Hepatic necroinflammation and fibrosis in patients with genotypes Ba and C, core-promoter and precore mutations

Virological, serological and clinical outcomes in chronic hepatitis B virus infection: development and validation of the HEPA-B simulation model

OBJECTIVES

Detailed simulation models are needed to assess strategies for prevention and treatment of hepatitis B virus (HBV) infection, the world's leading cause of liver disease. We sought to develop and validate a simulation model of chronic HBV that incorporates virological, serological and clinical outcomes.

METHODS

We developed a novel Monte Carlo simulation model (the HEPA-B Model) detailing the natural history of chronic HBV. We parameterised the model with epidemiological data from the Western Pacific and sub-Saharan Africa. We simulated the evolution of HBV DNA, 'e' antigen (HBeAg) and surface antigen (HBsAg). We projected incidence of HBeAg loss, HBsAg loss, cirrhosis, hepatocellular carcinoma (HCC) and death over 10-year and lifetime horizons. We stratified outcomes by five HBV DNA categories at the time of HBeAg loss, ranging from HBV DNA<300 copies/mL to >106 copies/mL. We tested goodness of fit using intraclass coefficients (ICC).

RESULTS

Model-projected incidence of HBeAg loss was 5.18% per year over lifetime (ICC, 0.969 (95% CI: 0.728 to 0.990)). For people in HBeAg-negative phases of infection, model-projected HBsAg loss ranged from 0.78% to 3.34% per year depending on HBV DNA level (ICC, 0.889 (95% CI: 0.542 to 0.959)). Model-projected incidence of cirrhosis was 0.29-2.09% per year (ICC, 0.965 (95% CI: 0.942 to 0.979)) and HCC incidence was 0.06-1.65% per year (ICC, 0.977 (95% CI: 0.962 to 0.986)). Over a lifetime simulation of HBV disease, mortality rates were higher for people with older age, higher HBV DNA level and liver-related complications, consistent with observational studies.

CONCLUSIONS

We simulated HBV DNA-stratified clinical outcomes with the novel HEPA-B Model and validated them to observational data. This model can be used to examine strategies of HBV prevention and management.

Clearance of Hepatitis B e Antigen in Untreated Chronic Hepatitis B Virus Infection: A Systematic Review and Meta-analysis

BACKGROUND

In people with hepatitis B virus (HBV) infection, persistence of hepatitis B e antigen (HBeAg) is associated with clinical progression and need for treatment. HBeAg loss represents partial immune control and is a critical event in the natural history of chronic HBV.

METHODS

We conducted a systematic review and meta-analysis of cohort studies that report HBeAg loss among people with untreated chronic HBV. We evaluated HBeAg loss using a random-effects model and conducted subanalysis on region.

RESULTS

We screened 10 560 publications, performed 196 full-text analyses, and included 26 studies for meta-analysis. The pooled rate of HBeAg loss was 6.46/100 person-years (PYs) (95% confidence interval, 5.17-8.08). Meta-regression showed that older age of participants and studies in Europe were associated with higher rate of HBeAg loss. Rates per 100 PYs were 7.43 (95% confidence interval, 6.30-8.75; 1 study) in Africa, 3.24 (2.61--4.02; 1 study) in the Eastern Mediterranean, 13.67 (11.21-16.66; 4 studies) in Europe, 7.34 (4.61--11.70; 5 studies) in North America, and 5.53 (4.05--7.55; 15 studies) in the Western Pacific.

CONCLUSIONS

Spontaneous HBeAg loss occurs at a rate of 6.46/100 PYs. Variations by region and age group may reflect epidemiological, immunological, or HBV genotype-related differences.

Epidemiology, Genotyping, Mutational and Phylogenetic Analysis of Hepatitis B Virus Infection in North-east India

BACKGROUND/OBJECTIVE

Hepatitis B virus (HBV) infection is a major public health problem globally. Northeast India is home to indigenous tribes with different ethnicity and high rates of drug abuse and HIV infection. The study was designed to estimate the burden of HBV infection across various spectrums of liver diseases from this region. HBV genotypes and subgenotypes play a role in the chronicity of disease, response to treatment and its progression. As very limited data are available from this region, we tried to elucidate the role of HBV genotypes, HBV mutants and their phylogenetic analysis.

