The influence of hepatitis B virus genotype and subgenotype on the natural history of chronic hepatitis B

Is there any value to hepatitis B virus genotype analysis?

Hepatitis B may cause a varying spectrum of diseases ranging from an asymptomatic or mild anicteric acute illness, to severe or fulminant hepatitis. Similarly, the outcome of chronic hepatitis B is variable. Viral factors associated with outcome of chronic hepatitis B virus (HBV) infection include hepatitis B e antigen status, HBV DNA, genotype, and HBV variants. HBV genotypes and subgenotypes have been associated with differences in clinical and virological characteristics, indicating that they may play a role in the virus-host relationship. A total of ten hepatitis B virus genotypes have been defined with a distinct geographical distribution. Hitherto, genotypes A, B, C and D have been studied most extensively. The HBV genotype appears to influence not only the natural history of HBV related liver disease but also the response to HBV treatment. HBV genotypes are also linked with both core promoter and BCP mutations. Progression to chronic infection appears to occur more frequently following acute infection with genotypes A and D than with the other studied genotypes. Genotypes A and B appear to have higher rates of spontaneous HBeAg seroconversion. More advanced liver disease and progression to HCC is more often seen in chronic infection with genotypes C and D in contrast to genotypes A and B. More specifically, genotypes A1, C, B2-B5 and H appear to be associated with more serious complications than genotypes A2, B1 and B6. These observations suggest important pathogenic differences between HBV genotypes. Genotypes A and B have higher response rates to interferon based therapy than genotypes C and D. Knowledge of HBV genotype enables clinicians to identify those patients at increased risk of disease progression whilst aiding the selection of appropriate antiviral therapy. Genotyping and monoclonal subtyping can provide useful information for epidemiological studies. In conclusion, genotyping of chronic HBV infections can help practicing physicians identify those at risk of disease progression and determine optimal anti-viral therapy.

The characteristics of the synonymous codon usage in hepatitis B virus and the effects of host on the virus in codon usage pattern

BACKGROUND

Hepatitis B virus (HBV) infection is one of the main human health problem and causes a large-scale of patients chronic infection worldwide.. As the replication of HBV depends on its host cell system, codon usage pattern for the viral gene might be susceptible to two main selections, namely mutation pressure and translation selection. In this case, a deeper investigation between HBV evolution and host adaptive response might assist control this disease.

RESULT

Relative synonymous codon usage (RSCU) values for the whole HBV coding sequence were studied by Principal component analysis (PCA). The characteristics of the synonymous codon usage patterns, nucleotide contents and the comparison between ENC values of the whole HBV coding sequence indicated that the interaction between virus mutation pressure and host translation selection exists in the processes of HBV evolution. The synonymous codon usage pattern of HBV is a mixture of coincidence and antagonism to that of host cell. But the difference of genetic characteristic of HBV failed to be observed to its different epidemic areas or subtypes, suggesting that geographic factor is limited to influence the evolution of this virus, while genetic characteristic based on HBV genotypes could be divided into three groups, namely (i) genotyps A and E, (ii) genotype B, (iii) genotypes C, D and G.

CONCLUSION

Codon usage patterns from PCA for identification of evolutionary trends in HBV provide an alternative approach to understand the evolution of HBV. Further more, a combined selection of mutation pressure with translation selection on codon usage might shed a light on understanding the evolutionary trends of HBV genotypes.

Role of hepatitis B virus genetic barrier in drug-resistance and immune-escape development

BACKGROUND

Impact of hepatitis B virus genetic barrier, defined as the number and type of nucleotide substitutions required to overcome drug/immune selective pressure, on drug-resistance/immune-escape development is unknown.

METHODS

Genetic barrier was calculated according to Van de Vijver (2006) in 3482 hepatitis B virus-reverse transcriptase/HBV surface antigen sequences from 555 drug-naïve patients and 2927 antiviral-treated patients infected with hepatitis B virus genotypes A-G.

RESULTS

Despite high natural variability, genetic barrier for drug-resistance development is identical amongst hepatitis B virus genotypes, but varies according to drug-resistance mutation type. Highest genetic barrier is found for secondary/compensatory mutations (e.g. rtL80I/V-rtL180M-rtV173L), whilst most primary mutations (including rtM204V-rtA181T/V-rtI169T-rtA194T) are associated with low genetic barrier. An exception is rtM204I, which can derive from a transition or a transversion. Genotypes A and G are more prone to develop immune/diagnostic-escape mutations sT114R and sG130N. Vaccine-escape associated sT131N-mutation is a natural polymorphism in both A and G genotypes.

