A complete genomic analysis of hepatitis B virus genotypes and mutations in HBeAg-negative chronic hepatitis B in China

A Recent Prevalence of Hepatitis B Virus (HBV) Genotypes and Subtypes in Asia: A Systematic Review and Meta-Analysis

Background and Aim: Despite introducing the hepatitis B virus (HBV) vaccine, the incidence of the Hepatitis B virus globally is still a major health concern. This systematic review and meta-analysis were conducted to provide detailed information on the prevalence of HBV genotypes and subtypes in circulation in Asia. Methods: A systematic search for articles describing the prevalence of HBV genotypes and subtypes in Asia was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Results: Our search returned 207 eligible articles involving 49,279 genotypes and 7457 subtypes representing 28 Asian countries. A meta-analysis was performed on our eligible studies using the Random effect Model. The pooled prevalence of HBV genotypes showed that genotype C (30.9%) (95% CI, 27.5–34.5%; I2 = 97.57%; p < 0.001) was the most common HBV genotype in Asia, followed by genotype B (17.8%) (95% CI, 15.5–20.4%; I2 = 97.26%; p < 0.001) and genotype D (15.4%) (95% CI, 11.8–19.8%). Vietnam had the highest prevalence of genotype B, Lebanon had the highest prevalence of genotypes C, and Jordan had the highest prevalence of genotype D. There was variation in genotypic prevalence with respect to the target genes for HBV genotyping. Reverse dot blot hybridization had the highest estimate of genotypes B and C. HBV subtype C2 (40.0%) (95% CI, 33.3–47.0) is the most prevalent HBV subtype. Conclusion: Evidence from this study reveals that HBV genotypes C and B are the most dominant HBV genotypes in Asia, and HBV subtype C2 is more endemic in Asia.

Interpretation of HBV Serologies

Hepatitis B was discovered by researchers who were investigating jaundice associated with blood transfusions as well as parenterally administered medications. Through trial and error, the HBV was identified. There are specific tests that detect HBV infection, whether it is a previous exposure or active infection. The various HBV serologies are reviewed in this work as well. Hepatitis B surface antigen has emerged as a tool in defining treatment endpoint and its significance is reviewed. HBV genotypes are distributed uniquely throughout the world, in particular, genotype C is associated with higher rates of hepatocellular carcinoma. Various HBV genotypes and their impact on the clinical course are discussed. The relationship of HBV serologies and HBV DNA to disease progression is outlined. There are specific recommendations on monitoring those infected with HBV and this is reviewed here. HBV mutations have an impact on the disease course and those of significance are also discussed.

Genotypes and viral variants in chronic hepatitis B: A review of epidemiology and clinical relevance

The Hepatitis B Virus (HBV) has a worldwide distribution and is endemic in many populations. It is constantly evolving and 10 genotypic strains have been identified with varying prevalences in different geographic regions. Numerous stable mutations in the core gene and in the surface gene of the HBV have also been identified in untreated HBV populations. The genotypes and viral variants have been associated with certain clinical features of HBV related liver disease and Hepatocellular carcinoma. For example Genotype C is associated with later hepatitis B e antigen (HBeAg) seroconversion, and more advanced liver disease. Genotype A is associated with a greater risk of progression to chronicity in adult acquired HBV infections. Genotype D is particularly associated with the precore mutation and HBeAg negative chronic hepatitis B (CHB). The genotypes prevalent in parts of West Africa, Central and South America, E, F and H respectively, are less well studied. Viral variants especially the Basal Core Promotor mutation is associated with increased risk of fibrosis and cancer of the liver. Although not currently part of routine clinical care, evaluation of genotype and viral variants may provide useful adjunctive information in predicting risk about liver related morbidity in patients with CHB.