METHOD

We designed a prospective multicentric study, and included 7464 liver disease cases, 7432 blood donors and 650 health care workers, who were screened for HBV infection. HBV DNA positive patients were genotyped and subjected to surface protein, precore and core mutation and phylogenetic analysis.

RESULTS

The prevalence of HBV infection with respect to different types of liver diseases, blood donors and health care workers was 9.9% (1550/15,546). 49.5% (768/1550) cases were found to be HBV DNA positive. The most common genotype was found to be genotype D 74.2% (570/768), followed by genotype C 6.5% (50/768), A 4.4% (34/768) and I 0.9% (7/768).

CONCLUSION

This study highlights the high hepatitis B burden in Northeast India, reflecting lacunae in health care needs of the region. Also, the different genotype distribution and presence of mutations may translate into different rates of liver disease progression, prognosis and ultimately, clinical significance. However, further prospective cohort study from Northeast India is warranted, to elucidate the clinical significance of multiple genotypes and mutation in this unique population.

The virological aspects of hepatitis B

Human hepatitis B virus (HBV) is a hepatotropic virus that is responsible for a significant burden of disease, causing liver disease and hepatocellular carcinoma. It is a small DNA virus with a replication strategy that is similar to that of a retrovirus. HBV is prone to mutagenesis and under the influence of diverse selection pressures, has evolved into a pool of quasispecies, genotypes and mutants, which confers a significant survival advantage. The genome is small, circular, and compact but has a complex replication strategy. The viral life cycle involves the formation of a covalently closed circular DNA (cccDNA), which is organized into a minichromosome that is the template for the synthesis of viral mRNA. HBV DNA (double-stranded linear form) can also integrate into the host genome, ensuring lifelong persistence of the virus. To date, despite great advances in therapeutics, once HBV is chronically established, it is incurable. This is by virtue of many aspects of its virological structure and viral life cycle. In this review, we aim to discuss important aspects of the virology of HBV with a focus on clinical implications.

High rate of core promoter and precore mutations in patients with chronic hepatitis B

Background

The prevalence of precore (PC) and core promoter (CP) mutations in patients with chronic hepatitis B virus (HBV) infection (CHB) and their impact on liver disease is incompletely defined in the United States.

Methods

A retrospective chart review using a cross-sectional approach of 1,186 CHB patients was conducted.

Results

Of 926 patients tested for HBV e antigen (HBeAg), 37 % were HBeAg+. Of 194 patients tested for mutations, 80 % had PC or CP mutations or both; 89 % of HBeAg-negative and 56 % of HBeAg+ patients had PC or CP mutations or both (p < 0.001). The mean log₁₀ ALT was significantly lower in patients with both mutations compared to patients without mutations. The mean log₁₀ HBV DNA was significantly lower in patients with only PC mutations (4.82) compared to patients without mutations (5.71, p = 0.019). With the study population divided into four subgroups based on ALT level at time of diagnosis, cirrhosis incidence was significantly higher in patients with ALT 1–2 × ULN and ALT > 2 × ULN compared to patients with ALT ≤ 0.5 × ULN.

Conclusions

Our finding that PC and CP mutations may be associated with milder liver disease in some patients could serve as the basis for longitudinal studies to help delineate treatment need and duration in patients with these mutations. If confirmed, the finding of an association between ALT 1–2 × ULN and increased incidence of cirrhosis could call into question guidelines which only recommend treatment with ALT > 2 × ULN.

Decreasing hepatitis B viral load is associated with a risk of significant liver fibrosis in hepatitis B e antigen positive chronic hepatitis B