CONCLUSION

Genetic barrier and reverse transcriptase/HBV surface antigen overlapping can synergistically influence hepatitis B virus drug-resistance/immune-escape development. The different immune-escape potential of specific hepatitis B virus genotypes could have important clinical consequences in terms of disease progression, vaccine strategies and correct HBV surface antigen detection.

Hepatocellular carcinoma and other liver disease among Greenlanders chronically infected with hepatitis B virus: a population-based study

BACKGROUND

In Greenland, the prevalence of hepatitis B surface antigen carriers, reflecting chronic hepatitis B virus (HBV) infection, is 5%-10%. However, the incidence of cirrhosis and hepatocellular carcinoma in this population has been reported to be low. We investigated this discrepancy in a large population-based cohort study.

METHODS

In total, 8879 Greenlanders (16% of the population) were recruited for population-based surveys performed from May 5 to July 7, 1987, and from November 1 to November 21, 1998, with follow-up until March 31, 2010. HBV status was based on serological testing, supplemented by data from all available HBV registries in Greenland to determine changes in HBV status over time. Information on morbidity and mortality was obtained from the Patient Discharge Registry, the Cancer Registry, and the Central Registration System. Sex, age, ethnicity, and period-adjusted incidence rate ratios (IRRs) were estimated using Poisson regression. World standardized rates were derived from these and World Health Organization data.

RESULTS

The 650 chronically HBV-infected persons had higher rates of hepatocellular carcinoma (adjusted IRR = 8.70; 95% CI = 2.06 to 36.7), liver disease (adjusted IRR = 5.73, 95% CI = 3.52 to 9.34), and all-cause mortality (adjusted IRR = 1.47; 95% CI = 1.21 to 1.79) than the 5160 HBV-negative persons. However, the world standardized incidence rates of hepatocellular carcinoma (38.5 cancers per 100 000 person-years) and cirrhosis (24 cases per 100 000 person-years) among chronically HBV-infected persons were low compared with results from population-based studies from countries with low, intermediate, and high rates of endemic HBV infection.

CONCLUSION

The relatively low incidence of hepatocellular carcinoma and other HBV-related morbidity among chronic HBV-infected persons in Greenland suggest a more benign course of HBV among the Greenlandic Inuit than in populations in other parts of the world.

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.

Characterization of drug-resistance mutations in HBV D-genotype chronically infected patients, naïve to antiviral drugs

Presence of drug-resistance mutations in drug-naïve hepatitis B virus (HBV) infected patients can seriously compromise response to antiviral treatment. Therefore, our study was aimed at defining the prevalence of HBV drug-resistance in a population of 140 patients, all infected with HBV-D-genotype (the most common HBV-genotype in Eastern Europe, Mediterranean countries and Middle East) and naïve to antiviral therapy. HBV reverse-transcriptase (RT) region was sequenced and analyzed for 20 mutations, confirmed by in vitro studies as associated with resistance to nucleos(t)ide HBV-RT inhibitors (rtL80I/V-rtI169T-rtV173L-rtL180M-rtA181T/V/S-rtT184A/S/G/C-rtA194T-rtS202C/G/I-rtM204V/I-rtN236T-rtM250V). Amino acid changes at other six RT positions, potentially associated with resistance, were also analyzed (rtV84M-rtV191I-rtV207L-rtV214A-rtQ215S-rtI233V). Overall, only 2/140 (1.4%) patients carried primary drug-resistance mutations [rtA181V (0.7%), and rtA194T (0.7%)], while 3/140 (2.1%) patients harbored the secondary mutations rtV173L (1.4%) and rtL180M (0.7%). Additionally, five polymorphic mutations, with a suggested role in drug resistance, were detected [rtQ215S (12.8%), rtI233V (4.3%), rtV214A (3.6%), rtV191I (0.7%), rtV207L (0.7%)]. Notably, no YMDD mutations, namely rtM204V/I, were found. Taken together, the rate of important drug resistance mutations in naïve HBV D-genotype infected patients is today very low, and suggests the potential full efficacy of new-generation antiviral drugs used in first line therapy. Whether such low rate can be extrapolated to non HBV-D subtypes, requires a detailed investigation to be performed in a different cohort of patients.