A complete genomic analysis of hepatitis B virus isolated from 516 Chinese patients with different clinical manifestations

This study investigated features and clinical implications of HBV mutations in patients with different clinical manifestations. In total, 516 patients were enrolled in this study, including 131 patients with acute hepatitis B, 239 patients with chronic hepatitis B, and 146 patients with acute-on-chronic liver failure. HBV genotypes and mutations were analyzed by direct sequencing of complete viral genomes. Genotypes B2, C1, C2, and D1 accounted for 22.2%, 1.6%, 74.6%, and 1.6%, respectively. Genotype B was more frequently detected in patients with acute hepatitis B than those with chronic hepatitis B and acute-on-chronic liver failure. Deletion mutations were detected mostly in preS1 and preS2 regions and the detection rates were 3.8%, 19.7%, and 24.7% for acute hepatitis B, chronic hepatitis B and acute-on-chronic liver failure patients, respectively. Incidences of point mutation T53C (preS1F53L), G1613A (polR841K), G1775A and A1762T + G1764A in the basal core promoter region, G1896A and G1899A in precore region and A2189C (coreI97L) in core region increased along with acute hepatitis B, chronic hepatitis B, and acute-on-chronic liver failure. The mutation G1896A was independently associated with poor survival of patients with acute-on-chronic liver failure. The gradual increase of viral mutation incidences was also observed in three HLA-A2-restricted cytotoxic T lymphocyte epitopes from HLA-A2-positive patients, that is env188-196 (5.8%, 10.1%, 22.5%), core107-115 (4.3%, 4.6%, 19.7%), and x92-100 (1.4%, 20.2%, 33.8%). In conclusion, certain viral mutations in various regions of HBV genome are associated with disease progression of HBV infection.

HBV genotypes: relevance to natural history, pathogenesis and treatment of chronic hepatitis B

Although chronic HBV infection is the leading cause of chronic liver disease and death worldwide, there are substantial differences in its clinical courses regarding prevalence, mode of transmission, characteristics of each phase, responses to antiviral therapy, and development of cirrhosis and hepatocellular carcinoma, according to geographical areas (Asia versus Western Europe and North America versus Africa). Furthermore, the clinical course in infected individuals depends on a complex interplay among various factors including viral, host, environmental and other factors. Recently, understanding of molecular characteristics of the prevailing HBV genotypes, frequently accompanied mutations and their clinical implications might explain these geographical differences more pertinently. Hence, in this article, we review the global epidemiology and the natural history of HBV infection, with emphasis on summarizing the different HBV genotypes according to regions.

Virologic and clinical characteristics of HBV genotypes/subgenotypes in 487 Chinese pediatric patients with CHB

Background

The association of hepatitis B virus (HBV) genotypes/subgenotypes with clinical characteristics is increasingly recognized. However, the virologic and clinical features of HBV genotypes/subgenotypes in pediatric patients remain largely unknown.

Methods

Four hundred and eighty-seven pediatric inpatients with CHB were investigated, including 217 nucleos(t)ide analog-experienced patients. HBV genotypes/subgenotypes and reverse transcriptase (RT) mutations were determined by direct sequencing. The stage of fibrosis and degree of inflammatory activity were evaluated by the Metavir score system.

Results

Among 487 enrolled pediatric patients, HBV genotype C2 and B2 were the most two prevalent (73.7% and 21.1%). Comparing with HBV/B2 infected patients, no significant difference was observed in the incidence rate and mutant patterns of lamivudine- or adefovir-resistant mutations in HBV/C2 infected patients (P > 0.05). Importantly, we found that the degree of hepatic inflammation degree, fibrosis stage and ALT level were significantly higher in HBV/C2-infected HBeAg positive patients than it was in HBV/B2-infected ones.

Conclusions

The pediatric patients with HBV/C2 infection might be more susceptible to develop severe liver pathogenesis.

Hepatitis B virus (HBV) subgenotypes C2 and B2 differ in lamivudine- and adefovir-resistance-associated mutational patterns in HBV-infected Chinese patients