Alanine aminotransferase (ALT), hepatitis B virus (HBV) DNA levels and age are used commonly to assess liver histology in chronic hepatitis B. Increasing levels of HBV DNA are associated with the increasing prevalence of significant fibrosis in HBeAg-negative patients. It is unclear whether these data can be applied to HBeAg-positive patients. In present study, liver biopsies were performed and clinical parameters were measured in 234 treatment-naive chronic HBeAg-positive patients. The proportion of significant fibrosis in patients with ALT 1-2 × ULN was similar to in patients with ALT more than 2 × ULN (48.4% vs. 51.8%). Patients over 30 years of age (>30 years) had a higher prevalence of significant fibrosis than patients 30 years of age and younger (61.0% vs. 33.6%). Negative correlation between HBV DNA levels and significant fibrosis was observed in patients >30 years. The optimal level of serum HBV DNA to evaluate low risk of significant fibrosis was ≥6.7 log10 IU/ml. Patients with serum HBV DNA levels ≥8.5 log10 IU/ml all had no significant fibrosis, however, patients with HBV DNA levels <4.7 log10 IU/ml all had significant fibrosis. Logistic regressions showed that age, aspartate aminotransferase, platelet count, and HBV DNA levels were independent predictors of significant fibrosis. In summary, older age, elevated ALT, and lower HBV DNA levels are associated with significant fibrosis. Decreasing levels of HBV DNA are associated with increasing prevalence of significant fibrosis in patients >30 years. The threshold of HBV DNA levels for treatment of HBeAg-positive patients needs to be combined with age.

HBeAg negative variants and their role in the natural history of chronic hepatitis B virus infection

Molecular virology methods including polymerase chain reaction, cloning and sequencing have revolutionised our understanding of viral genome variation. In the case of hepatitis B virus (HBV), sequencing studies have identified a number of virus variants normally found during the natural course of chronic infection. The appearance of the precore stop codon (with G-for-A substitution at position 1896) and basal core promoter (BCP) (with A-for-T and G-for-A, at positions 1762 and 1764, respectively) variants which reduce or abrogate hepatitis B e antigen (HBeAg) production, heralds the initiation of the seroconversion phase from HBeAg to anti-HBe positivity. The gradual removal of the tolerogenic effect of HBeAg leads to the awakening of the immune response (immune clearance phase). Most patients after HBeAg seroconversion become “inactive HBsAg carriers”. However during the course of infection precore and/or BCP variants may emerge and be selected leading to HBeAg negative chronic hepatitis B (CHB) with high viremia levels (reactivation phase). The prevalence of HBeAg negative CHB has been increasing over the last few decades and has become the commonest type of HBV infection in many countries of the world. This probably reflects the aging of existing HBV carriers and the effective prevention measures restricting new HBV infections. Frequent acute exacerbations accompanied by high viral replication, elevated alanine aminotransferase levels and histological activity are a common feature of HBeAg negative CHB leading to cirrhosis much faster than in HBeAg positive CHB patients.

Parameters associated with significant liver histological changes in patients with chronic hepatitis B

This study aimed to evaluate factors associated with significant liver histological changes. Liver biopsies from 157 CHB patients were retrospectively analyzed. Only ALB was significantly correlated with advanced liver necroinflammatory (P = 0.001). Age, ALB, GLOB, AST, PLT, and PT were independent predictors of significant fibrosis (P = 0.002, P < 0.001, P = 0.001, P = 0.048, P < 0.001, and P = 0.001, resp.). AST, WBC, and HBV DNA were significantly correlated with advanced fibrosis in normal ALT patients (P < 0.001, P = 0.041, and P = 0.012, resp.) and age, ALB, GLOB, PLT, and PT in patients with abnormal ALT (P = 0.003, P < 0.001, P = 0.004, P < 0.001, and P = 0.002, resp.). Age, AST, GGT, PLT, and PT were significantly associated with advanced fibrosis in HBeAg+ patients (P = 0.01, P = 0.016, P = 0.027, P = 0.016, and P = 0.009, resp.) and ALB, GLOB, WBC, PLT, and PT in HBeAg− patients (P < 0.001, P = 0.004, P = 0.005, P < 0.001, and P = 0.035, resp.). PLT was an excellent predictor for cirrhosis (P < 0.001 and AUROC = 0.805). ALT was not predictive of advanced fibrosis for patients with HBeAg+ or HBeAg− (P = 0.273 and P = 0.599, resp.). PLT was an excellent predictor for cirrhosis in CHB patients. Liver histopathology can be recommended for chronic HBV carriers of older age, with normal ALT, lower PLT, and lower ALB.

Precore and basal core promoter mutations in Asian American patients with hepatitis B e antigen-positive chronic hepatitis B

BACKGROUND

Prior studies have shown that precore mutations abolish and basal core promoter (BCP) mutations down-regulate hepatitis B e antigen (HBeAg) production. Thus, the presence of precore and BCP mutations in HBeAg-positive patients indicates an infection with a mixed viral population of wild-type and precore and/or BCP mutant hepatitis B virus (HBV). To date, there has been limited study of the prevalence and clinical significance of precore and BCP mutations in patients with HBeAg-positive chronic hepatitis B.

