 0.895 (95% CI: 0.829-0.961) and 0.857 (95% CI: 0.791-0.924), respectively. In the subgroup of patients with cirrhosis, the performance of all scores declined. When treated and untreated patients were studied separately, the discriminatory ability of the scores differed. In conclusion, HCC development was independently associated with advanced age, male sex, alcohol abuse, and baseline cirrhosis among a diverse population with CHB. GAG-HCC and PAGE-B showed high discriminatory performance to assess the risk of HCC development in these patients, but these performances declined in the subgroup of patients with cirrhosis. Further research to develop scores more specific to certain CHB subgroups is needed.

Characterization of mutations in hepatitis B virus DNA isolated from Japanese HBsAg-positive blood donors in 2021 and 2022

Missense mutations in certain small envelope proteins diminish the efficacy of antibodies. Consequently, tracking the incidence and types of vaccine-escape mutations (VEMs) was crucial both before and after the introduction of universal hepatitis B vaccination in Japan in 2016. In this study, we isolated hepatitis B virus (HBV) DNA from 58 of 169 hepatitis B surface antigen (HBsAg)-positive blood samples from Japanese blood donors and determined the nucleotide sequence encoding the small envelope protein. DNA from six (10%) of the samples had VEMs, but no missense mutations, such as G145R, were detected. Complete HBV genome sequences were obtained from 29 of the 58 samples; the viral genotype was A1 in one (3%), A2 in three (10%), B1 in nine (31%), B2 in five (17%), B4 in one (3%), and C2 in 10 (34%) samples. Tenofovir-resistance mutations were detected in two (7%) samples. In addition, several core promoter mutations, such as 1762A>T and 1764G>A, and a precore nonsense mutation, 1986G>A, which are risk factors for HBV-related chronic liver disease, were detected. These findings provide a baseline for future research and highlight the importance of ongoing monitoring of VEMs and drug resistance mutations in HBV DNA from HBsAg-positive blood donors without HBV antibodies.

Hepatitis B virus genotypes in precision medicine of hepatitis B-related hepatocellular carcinoma: Where we are now

Hepatitis B virus (HBV) infection is a major player in chronic hepatitis B that may lead to the development of hepatocellular carcinoma (HCC). HBV genetics are diverse where it is classified into at least 9 genotypes (A to I) and 1 putative genotype (J), each with specific geographical distribution and possible different clinical outcomes in the patient. This diversity may be associated with the precision medicine for HBV-related HCC and the success of therapeutical approaches against HCC, related to different pathogenicity of the virus and host response. This Editorial discusses recent updates on whether the classification of HBV genetic diversity is still valid in terms of viral oncogenicity to the HCC and its precision medicine, in addition to the recent advances in cellular and molecular biology technologies.

Distribution and Clinical Significance of Hepatitis B virus A1762T/G1764A Double Mutation in Chronic Hepatitis B Patients: A Cross-Sectional Study

BACKGROUND

Chronic hepatitis B (CHB) is well-known as a major risk for liver cirrhosis and hepatocellular carcinoma (HCC). The A1762T/G1764A double mutation in the hepatitis B virus genome affects the production of HBe antigen and is established as a predictive marker for progression to HCC. Thus, this study aimed to investigate the prevalence and clinical significance of the mutation in Thai CHB patients.

METHODS

 A cross-sectional study was conducted in 78 Thai CHB patients who were assessed for hepatitis B profiles, HBsAg, HBeAg and anti-HBeAg, transaminitis, liver fibrosis defined by FIB-4 (FIB-4) score and AST to platelet ratio index (APRI), alpha-fetoprotein (AFP) and active hepatitis B status. HBV A1762T/G1764A mutation was examined by SYBR Green I Real-time PCR. Chi-square and Mann-Whiney U tests were performed to determine the association between the mutation and variables.

RESULTS

The prevalence of patients infected with the A1762T/G1764A mutation was 44.9%. The mutation was associated with HBeAg status (p=0.027) and HBsAg levels (p=0.008), transaminitis (p=0.011), and active hepatitis B (p=0.037), but not liver fibrosis markers, FIB-4 score and APRI, and AFP. Binary logistic regression identified the mutation as a predictive factor of active hepatitis B (OR 3.5, 95%CI, 1.1-11.3, p=0.037). Patients infected with the mutant exhibited significantly higher levels of HBsAg (p=0.011) and HBV viral load (p=0.047), but lower levels of HBeAg (p=0.12) than those infected with the wild-type HBV.