We aimed to study the prevalence and clinical implications of hepatitis B virus (HBV) subgenotypes in Chinese patients. A total of 4,300 patients, mainly from northern China, were enrolled, including 182 patients with acute hepatitis B and 4,118 patients with chronic HBV infection who had been exposed to nucleoside or nucleotide analogs. HBV genotypes/subgenotypes were determined by direct sequencing of the HBV S/Pol region. The prevalence rates were 0.40% for HBV/B1, 14.30% for HBV/B2, 0.25% for HBV/B3, 0.35% for HBV/B4, 1.05% for HBV/C1, 81.72% for HBV/C2, 0.93% for HBV/C3, 0.16% for HBV/C4, and 0.84% for HBV/D. In chronic HBV infection, patients with HBV/B2 were younger and had lower ΗBeAg positive rates than patients with HBV/C2. The incidence of lamivudine-resistant mutations was significantly higher in HBV/C2 compared to HBV/B2 (27.9% versus 19.8%; P<0.01), and the significant difference was observed only for rtM204I and not rtM204V. In addition, compensatory mutations were more frequently detected in HBV/C2. The incidence of adefovir-resistant mutations was similar between the two subsets, but HBV/C2 inclined to show rtA181V (3.6% for C2 versus 0.9% for B2; P<0.01), while HBV/B2 inclined to show rtN236T (4.5% for versus 2.5% for C2; P<0.01). The ratios of HBV/B2 to HBV/C2 infection were 1.7 (110/65), 5.7 (2,653/463), 7.5 (520/69), 8.0 (48/6), and 15.3 (183/12) for acute hepatitis B, chronic hepatitis B, liver cirrhosis, acute-on-chronic liver failure, and hepatocellular carcinoma, respectively. In conclusion, HBV/C2 and HBV/B2, two prevalent subgenotypes, differ in lamivudine- and adefovir-resistance-associated mutational patterns. HBV/C2-infected patients are more likely to have disease progression than HBV/B2-infected ones.

HBV genotype C is independently associated with cirrhosis in community-based population

AIM: To determine the association of hepatitis B virus (HBV) genotypes with probable cirrhosis and fatty liver in community-based populations.

METHODS: A multi-stage cluster probability sampling method was applied to recruit 10 167 subjects aged between 6 and 72 years from our epidemiological bases in Eastern China. After excluding the subjects co-infected with hepatitis C or hepatitis D viruses, the hepatitis B surface antigen (HBsAg)-positive subjects were examined for HBV genotype, serum viral load, alanine aminotransferase (ALT), hepatitis B e antigen (HBeAg) status, and ultrasonographic changes. Logistic regression models were used to determine the factors associated with probable cirrhosis and fatty liver.

RESULTS: Of 634 HBsAg-positive subjects with HBV genotype determined, 82 had probable cirrhosis (ultrasonographic score ≥ 5), 42 had ultrasonographic fatty liver. Probable cirrhosis was only found in the HBeAg-negative subjects, and more frequently found in the subjects with genotype C than in those with genotype B (14.8% vs 8.0%, P = 0.018). In HBeAg-negative subjects, high viral load was frequently associated with abnormal ALT level, while ALT abnormality was more frequent in those with probable cirrhosis than those without (19.5% vs 7.8%, P = 0.001). Univariate analysis showed that age, sex, HBV genotypes, and viral load were not significantly associated with ultrasonographic fatty liver, whereas ALT abnormality was significantly related to ultrasonographic fatty liver (OR = 4.54, 95% CI: 2.11-9.75, P < 0.001). Multivariate analysis demonstrated that HBV genotype C, age (≥ 45 years), male sex, and ALT abnormality were independently associated with probable cirrhosis (AOR = 2.30, 95% CI: 1.26-4.19; AOR = 1.81, 95% CI: 1.10-2.99; AOR = 1.74, 95% CI: 1.03-2.95; AOR = 2.98, 95% CI: 1.48-5.99, respectively).

CONCLUSION: A crude prevalence of probable cirrhosis is 12.9% in the community-based HBV-infected subjects. HBV genotype C is independently associated with probable cirrhosis in the HBeAg-negative subjects.

Geographical and genetic diversity of the human hepatitis B virus

Hepatitis B virus (HBV) is one of the most widely distributed viruses that infect humankind. Distinct clinical and virological characteristics of the HBV-infection have been reported in different geographical parts of the world and are increasingly associated with genetic diversity of the infecting virus. HBV is classified into genotypes and subgenotypes that are associated with ethnicity and geography. The genetic diversity of HBV in its various aspects has been the subject of extensive investigations during the last few decades. Since molecular epidemiology research tools have become widely available, the number of new publications in this field has grown exponentially. This review summarises the recent publications on the geographical distribution of genetic variants of HBV, and proposes updated criteria for the identification of new genotypes and subgenotypes of the virus.

Hepatitis B virus genotype C is associated with more severe liver fibrosis than genotype B

BACKGROUND & AIMS

Histologic analyses of liver fibrosis have been limited by small sample sizes and the predominance of samples from patients with active hepatitis.

