Hepatitis B Virus Genotype B and High Expression of Interferon Alpha Receptor β Subunit are Associated With Better Response to Pegylated Interferon Alpha 2a in Chinese Patients With Chronic Hepatitis B Infection

Hepatitis B virus genotypes influence clinical outcomes: A review

Hepatitis B virus (HBV) is a hepatotropic virus that affects approximately 296 million people worldwide. A crucial step to HBV replication is the transcription of its infectious DNA from its viral RNA intermediate. The production of the RNA intermediate hinges on reverse transcription, and therefore the lack of proofreading in that process commonly yields mutants and has led to nine well-described genotypes (A-I) and over 30 known sub-genotypes of the virus. The influence of genotype on HBV infection outcomes, which include fibrosis progression, cirrhosis, and hepatocellular carcinoma (HCC), remain uncertain. This review aims to analyze the influence of HBV genotype on the risk of development of these outcomes. The response to current and future HBV therapies is considered. Further study of larger and more diverse samples will hopefully resolve outstanding uncertainties.

The response of hepatitis B virus genotype to interferon is associated with a mutation in the interferon-stimulated response element

Genetic variation and genotype of Hepatitis B virus (HBV) are related to the efficiency of interferon alpha (IFN-α)-based antiviral therapy. However, the correlation of variation in interferon-stimulated response element (ISRE) and HBV genotype response to IFN-α therapy remains elusive.Differences of ISRE between genotype B and C HBV were explored using the HBV sequences retrieved from GenBank, and further investigated by ISRE region cloning and sequencing from 60 clinical samples post-IFN-α therapy. Additionally, ISRE mutants were constructed and their relation to responsiveness of IFN-α was evaluated by real-time PCR and Southern blot analysis.ISRE pattern between genotype B and C were found based on both clinical sample sequencing and full-length sequence alignment. The primary difference is the fourth base within the ISRE region, with T and C for genotype B and C, respectively. HBV with genotype C-type ISRE had a higher replicative capability as compared to HBV with genotype B-type ISRE after IFN-α treatment in huh7 cells. CONCLUSION:: Preference of ISRE between genotype B and C HBV are distinct. Single nucleotide difference (C to T) within the HBV ISRE region may link to the efficacy of IFN-α therapy to genotype B and C HBV. Therefore, this study provides a clue for the determination of IFN-α therapy response to HBV treatment.

Polymorphisms of CYP27B1 are associated with IFN efficacy in HBeAg-positive patients

BACKGROUND

Host single nucleotide polymorphisms were associated with antiviral therapy in CHB patients. The CYP27B1 gene, encoding 25(OH)D₃ -1α hydroxylase, might activate 25(OH)D₃ to 1,25(OH)₂ D₃ in kidney resulted in influencing the efficacy of interferon (IFN). The aim of the study was to investigate the association between CYP27B1 polymorphisms and the response to IFN in HBeAg-positive patients.

METHODS

Eighty-seven HBeAg-positive CHB patients infected with HBV genotype B or C were included in the study. All patients were treated with IFN at least 1 year. According to the response to PEG-IFN therapy, they were divided into three groups: 16 complete responses (CR), 42 partial responses (PR), and 29 nonresponses (NR). Sanger-sequencing was utilized to genotype the CYP27B1 SNPs(rs4646536 and rs10877012).

RESULTS

In logistic regression analysis, the frequency of rs4646536 CC genotype was observed to be higher in the NR group. Besides, the GG genotype of rs10877012 differed significantly among the three groups. The GG genotype was prevalent in patients with CR, and patients with TT genotype result in NR at the end of IFN treatment. The most common haplotype TG was independently associated with CR, after adjustment, and haplotype CT appeared to be associated with NR and PR, rather than CR. The data also showed that patients with baseline 1,25(OH)₂ D₃ > 39.39 pg/mL had higher CR rates at the end of IFN therapy.

CONCLUSION

These results suggested CYP28B1 gene polymorphisms may be independently associated with the efficacy of IFN in HBeAg-positive patients.

Characterization of Occult Hepatitis B Infection Among Injecting Drug Users in Tehran, Iran

BACKGROUND

Hepatitis B virus (HBV) infection is a major health problem worldwide.

OBJECTIVES

The aim of this study was to investigate the frequency of occult hepatitis B infection (OBI) and its associated risk factors, together with the molecular characterization of the virus in injecting drug users of Tehran.