Molecular epidemiology of hepatitis B virus

Although safe and effective vaccines for hepatitis B virus (HBV) have been available for nearly three decades, this virus kills at least 600,000 people annually worldwide and remains the leading global cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Because the HBV reverse transcriptase lacks a proofreading function, many HBV genotypes, subgenotypes, mutants, and recombinants exist. At least 10 HBV genotypes (HBV-A through J) with distinct geographic distributions have been identified; by definition, their complete genomic sequences diverge by more than 8%. HBV genotype is increasingly becoming recognized as an important factor in the progression and clinical outcome of HBV-induced disease. Infections by HBV-C or -D are significantly more likely to lead to cirrhosis and hepatocellular carcinoma than are infections by HBV-A or -B. Additionally, the hepatitis B e antigen seroconversion response to standard or pegylated interferon is more favorable in patients with HBV-A or -B than in those with HBV-C or -D. However, therapeutic responses to nucleos(t)ide analogues are generally comparable among HBV genotypes. In conclusion, genotyping of HBV is useful in identifying chronic hepatitis B patients who are at increased risk of disease progression, thereby enabling physicians to optimize antiviral therapy for these patients.

Distinct mutant hepatitis B virus genomes, with alterations in all four open reading frames, in a single South African hepatocellular carcinoma patient

Sequence variation of hepatitis B virus (HBV) can influence the replication, antigen expression and pathogenicity of the virus. We report on the mutational analysis of HBV performed in a 28-year-old Black South African female diagnosed with HBV-induced hepatocellular carcinoma. Full-genome amplification and DNA sequencing of HBV was carried out. Five distinct complete genomic clones were described with extensive genomic and intragenic variation. Phylogenetic analysis revealed that all five clones belonged to subgenotype A1 and that there were at least four virus populations with genomes of different lengths ranging from 3194 to 3253 base pairs. In this particular patient, four major characteristic features, not previously reported to occur simultaneously in HBV isolated from a single patient, were observed. Firstly, all the clones harboured a 13 base pair deletion and a 45 base pair insertion in the basic core promoter (BCP). Secondly, a 37 base pair insertion in the core gene with three adjacent single nucleotide deletions were observed. Thirdly, premature S gene stop codons were observed in some clones and lastly X gene initiation codon mutations were also observed. The complex nature of the mutations in the HBV isolated from this single patient may have contributed to the early onset of hepatocarcinogenesis.

Natural history of chronic hepatitis B in Euro-Mediterranean and African countries

Data derived from population, case-control, and cohort studies conducted in several Euro-Mediterranean and African countries disclose impressive similarities in the age and modes of hepatitis B virus (HBV) transmission and in the prevalence, duration, and outcome of the four phases of the natural history of chronic infection. Perinatal HBV infection is rare while the vast majority of chronic infections originate from horizontal HBV transmission to infants and children. HBeAg loss and seroconversion to anti-HBe occur in a few years time, usually during the second decade of life. HBeAg-negative/anti-HBe-positive chronic hepatitis B (CHB), predominates in these countries being 7-9 times more frequent than HBeAg-positive CHB. The predominance of HBeAg-negative CHB is largely linked to the molecular characteristics of HBV genotype D prevailing in European and African countries of the Mediterranean basin and of genotype E and subgenotype A1 that prevail in the other parts of Africa. The molecular characteristics of the African subgenotype A1 differ from those of European subgenotype A2 explaining the fact that patients infected subgenotype A1 demonstrate an earlier loss of HBeAg and seroconversion to anti-HBe during the natural course of HBV infection compared to those infected with subgenotype A2. It is proposed that the molecular characteristics of HBV genotypes and subgenotypes prevailing in Euro-Mediterranean and African countries acting in concert with host and environmental factors largely determine the natural history of chronic HBV infection and its significant differences from countries of HBV genotype C and B and of subgenotype Ae predominance. The knowledge of the natural history of chronic HBV infection in Euro-Mediterranean and African countries combined with wide screening programs for prompt recognition and treatment of chronic HBV infection both in its HBeAg-positive and -negative immune reactive phases can be expected to increase the efficacy of current and future therapeutic strategies.

Hepatitis B genotypes/subgenotypes and MHR variants among Moroccan chronic carriers

OBJECTIVES

The aim of this study was to determine the prevalence of Hepatitis B Virus (HBV) genotypes, subgenotypes, HBV surface antigen (HBsAg) subtypes and naturally occurring mutations in Major Hydrophilic region (MHR) of HBsAg among Moroccan patients with chronic HBV infection.

METHODS

The study included 200 patients chronically infected with HBV. The HBV genotypes, subgenotypes, HBsAg subtypes and MHR variants were determined by direct sequencing of the HBV surface (S) gene and phylogenetic analysis.