METHODS

We performed a prospective study of transient elastography in treatment-naive patients with chronic hepatitis B, to investigate the relationship between hepatitis B virus (HBV) genotype and liver fibrosis. A validated liver stiffness measurement algorithm was used to define insignificant fibrosis and advanced fibrosis.

RESULTS

Of 1106 patients, 711 (64%) were older than age 40, 370 (34%) had positive test results for hepatitis B e antigen (HBeAg), and 386 (35%) had increased serum levels of alanine aminotransferase. Of the patients, 524 (49%) had genotype B and 582 (51%) had genotype C HBV infection. Patients with genotype C infection had insignificant fibrosis less often (42% vs 55%; P < .0001) and advanced fibrosis more often (25% vs 19%; P = .015) than those infected with genotype B HBV. The difference in the severity of liver fibrosis between the 2 HBV genotypes was most marked among patients older than age 40 and those who tested negative for HBeAg. The mean age of patients infected by genotype C was greater than that of patients infected by genotype B HBV (41 vs 36 y). Among patients who were older than age 40 and tested negative for HBeAg, those with genotype C infection had higher levels of HBV DNA and alanine aminotransferase than those with genotype B HBV.

CONCLUSIONS

Genotype C HBV was associated with more severe liver fibrosis than genotype B HBV, probably because of delayed HBeAg seroconversion and prolonged active disease.

Novel hepatitis B virus subgenotype A6 in African-Belgian patients

BACKGROUND

Genome diversity of hepatitis B virus (HBV) is prominent among DNA viruses; which, allowed the virus to be genetically classified into eight genotypes and several subgenotypes.

OBJECTIVE

To introduce and to characterize a novel subgenotype HBV, classified as A6.

STUDY DESIGN

HBV full-length genomes were isolated and sequenced from three African-Belgian patients chronically infected with the virus. Using phylogenetic reconstruction and genetic distance calculation, the evolutionary relationships of the novel strains were investigated.

RESULTS

Phylogenetic analysis based on complete genome sequences of genotype A strains revealed distinct clusters supported by high bootstrap values. The three African-Belgian strains clustered separately from the other known A subgenotypes (A1-A5) with maximal bootstrap support (100%). The mean inter-subgenotypic nucleotide divergence over the complete genome sequence between the novel A6 strains and A1-A5 was higher than 4%.

CONCLUSION

Phylogenetic analysis of the complete genome sequences yielded maximal bootstrap value support for nodes that establish the new lineage as a novel subgenotype. In addition, nucleotide divergence more than 4% based on full-length genome of the virus, clearly demonstrated that the three African-Belgian strains belonged to a novel subgenotype of HBV, which was assigned as "A6". Noteworthy, the phylogeny of genotype A demonstrated that the A6 is a basal lineage that diverged earlier from the other African subgenotypes of genotype A.

Application of metabonomic analytical techniques in the modernization and toxicology research of traditional Chinese medicine

In the recent years, a wide range of metabonomic analytical techniques are widely used in the modern research of traditional Chinese medicine (TCM). At the same time, the international community has attached increasing importance to TCM toxicity problems. Thus, many studies have been implemented to investigate the toxicity mechanisms of TCM. Among these studies, many metabonomic-based methods have been implemented to facilitate TCM toxicity investigation. At present, the most prevailing methods for TCM toxicity research are mainly single analysis techniques using only one analytical means. These techniques include nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS), etc.; with these techniques, some favourable outcomes have been gained in the toxic reaction studies of TCM, such as the action target organs assay, the establishment of action pattern, the elucidation of action mechanism and the exploration of action material foundation. However, every analytical technique has its advantages and drawbacks, no existing analytical technique can be versatile. Multi-analysed techniques can partially overcome the shortcomings of single-analysed techniques. Combination of GC-MS and LC-MS metabolic profiling approaches has unravelled the pathological outcomes of aristolochic acid-induced nephrotoxicity, which can not be achieved by single-analysed techniques. It is believed that with the further development of metabonomic analytical techniques, especially multi-analysed techniques, metabonomics will greatly promote TCM toxicity research and be beneficial to the modernization of TCM in terms of extending the application of modern means in the TCM safety assessment, assisting the formulation of TCM safety norms and establishing the international standards indicators.