CONCLUSION

The data indicate the high prevalence of the A1762T/G1764A mutation and its significant association with the severity of Thai CHB patients and the HBV mutation is proposed as a predictive marker of active hepatitis B status in CHB patients.

The Epidemiology, Transmission, Genotypes, Replication, Serologic and Nucleic Acid Testing, Immunotolerance, and Reactivation of Hepatitis B Virus

The epidemiology of Hepatitis B virus (HBV) has drastically changed in recent decades due to public health initiatives, including universal infant vaccination programs,urbanization driving global travel, and migration patterns. Despite screening of pregnant women and newborns significantly reducing the rate of perinatal transmission in certain parts of the world, other, perhaps more uncommon, routes (e.g., parenteral) have led to outbreaks in specific areas affected by the opioid epidemic and injection drug use. Although our current understanding of the effect of genetic variants of HBV is lacking, we review current knowledge and patterns of genetic variants with geographical predominance, pathophysiology, and clinical manifestations. Serologic and molecular markers are used to screen, identify phase and activity of infection, and monitor response to antivirals and/or reactivation. This review will provide the most up-to-date summary of the epidemiology, transmission, genotype, replication, and current methods of screening to follow the various phases of HBV, including immunotolerance and reactivation.

Impact of core protein naturally selected mutants associated with HBeAg-negative status in HBV biosynthesis

Hepatitis B e antigen (HBeAg) loss represents a late stage of chronic hepatitis B virus (HBV) infection associated with a drastic decrease in HBV-DNA, a lower risk of disease progression, and the occurrence of several mutations in the preCore/core region. However, the underlying mechanisms supporting the downregulation of viral replication have yet to be elucidated. In the present study, the analysis of the frequency of subgenotype D1 core protein (HBc) mutations associated with HBeAg status revealed a higher mutation rate in HBeAg-negative sequences compared to HBeAg-positive ones. Particularly, 22 amino acids exhibited a higher frequency of mutation in HBeAg-negative sequences, while the remaining residues showed a high degree of conservation. Subsequently, the assessment of HBc mutants derived from HBeAg-negative patients in viral structure and replicative capacity revealed that HBc mutations have the ability to modulate the subcellular localization of the protein (either when the protein was expressed alone or in the context of viral replication), capsid assembly, and, depending on specific mutation patterns, alter covalently closed circular DNA (cccDNA) recycling and up- or downregulate viral replication. In conclusion, HBc mutations associated with HBeAg-negative status impact on various stages of the HBV life cycle modulating viral replication during the HBeAg-negative stage of infection.

HBV precore G1896A mutation promotes growth of hepatocellular carcinoma cells by activating ERK/MAPK pathway

Chronic hepatitis B virus (HBV) infection is one of the leading causes of hepatocellular carcinoma (HCC). The HBV genome is prone to mutate and several variants are closely related to the malignant transformation of liver disease. G1896A mutation (G to A mutation at nucleotide 1896) is one of the most frequently observed mutations in the precore region of HBV, which prevents HBeAg expression and is strongly associated with HCC. However, the mechanisms by which this mutation causes HCC are unclear. Here, we explored the function and molecular mechanisms of the G1896A mutation during HBV-associated HCC. G1896A mutation remarkably enhanced the HBV replication in vitro. Moreover, it increased tumor formation and inhibited apoptosis of hepatoma cells, and decreased the sensitivity of HCC to sorafenib. Mechanistically, the G1896A mutation could activate ERK/MAPK pathway to enhanced sorafenib resistance in HCC cells and augmented cell survival and growth. Collectively, our study demonstrates for the first time that the G1896A mutation has a dual regulatory role in exacerbating HCC severity and sheds some light on the treatment of G1896A mutation-associated HCC patients.

HBV Infection and Host Interactions: The Role in Viral Persistence and Oncogenesis

Hepatitis B virus (HBV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Despite the advent of vaccines and potent antiviral agents able to suppress viral replication, recovery from chronic HBV infection is still an extremely difficult goal to achieve. Complex interactions between virus and host are responsible for HBV persistence and the risk of oncogenesis. Through multiple pathways, HBV is able to silence both innate and adaptive immunological responses and become out of control. Furthermore, the integration of the viral genome into that of the host and the production of covalently closed circular DNA (cccDNA) represent reservoirs of viral persistence and account for the difficult eradication of the infection. An adequate knowledge of the virus-host interaction mechanisms responsible for viral persistence and the risk of hepatocarcinogenesis is necessary for the development of functional cures for chronic HBV infection. The purpose of this review is, therefore, to analyze how interactions between HBV and host concur in the mechanisms of infection, persistence, and oncogenesis and what are the implications and the therapeutic perspectives that follow.