RESULTS

The S gene was successfully amplified in 134 patients. The mean age was 40.6 ± 12.2 years. Genotype D was predominant (90%, 120/134) and genotype A was less frequent (10%, 14/134). Genotype D strains belonged to subgenotypes D7 (70.8%, 85/120), D1 (25.8%, 31/120) and D2 (0.9%, 1/120). Three strains (2.5%) could not be classified in any subgenotype of genotype D. All genotype A strains belonged to subgenotype A2. HBsAg subtypes found were ayw2 (82.1%, 110/134), adw2 (10.4%, 14/134), ayw3 (3%, 4/134) and ayw4 (3%, 4/134). The global prevalence of MHR variants was 15% (20/134) with substitution P120T/S the most frequent (3.7%, 5/134). The occurrence of MHR variants was significantly associated with advancing age (>40 years) (p = 0.003) and independent of sex, HBeAg status, viral load, genotype, subgenotype and HBsAg subtype.

CONCLUSIONS

This study provides the first description of predominance of HBV subgenotype D7/subtype ayw2 among Moroccan HBV chronic carriers. It also showed a significant prevalence of naturally occurring MHR variants in Morocco.

Molecular characterization and phylogenetic analysis of full-genome HBV subgenotype D3 sequences from Serbia

Hepatitis B virus (HBV) is classified into 8 genotypes with distinct geographical distribution. Genotype D (HBV/D) has the widest distribution area and is comprised of 7 subgenotypes. Subgenotypes D1, D2 and D3 appear worldwide, while D4-D7 have a more restricted distribution. Within the Mediterranean area, HBV/D and subgenotype D3 are the most prevalent. The purpose of this study was to characterize the full genome of Serbian HBV/D3 isolates by comparison and phylogenetic analysis with HBV/D3 sequences (66 samples) found in GeneBank/DDBJ databases from different parts of the world. Isolates were obtained from three patients diagnosed with chronic hepatitis B (HBsAg+). All three isolates have two very rare nucleotide substitutions, A929T and T150A, which indicate the same ancestor. Phylogenetic analysis of HBV/D3 genome sequences throughout the world follows an ethno-geographical origin of isolates with rare exceptions, which could be explained by human travelling and migration. The geographically close but ethnically different Serbian and Italian isolates clustered in the same subnode, and on a common branch with strains from Northern Canada. To test the apparently close HBV phylogenetic relationship between completely separated patients from Serbia and Northern Canada we analyzed in depth a 440 bp region of the HBsAg from Canadian (n=73) and Serbian (n=70) isolates. The constructed parsimony tree revealed that strains from Serbia and Northern Canada fell along the same branch which indicates independent evolution within regions of each country. Considering that HBsAg sequence has limited variability for phylogenetic analyses, our hypothesis needs further confirmation with more HBV complete genome sequences.

Hepatitis B virus infection from an evolutionary point of view: how viral, host, and environmental factors shape genotypes and subgenotypes

Hepatitis B virus (HBV) has an overwhelming distribution in the world and causes important human health problems. It has infected one-third of the global population and more than 350 million people are chronic carriers. Several aspects of HBV infection confer adaptive advantages that lead to a highly efficient dissemination of the virus through different routes of transmission. HBV genotypes and subgenotypes have been associated with differences in clinical and virological characteristics, indicating that they may play a role in the virus-host relationship. In particular, a clear association between genotype A and chronic outcomes in both children and adults depending on the subgenotype involved, and between genotype C and a higher risk of complications from HBV infection, has been demonstrated. Interestingly, subgenotype A2 and genotype C are respectively likely to predominate in high-risk groups for sexual transmission and in areas where perinatal transmission is the major mode of HBV dissemination. An evolutionary approach to HBV infection, based on the principles of natural selection, may offer explanations for how modes of transmission may favor some genotypes and subgenotypes over others and, ultimately, influence HBV virulence.

Geographical and ethnic distribution of the HBV C/D recombinant on the Qinghai-Tibet Plateau

Two forms of hepatitis B virus (HBV) C/D recombinant have been identified in western China, but little is known about their geographical and ethnic distributions, and particularly the clinical significance and specific mutations in the pre-core region. To address these questions, a total of 624 chronic HBV carriers from four ethnic populations representing five provinces in western China were enrolled in this study. Genotypes were firstly determined by restriction fragment length polymorphism, and then confirmed by full or partial genome nucleotide sequencing. The distribution of HBV genotypes was as follows: HBV/B: 40 (6.4%); HBV/C: 221 (35.4%); HBV/D: 39 (6.3%); HBV/CD: 324 (51.9%). In the 324 HBV C/D recombinant infections, 244 (75.3%) were infected with the "CD1" and 80 (24.7%) were infected with the "CD2." The distribution of HBV genotypes exhibited distinct patterns in different regions and ethnic populations. Geographically, the C/D recombinant was the most prevalent HBV strain on the Qinghai-Tibet Plateau. Ethnically, the C/D recombinant had a higher prevalence in Tibetan patients than in other populations. Clinically, patients with HBV/CD1 showed significantly lower levels of serum total bilirubin than patients with HBV/C2. The prevalence of HBeAg was comparable between patients with HBV/CD1 and HBV/C2 (63.3% vs 50.0%, P = 0.118) whether patients were taken together or stratified by age into three groups (65.6% vs 58.8% in <30 years, P = 0.758; 61.9% vs 48.0% in 30-50 years, P = 0.244; 64.3% vs 33.3%, P = 0.336). Virologically HBV/CD1 had a significantly lower frequency of G1896A than HBV/C2. In conclusion, the HBV C/D recombinant is restricted to the Qinghai-Tibet Plateau in western China and is found predominantly in Tibetans. The predominance of the premature pre-core stop mutation G1896A in patients with the HBV C/D recombinant may account for the higher prevalence of HBeAg in these patients.

