Next generation sequencing identifies baseline viral mutants associated with treatment response to pegylated interferon in HBeAg-positive chronic hepatitis B

Evolution and diversity of the hepatitis B virus genome: Clinical implications

Hepatitis B virus (HBV) infection remains a significant global health burden. The genetic variation of HBV is complex. HBV can be divided into nine genotypes, which show significant differences in geographical distribution, clinical manifestations, transmission routes and treatment response. In recent years, substantial progress has been made through various research methods in understanding the development, pathogenesis, and antiviral treatment response of clinical disease associated with HBV genetic variants. This progress provides important theoretical support for a deeper understanding of the natural history of HBV infection, virus detection, drug treatment, vaccine development, mother-to-child transmission, and surveillance management. This review summarizes the mechanisms of HBV diversity, discusses methods used to detect viral diversity in current studies, and the impact of viral genome variation during infection on the development of clinical disease.

Interferon and Hepatitis B: Current and Future Perspectives

Chronic hepatitis B virus (HBV) infection remains a major health burden worldwide for which there is still no effective curative treatment. Interferon (IFN) consists of a group of cytokines with antiviral activity and immunoregulatory and antitumor effects, that play crucial roles in both innate and adaptive immune responses. IFN-α and its pegylated form have been used for over thirty years to treat chronic hepatitis B (CHB) with advantages of finite treatment duration and sustained virologic response, however, the efficacy is limited and side effects are common. Here, we summarize the status and unique advantages of IFN therapy against CHB, review the mechanisms of IFN-α action and factors affecting IFN response, and discuss the possible improvement of IFN-based therapy and the rationale of combinations with other antiviral agents in seeking an HBV cure.

Mutational characterization of HBV reverse transcriptase gene and the genotype-phenotype correlation of antiviral resistance among Chinese chronic hepatitis B patients

Background and Aims: The drug resistance of hepatitis B virus (HBV) originates from mutations within HBV reverse transcriptase (RT) region during the prolonged antiviral therapy. So far, the characteristics of how these mutations distribute and evolve in the process of therapy have not been clarified yet. Thus we aimed to investigate these characteristics and discuss their contributing factors.

Methods: HBV RT region was direct-sequenced in 285 treatment-naive and 214 post-treatment patients. Mutational frequency and Shannon entropy were calculated to identify the specific mutations differing between genotypes or treatment status. A typical putative resistance mutation rtL229V was further studied using in-vitro susceptibility assays and molecular modeling.

Results: The classical resistance mutations were rarely detected among treatment-naive individuals, while the putative resistance mutations were observed at 8 AA sites. rtV191I and rtA181T/V were the only resistance mutations identified as genotype-specific mutation. Selective pressure of drug usage not only contributed to the classical resistance mutations, but also induced the changes at a putative resistance mutation site rt229. rtL229V was the major substitution at the site of rt229. It contributed to the most potent suppression of viral replication and reduced the in-vitro drug susceptibility to entecavir (ETV) when coexisting with rtM204V, consistent with the hypothesis based on the molecular modeling and clinical data analysis.

Conclusions: The analysis of mutations in RT region under the different circumstances of genotypes and therapy status might pave the way for a better understanding of resistance evolution, thus providing the basis for a rational administration of antiviral therapy.

Combined viral quasispecies diversity and hepatitis B core-related antigen predict off-nucleos(t)ide analog durability in HBeAg-negative patients

BACKGROUND

Viral quasispecies dynamics between pre- and post-nucleos(t)ide analog (NA) therapy remains unclear.

AIM

This study aimed to investigate the HBV quasispecies evolution and its relationship with durability of off-therapy responses in HBeAg-negative chronic hepatitis B (CHB) patients who stopped NA therapy.

METHODS

Fifty-four HBeAg-negative CHB patients who stopped NAs, including 19 virological controllers (VC) who maintained serum HBV DNA < 2000 IU/mL beyond 1-year off-therapy, and 35 virological relapsers (VR) experiencing virological relapse within 1-year off-therapy were recruited. Viral quasispecies was analyzed by deep sequencing. Hepatitis B core-related antigen (HBcrAg) and HBsAg were also measured.

RESULTS

VC had significantly higher baseline viral quasispecies diversity of the precore/core gene, measured by nucleotide diversity, than VR. Low baseline viral nucleotide diversity (< 0.01) and high HBcrAg (≧ 2.0 KU/mL), but not HBsAg, at end of treatment (EOT) were significantly associated with higher risk of 1-year virological relapse (hazard ratio [HR] 6.09 and 3.31, respectively). Combination of low baseline viral nucleotide diversity and high HBcrAg at EOT could identify patients at high risk (HR 15.82). Further analysis of the evolution of HBV whole genome showed that HBV nucleotide diversity negatively correlated with serum HBV DNA levels. Notably, the viral quasispecies diversity between pre- and post-NA treatment remained relatively unchanged.

CONCLUSION

Higher baseline HBV quasispecies diversity associates with more durable off-therapy viral suppression in HBeAg-negative CHB patients. Combination of baseline viral nucleotide diversity and HBcrAg at EOT can identify patients at high risk for virological relapse after stopping NAs.

Hepatitis b infection: progress in identifying patients most likely to respond to peginterferon alfa

Introduction: Despite the disadvantage of side effects, pegylated interferon alpha (Peg-IFN α) remains an indispensable agent for chronic hepatitis B (CHB) due to its immunomodulatory effect. The selection of a patient most likely to have a favorable response becomes an essential issue for Peg-IFN α therapy.Areas covered: Recent progress in the prediction of the treatment response to Peg-IFN α.Expert opinion: Before Peg-IFN α therapy, baseline host and viral factors, including female sex, younger age, a high alanine aminotransferase level, HBV genotype A or B, and low viral load, predict a favorable response. In addition, on-treatment viral kinetics of hepatitis B surface antigen (HBsAg), e antigen (HBeAg) and HBV DNA help clinicians determine whether to continue or discontinue Peg-IFN α therapy. The novel HBV markers hepatitis B core-related antigen and HBV RNA have recently been investigated as useful predictors. The limited efficacy of Peg-IFN α monotherapy facilitated the development of new strategies of 'add-on' or 'switch to' Peg-IFN α in patients receiving long-term nucleot(s)ide analog treatment, which may lead to an increase in HBeAg and HBsAg loss. In summary, tailored Peg-IFN α therapeutic strategies based on predictors extended the landscape for CHB treatment.

Next-generation sequencing for the diagnosis of hepatitis B: current status and future prospects

INTRODUCTION

Hepatitis B virus (HBV) causes a complex and persistent infection with a major impact on patients health. Viral-genome sequencing can provide valuable information for characterizing virus genotype, infection dynamics and drug and vaccine resistance.

AREAS COVERED

This article reviews the current literature to describe the next-generation sequencing progress that facilitated a more comprehensive study of HBV quasispecies in diagnosis and clinical monitoring.

EXPERT OPINION

HBV variability plays a key role in liver disease progression and treatment efficacy. Second-generation sequencing improved the sensitivity for detecting and quantifying mutations, mixed genotypes and viral recombination. Third-generation sequencing enables the analysis of the entire HBV genome, although the high error rate limits its use in clinical practice.