PATIENTS AND METHODS

The study consisted of 229 injecting drug users. Serum samples were collected and tested for the presence of hepatitis B core antibody (HBcAb) and hepatitis B surface antigen (HBsAg) by an enzyme-linked immunosorbent assay (ELISA). HBV B virus DNA was extracted from the serum samples, and a fragment of the S gene was amplified using the nested polymerase chain reaction. The genotype, subgenotypes, subtype, and S gene mutation of HBV were determined by direct sequencing. A phylogenetic tree was constructed using the neighbor-joining method.

RESULTS

Sixty-four (28%) participants were HBcAb positive, 59 cases were HBcAb positive and HBsAg negative, and 5 cases were HBsAg positive. Hepatitis B DNA was found in three HBsAg-positive cases. Thirteen of 59 (22%) individuals were hepatitis B DNA positive. The phylogenetic tree of hepatitis B DNA showed the existence of genotype D. The only significant correlation was between sharing a syringe and OBI.

CONCLUSIONS

In comparison with the rate of HBcAb positivity reported in other Iranian studies, the rate was higher in the present study. There were a few variations, genotypes, and subtypes among the infected injecting drug users. Further investigations are needed to unravel the molecular characterization of OBI.

Relationship between hepatitis B virus genotype B and C and response to interferon therapy in HBeAg positive chronic hepatitis B patients: A meta-analysis

BACKGROUND AND AIMS

Previous studies examining the relationship between hepatitis B virus (HBV) genotype B and C and response to interferon therapy in Hepatitis B e antigen (HBeAg)-positive chronic hepatitis B patients have yielded conflicting results. We aim to summarize data to reach firm conclusions on the role of HBV genotype B and C in response to interferon therapy.

METHODS

PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched for relevant articles published up to March 2013. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated by fixed- or random-effects models. Heterogeneity, sensitivity analysis, and publication bias were also assessed.

RESULTS

Fifteen studies were identified. All studies except for those evaluating the rate of end-of-treatment HBeAg seroconversion exhibited significant heterogeneity. There were significant differences in rates of end-of-treatment alanine aminotransferase (ALT) normalization, HBV DNA negative, and HBeAg seroconversion between the genotype B and genotype C groups, but not in HBeAg clearance. The pooled results showed higher rates of sustained ALT normalization (OR = 2.24, 95%CI 1.53-3.27), HBV DNA negative (OR = 2.60, 95%CI 1.65-4.12), HBeAg clearance (OR = 2.13, 95%CI 1.29-3.52) and HBeAg seroconversion (OR = 1.95, 95%CI 1.27-2.98) in patients with genotype B than those with genotype C. The sensitivity analysis did not alter the effects observed in the primary analysis. There was no evidence of publication bias except for HBeAg clearance rate.

CONCLUSIONS

The results of the current meta-analysis indicate that HBV genotype B patients receiving interferon therapy respond better to treatment compared with genotype C patients, but this needs to be further examined.

Hepatitis B virus genetic mutations and evolution in liver diseases

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus of the Hepadnaviridae family and is approximately 3.2 kb in length. Owing to a lack of proofreading capacity during reverse transcription and a high replication rate, HBV exhibits as quasispecies. To detect the genetic mutations of HBV, many methods with different sensitivities and throughputs were developed. According to documentary records, HBV mutation and evolution were important vial parameters in predicting disease progression and therapeutic outcome. In this review, we separately discussed the correlation between HBV genomic mutations in four open reading frames and liver disease progression. Since some of the results were controversial from different laboratories, it remains to be seen whether functional analyses will confirm their role in modifying the course of infection.

Hepatitis B virus genotypes: Global distribution and clinical importance

At least 600000 individuals worldwide annually die of hepatitis B virus (HBV)-related diseases, such as chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). Many viral factors, such as viral load, genotype, and specific viral mutations, are known to affect disease progression. HBV reverse transcriptase does not have a proofreading function, therefore, many HBV genotypes, sub-genotypes, mutants, and recombinants emerge. Differences between genotypes in response to antiviral treatment have been determined. To date, 10 HBV genotypes, scattered across different geographical regions, have been identified. For example, genotype A has a tendency for chronicity, whereas viral mutations are frequently encountered in genotype C. Both chronicity and mutation frequency are common in genotype D. LC and progression to HCC are more commonly encountered with genotypes C and D than the other genotypes. Pathogenic differences between HBV genotypes explain disease intensity, progression to LC, and HCC. In conclusion, genotype determination in CHB infection is important in estimating disease progression and planning optimal antiviral treatment.