A study of TNF-alpha-238 and -308 polymorphisms with different outcomes of persistent hepatitis B virus infection in China

BACKGROUND

Two common functional polymorphisms in the promoter region of TNF-α located at nucleotides -238 (rs361525) and -308 (rs1800629) have been reported to regulate the expression of tumour necrosis factor alpha (TNF-α) and to be associated with hepatitis B virus (HBV) infection related diseases. However, their frequencies and associations with outcomes of HBV infection are not clear.

METHODS

We performed a genetic analysis of 956 Chinese Han subjects, who were divided into a HBV clearance group, an asymptomatic persistent infection group, a chronic hepatitis B group, two stages of liver cirrhosis (LC) groups, and three stages of hepatocellular carcinoma (HCC) groups to examine the relationship among HBV infection related diseases and these two single nucleotide polymorphisms (SNPs).

RESULTS

The phenotype of polymorphism -238 in all study samples displayed no significant differences among the eight subgroups. The distribution of -308 phenotypes among the eight groups differed significantly. For females, compared with persistent infection, LC patients had a significantly higher A allele frequency, and the association with cirrhosis progression was significant. For males, there were statistically significant differences in allele distributions between the persistent infection group and the HCC group. The AG haplotype (-A308, -G238) was associated significantly with HCC development.

CONCLUSIONS

The results of the present study indicate an association between rs1800629 and HBV related disease progression in the Chinese Han population. The association was different between genders, with the rs1800629 A allele being a risk factor for female carriers to develop LC, and the allele being a risk factor for male carriers to develop HCC, especially in subjects with an alcohol abuse or cigarette smoking history.

The natural history of chronic HBV infection and geographical differences

Although chronic HBV infection is a global health issue, there are geographical differences in the mode of transmission, prevalence and HBV genotype distribution. Chronic HBV infection is a dynamic state of interactions between HBV, hepatocytes and immune cells of the host. Accordingly, the natural history of chronic HBV infection typically starts with an immune tolerant phase, followed by an immune clearance phase and finally an inactive phase. The duration of the immune tolerant phase is usually long in chronic HBV infection acquired perinatally or in early childhood, otherwise the duration is very short. During the inactive phase, spontaneous hepatitis B surface antigen (HBsAg) seroclearance might occur at an annual rate of 1-2%; however, HBV reactivation with hepatitis activity could occur over time in one-quarter to one-third of HBsAg-seropositive patients. This occurs more frequently in males and in patients infected with genotypes D, C and B. The effort of active HBV replication-triggered immune clearance is the driving force of liver injury and subsequent disease progression in patients with hepatitis B e antigen (HBeAg)-positive or HBeAg-negative hepatitis. Clinical studies have shown that chronic HBV infection in western countries is associated with a higher incidence of cirrhosis, but lower incidence of hepatocellular carcinoma, than in Asian countries. The geographical differences in age at the time of infection and predominant HBV genotype could account for the variance in the natural history of chronic HBV infection; however, some of these differences might actually result from comparisons between cohorts with different age, gender distribution or fibrosis stage.

Secular trend of the viral genotype distribution in children with chronic hepatitis B virus infection after universal infant immunization

Genotypes B and C are the major hepatitis B virus (HBV) genotypes in Taiwan, and genotype C is associated with more severe liver disease than genotype B. Whether the implementation of the hepatitis B immunization program has affected the secular trend of the HBV genotype distribution remains unknown. We thus investigated the HBV genotypes in hepatitis B surface antigen (HBsAg)-carrier children born before the implementation of the universal infant immunization program and in those born afterward. One hundred seven children who were infected with HBV despite appropriate immunization were enrolled as immunized cases with HBV breakthrough infection. Each case was matched with two unimmunized HBsAg carriers according to the age at enrollment. HBV genotypes were determined with molecular methods. Compared with unimmunized HBsAg carriers, more immunized children had HBsAg-positive mothers (65.9% versus 100%, P < 0.001) and were infected with genotype C (16.4% versus 42.1%, P < 0.001). Among the children born to HBsAg-positive mothers, the mothers' and children's HBV genotypes were highly concordant in both unimmunized [κ = 0.97, 95% confidence interval (CI) = 0.90-1.00] and immunized children (κ = 0.97, 95% CI = 0.92-1.00). After adjustments for gender, maternal age, and delivery mode, immunized HBsAg-carrier children born to HBsAg-positive mothers had a higher likelihood of genotype C infection than unimmunized children (odds ratio = 3.03, 95% CI = 1.62-5.65, P = 0.001). However, the increased genotype C to genotype B ratio was not seen in the HBsAg-carrier mother pool in the postimmunization era.