Locked nucleic acid real-time polymerase chain reaction method identifying two polymorphisms of hepatitis B virus genotype C2 infections, rt269L and rt269I

BACKGROUND

The presence of two distinct hepatitis B virus (HBV) Pol RT polymorphisms, rt269L and rt269I, could contribute to the unique clinical or virological phenotype of HBV genotype C2. Therefore, a simple and sensitive method capable of identifying both types in chronic hepatitis B (CHB) patients infected with genotype C2 should be developed.

AIM

To develop a novel simple and sensitive locked nucleic acid (LNA)-real time-polymerase chain reaction (RT-PCR) method capable of identifying two rt269 types in CHB genotype C2 patients.

METHODS

We designed proper primer and probe sets for LNA-RT-PCR for the separation of rt269 types. Using synthesized DNAs of the wild type and variant forms, melting temperature analysis, detection sensitivity, and endpoint genotyping for LNA-RT-PCR were performed. The developed LNA-RT-PCR method was applied to a total of 94 CHB patients of genotype C2 for the identification of two rt269 polymorphisms, and these results were compared with those obtained by a direct sequencing protocol.

RESULTS

The LNA-RT-PCR method could identify two rt269L and rt269I polymorphisms of three genotypes, two rt269L types [‘L1’ (WT) and ‘L2’] and one rt269I type (‘I’) in single (63 samples, 72.4%) or mixed forms (24 samples, 27.6%) in 87 (92.6% sensitivity) of 94 samples from Korean CHB patients. When the results were compared with those obtained by the direct sequencing protocol, the LNA-RT-PCR method showed the same results in all but one of 87 positive detected samples (98.9% specificity).

CONCLUSION

The newly developed LNA-RT-PCR method could identify two rt269 polymorphisms, rt269L and rt269I, in CHB patients with genotype C2 infections. This method could be effectively used for the understanding of disease progression in genotype C2 endemic areas.

Acute and chronic HBV infection in central Argentina: High frequency of sub-genotype F1b, low detection of clinically relevant mutations and first evidence of HDV

Introduction

Genomic analysis of hepatitis B virus (HBV) identifies phylogenetic variants, which may lead to distinct biological and clinical behaviors. The satellite hepatitis D virus (HDV) may also influence clinical outcomes in patients with hepatitis B. The aim of this study was to investigate HBV genetic variants, including clinically relevant mutations, and HDV infection in acute and chronic hepatitis B patients in central Argentina.

Methods

A total of 217 adult HBV infected patients [acute (AHB): n = 79; chronic (CHB): n = 138] were studied; 67 were HBV/human immunodeficiency virus (HIV) coinfected. Clinical and demographic data were obtained from medical records. Serological markers were determined. Molecular detection of HBV and HDV was carried out by RT-Nested PCR, followed by sequencing and phylogenetic analysis.

Results

Overall, genotype (gt) F [sub-genotype (sgt) F1b] was the most frequently found. In AHB patients, the gts/sgts found were: F1b (74.7%) > A2 (13.9%) > F4 (7.6%) > C (2.5%) > A1 (1.3%). Among CHB patients: F1b (39.1%) > A2 (23.9%) > F4 (18.2%) > D (9.4%) > C and F6 (3.6% each) > A1, A3 and B2 (0.7% each). The distribution of sgt A2 and gt D was significantly different between HBV mono and HBV/HIV coinfected patients [A2: 15.9% vs. 35.7% (p < 0.05), respectively and D: 14.6% vs. 1.8% (p < 0.05), respectively]. Mutation frequency in basal core promoter/pre-Core (BCP/pC) region was 35.5% (77/217) [AHB: 20.3% (16/79), CHB: 44.2% (61/138)]. In the open reading frame (ORF) S, mutations associated with vaccine escape and diagnostic failure were detected in 7.8% of the sequences (17/217) [AHB: 3.8% (3/79), CHB: 10.1% (14/138)]. ORF-P amino acid substitutions associated with antiviral resistance were detected in 3.2% of the samples (7/217) [AHB: 1.3% (1/79), CHB 4.3%, (6/138)]. The anti-HDV seropositivity was 5.2% (4/77); one sample could be sequenced, belonging to gt HDV-1 associated with sgt HBV-D3.

Discussion

We detected an increase in the circulation of genotype F in Central Argentina, particularly among AHB patients, suggesting transmission advantages over the other genotypes. A low rate of mutations was detected, especially those with antiviral resistance implications, which is an encouraging result. The evidence of HDV circulation in our region, reported for the first time, alerts the health system for its search and diagnosis.