CONCLUSION

In the postimmunization era, most HBV breakthrough infections are due to maternal transmission, and immunized children born to genotype C mothers may have a higher rate of breakthrough infection than those born to genotype B mothers.

The Role of Antiviral Therapy for HBV-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a highly prevalent and lethal cancer worldwide; despite the curative treatment for HCC, the rate of tumor recurrence after hepatectomy remains high. Tumor recurrence can occur early (<2 years) or late (>2 years) as metastases or de novo tumors. Several tumor factors were associated with HCC recurrence; high hepatitis B virus (HBV) load is the major risk factor for late recurrence of HCC after resection. Preoperative antiviral therapy improves liver function, and postoperative reduce HCC recurrence. In this paper, we focus on antiviral treatment to improve the liver function, prevent recurrence, and lengthen the overall survival for HBV-related HCC.

The clinical implications of hepatitis B virus genotype: Recent advances

Outcomes of chronic hepatitis B virus (HBV) infection are heterogeneous. Estimates of annual incidence of cirrhosis and hepatocellular carcinoma (HCC) are 2-10% and 1-3%, respectively. Several viral factors, including HBV genotype, viral load and specific viral mutations, have been associated with disease progression. Among these, HBV genotype is not only predictive of clinical outcomes but has also been associated with response to interferon treatment. Currently, at least 10 HBV genotypes and several subtypes have been identified; they have distinct geographic distribution. Acute infection with genotypes A and D results in higher rates of chronicity than genotypes B and C. Compared to genotype A and B cases, patients with genotypes C and D have lower rates of spontaneous hepatitis B e antigen (HBeAg) seroconversion; when this occurs, it tends to be delayed. HBV genotype C has a higher frequency of basal core promoter (BCP) A1762T/G1764A mutation, pre-S deletion and is associated with higher viral load than genotype B. Similarly, genotype D has a higher prevalence of BCP A1762T/G1764A mutation than genotype A. These observations suggest important pathogenic differences between HBV genotypes. These may contribute to more severe liver disease, including cirrhosis and HCC with genotypes C and D HBV infection. In addition, genotype A and B patients have better responses to interferon-based therapy than genotypes C and D, but there are few consistent differences for direct HBV antivirals. In conclusion, genotyping of chronic HBV infections can help practicing physicians identify those at risk of disease progression and determine optimal anti-viral therapy.

Treatment of children with chronic hepatitis B virus infection in the United States: patient selection and therapeutic options

Chronic hepatitis B virus (HBV) infection in children presents a therapeutic challenge for the practitioner. Decisions regarding selection of patients who may benefit from treatment, appropriate timing of treatment, and the choice of antiviral therapy are complex and are compounded by the limited number of drugs that have been studied in children. An expert panel of nationally recognized pediatric liver specialists was convened by the Hepatitis B Foundation on August 11, 2009, to consider clinical practice relative to the therapeutic options available for children. A detailed account of these discussions is provided, and the opinions expressed are based on consensus of the experts, as well as on published evidence when available. The panel concludes that, at this time, there is no established benefit of treatment of children in the immune tolerant phase, and there is a very high risk of development of drug resistance. In addition, there is no indication for treatment of children in the inactive carrier state. For children in the immune active or reactivation phases, liver histology can help guide treatment decisions, and family history of liver disease, especially hepatocellular carcinoma, may argue for early treatment in some cases. Outside of clinical trials, interferon is the agent of choice in most cases. Nucleos(t)ide analogues are secondary therapies, and children who receive these agents require careful monitoring for development of resistance. There are a few situations when treatment is indicated regardless of HBV DNA or alanine aminotransferase levels. There is still much to be elucidated about the appropriate use of HBV therapy in children. Until more clinical data and therapeutic options are available, a conservative approach is warranted.

High prevalence of hepatitis B virus genotype E in Northern Madagascar indicates a West-African lineage

The prevalence of hepatitis B virus (HBV) markers was investigated in 563 inhabitants aged 15-55 years from a sugar cane region, Sirama, and from a village, Mataipako, in Northern Madagascar. Serological markers of past or present infection were significantly higher in Sirama, 74% versus 45%. There was no difference in the prevalence of chronic HBsAg carriers, 8.7% versus 8.5% between the two regions. Sequencing the S gene in 45 strains revealed a predominance of genotype E, in 53%, followed by subgenotype A1 in 22%, and genotype D in 18%. Phylogenetic analyses of the genotype E strains showed homology with West African strains. All A1 isolates were similar to Malawi strains. Most genotype D strains were subgenotype D7 and related to strains from Somalia and Tunisia. One genotype D strain formed a branch between Pacific D4 and African D7 strains at neighbor-joining analysis. The pre-core stop mutant was found in 33% of the genotype D strains, 17% of E but not in any A1 strain. The high prevalence and low variability of genotype E strains in only two villages, indicates a rather recent introduction of this genotype into Madagascar from West Africa, possibly through migration or slave trade. The wider spread and genetic relationship of genotype D with East African and Austronesian strains indicate an earlier introduction of this genotype. Molecular epidemiology of HBV may thus be used to complement linguistic and genetic studies on past human migrations in Africa.

Molecular analysis of HBV genotypes and subgenotypes in the Central-East region of Tunisia

Background

In Tunisia, country of intermediate endemicity for Hepatitis B virus (HBV) infection, most molecular studies on the virus have been carried out in the North of the country and little is known about other regions. The aim of this study was to determine HBV genotype and subgenotypes in Central-East Tunisia. A total of 217 HBs antigen positive patients were enrolled and determination of genotype was investigated in 130 patients with detectable HBV DNA. HBV genotyping methods were: PCR-RFLP on the pre-S region, a PCR using type-specific primers in the S region (TSP-PCR) and partial sequencing in the pre-S region.

Results

Three genotypes (D, B and A) were detected by the PCR-RFLP method and two (D and A) with the TSP-PCR method, the concordance between the two methods was 93%. Sequencing and phylogenetic analysis of 32 strains, retrieved the same genotype (D and A) for samples with concordant results and genotype D for samples with discordant results. The sequences of discordant genotypes had a restriction site in the pre-S gene which led to erroneous result by the PCR-RFLP method. Thus, prevalence of genotype D and A was 96% and 4%, respectively. Phylogenetic analysis showed the predominance of two subgenotypes D1 (55%) and D7 (41%). Only one strain clustered with D3 subgenotype (3%).

Conclusions

Predominance of subgenotype D7 appears to occur in northern regions of Africa with transition to subgenotype D1 in the East of the continent. HBV genetic variability may lead to wrong results in rapid genotyping methods and sequence analysis is needed to clarify atypical results.

Molecular characterization of the Hepatitis B virus genotypes in Colombia: a Bayesian inference on the genotype F

Hepatitis B is a worldwide health problem affecting about 2 billion people and more than 350 million are chronic carriers of the virus. Nine HBV genotypes (A to I) have been described. The geographical distribution of HBV genotypes is not completely understood due to the limited number of samples from some parts of the world. One such example is Colombia, in which few studies have described the HBV genotypes. In this study, we characterized HBV genotypes in 143 HBsAg-positive volunteer blood donors from Colombia. A fragment of 1306 bp partially comprising HBsAg and the DNA polymerase coding regions (S/POL) was amplified and sequenced. Bayesian phylogenetic analyses were conducted using the Markov Chain Monte Carlo (MCMC) approach to obtain the maximum clade credibility (MCC) tree using BEAST v.1.5.3. Of all samples, 68 were positive and 52 were successfully sequenced. Genotype F was the most prevalent in this population (77%) - subgenotypes F3 (75%) and F1b (2%). Genotype G (7.7%) and subgenotype A2 (15.3%) were also found. Genotype G sequence analysis suggests distinct introductions of this genotype in the country. Furthermore, we estimated the time of the most recent common ancestor (TMRCA) for each HBV/F subgenotype and also for Colombian F3 sequences using two different datasets: (i) 77 sequences comprising 1306 bp of S/POL region and (ii) 283 sequences comprising 681 bp of S/POL region. We also used two other previously estimated evolutionary rates: (i) 2.60 × 10(-4)s/s/y and (ii) 1.5 × 10(-5)s/s/y. Here we report the HBV genotypes circulating in Colombia and estimated the TMRCA for the four different subgenotypes of genotype F.

Molecular epidemiological study of hepatitis B virus among migrant workers from Cambodia, Laos, and Myanmar to Thailand

Although hepatitis B virus (HBV) infection is endemic in Southeast Asia, molecular epidemiological data on HBV circulating in some countries are limited. The aims of this study were to evaluate the seroprevalence of HBV and its genetic variability among migrant workers from Cambodia, Laos, and Myanmar in Thailand. Sera collected from 1,119 Cambodian, 787 Laotian, and 1,103 Myanmarese workers were tested for HBsAg. HBV DNA was amplified and the pre-S/S region was sequenced for genotyping and genetic mutation analysis. HBsAg was detected in 282 (9.4%). The prevalence of HBsAg among migrant workers from Cambodia, Laos, and Myanmar was 10.8%, 6.9%, and 9.7%, respectively. Of 224 subjects positive for HBV DNA, 86% were classified as genotype C (99% were sub-genotype C1) and 11.6% were genotype B (30.8%, 34.6%, and 30.8% were sub-genotypes B2, B3, and B4, respectively). Various point mutations in the "a" determinant region were detected in approximately 18% of these samples, of which Ile126Ser/Asn was the most frequent variant. Sequencing analysis showed that 19.1% of samples had pre-S mutations, with pre-S2 deletion as the most common mutant (7.7%) followed by pre-S2 start codon mutation (3.8%) and both pre-S2 deletion and start codon mutation (3.3%). High prevalence of HBV infection (approximately 7-11%) was found among migrant workers from Cambodia, Laos, and Myanmar, which may reflect the current seroprevalence in their respective countries. The data also demonstrated that HBV sub-genotype C1 was the predominant strain and various mutations of HBV occurring naturally were not uncommon among these populations.

Do we need to determine viral genotype in treating chronic hepatitis B?

Many studies have attested that not only does HBV genotype influence the outcome of the disease but it also influences the outcome of therapy with interferons and pegylated interferons, with genotype A doing better than genotype D in Caucasians and genotype B better than genotype C in Asians. However, the guidelines from three regional bodies - AASLD, APASL and EASL - all stop short of recommending genotyping as part of the management of chronic hepatitis B. The recommendations, however, from several national organizations as well as from individual reviewers suggest that genotyping is essential to detect patients in whom the use of pegylated interferon will give a high likelihood of response with a finite course of therapy and avoid the disadvantages of nucleoside analogues with their viral resistance. It is concluded that determination of HBV genotype should form part of the management in treating chronic hepatitis B.

Natural history of chronic hepatitis B

In this article, the 4 phases of chronic HBV infection are reviewed and the factors that are associated with disease progression and the development of hepatocellular carcinoma (HCC) and cirrhosis are discussed. Also discussed is what is known to date about how to identify persons at the highest risk of developing HCC and/or cirrhosis. Finally, ways in which the natural history can be altered by hepatitis B vaccination and identification, close monitoring, and appropriate treatment of chronically infected individuals are reviewed.

Are hepatitis B virus "subgenotypes" defined accurately?

BACKGROUND

Recently, several novel hepatitis B virus (HBV) subgenotypes have been introduced that do not meet proper definition of "subgenotypes". In particular for HBV genotype A, such novel subgenotypes have been reported.

OBJECTIVE

To comprehensively reanalyse all HBV subgenotypes A, and to propose a novel, consistent alternative for HBV classification.

STUDY DESIGN

All HBV full-length genome subgenotypes A1-A6 were reanalysed using phylogenetic reconstruction and genetic distance calculation in order to study their evolutionary relationships.

RESULTS

Phylogenetic analysis based on the complete genome sequence of subgenotype A strains revealed four distinct clusters supported by high bootstrap values, whereas only the three groups A1, A2 and A6 could be assigned as subgenotypes. Previously introduced subgenotype A3, "tentative A4" and A5 clustered together in one main branch and were designated as "quasi-subgenotypes". Also genetic distances failed to classify these three groups as definite subgenotypes. These results advocate for a new classification of HBV genotype A into subgenotype A1, A2, "quasi-subgenotype A3" and A4.

CONCLUSION

Detailed phylogenetic analysis of the complete genome sequences demonstrates that some of available HBV genotype A strains may not be considered as definite "subgenotypes". These strains, which are mainly of African origin, could be considered as "quasi-subgenotypes" which puts them in between the "clade" and "subgenotype" definition. Geographical origin may have a key role in further classification of HBV subgenotypes.

Recent advances in managing hepatitis B

In the past two years, several national and international bodies have made recommendations and published updated practice guidelines for hepatitis B. In addition, new drugs have become available for treatment of hepatitis B. This article will review the new recommendations for screening for hepatitis B and for first-line antiviral medications to use for treatment. In addition, I will discuss the recent recommendations on treating hepatitis B and human immunodeficiency virus co-infection and the screening of people receiving immunosuppressive therapy.