AIM

To determine the prevalence, predictors and clinical characteristics of mixed wild-type and precore/BCP HBV infection, through a cross-sectional study, in a US cohort of patients with chronic hepatitis B.

METHODS

We conducted a retrospective study of 828 chronic hepatitis B patients with HBV genotype and mutation panel testing seen at three US gastroenterology and liver clinics from June 2005 to September 2009.

RESULTS

A majority of our patients (92.3%) were either Vietnamese or Chinese American. In the HBeAg-positive cohort, 17% of patients had precore mutations only, 28% had BCP mutations only and 5% had both BCP and precore mutations. On multivariate analyses, HBV genotype C, increasing age, lower HBV DNA level and an ALT quotient >2 were independent predictors for the presence of precore and/or BCP mutations.

CONCLUSIONS

The current distinction and management recommendations for HBeAg-positive vs. HBeAg-negative patients with chronic hepatitis B should be reassessed. Additional biomarkers and treatment endpoints should be studied for their usefulness in predicting continued viral suppression after treatment discontinuation.

High hepatitis B surface antigen levels predict insignificant fibrosis in hepatitis B e antigen positive chronic hepatitis B

Introduction

There is no data on the relationship between hepatitis B surface antigen (HBsAg) levels and liver fibrosis in hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis B (CHB).

Methods

Serum HBsAg and HBV DNA levels in HBeAg-positive CHB patients with liver biopsies were analyzed. The upper limit of normal (ULN) of alanine aminotransferase (ALT) was 30 and 19 U/L for men and women respectively. Histologic assessment was based on Ishak fibrosis staging for fibrosis and Knodell histologic activity index (HAI) for necroinflammation.

Results

140 patients (65% male, median age 32.7 years) were recruited. 56 (40%) had ALT ≤2×ULN. 72 (51.4%) and 42 (30%) had fibrosis score ≤1 and necroinflammation grading ≤4 respectively. Patients with fibrosis score ≤1, when compared to patients with fibrosis score >1, had significantly higher median HBsAg levels (50,320 and 7,820 IU/mL respectively, p<0.001). Among patients with ALT ≤2×ULN, serum HBsAg levels achieved an area under receiver operating characteristic curve of 0.869 in predicting fibrosis score ≤1. HBsAg levels did not accurately predict necroinflammation score. HBsAg ≥25,000 IU/mL was independently associated with fibrosis score ≤1 (p = 0.025, odds ratio 9.042).Using this cut-off HBsAg level in patients with ALT ≤2×ULN, positive and negative predictive values for predicting fibrosis score ≤1 were 92.7% and 60.0% respectively. HBV DNA levels had no association with liver histology.

Conclusion

Among HBeAg-positive patients with ALT ≤2×ULN, high serum HBsAg levels can accurately predict fibrosis score ≤1, and could potentially influence decisions concerning treatment commencement and reduce the need for liver biopsy.

A large population histology study showing the lack of association between ALT elevation and significant fibrosis in chronic hepatitis B

OBJECTIVE

We determined the association between various clinical parameters and significant liver injury in both hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients.

METHODS

From 1994 to 2008, liver biopsy was performed on 319 treatment-naïve CHB patients. Histologic assessment was based on the Knodell histologic activity index for necroinflammation and the Ishak fibrosis staging for fibrosis.

RESULTS

211 HBeAg-positive and 108 HBeAg-negative patients were recruited, with a median age of 31 and 46 years respectively. 9 out of 40 (22.5%) HBeAg-positive patients with normal ALT had significant histologic abnormalities (necroinflammation grading ≥ 7 or fibrosis score ≥ 3). There was a significant difference in fibrosis scores among HBeAg-positive patients with an ALT level within the Prati criteria (30 U/L for men, 19 U/L for women) and patients with a normal ALT but exceeding the Prati criteria (p = 0.024). Age, aspartate aminotransferase and platelet count were independent predictors of significant fibrosis in HBeAg-positive patients with an elevated ALT by multivariate analysis (p = 0.007, 0.047 and 0.045 respectively). HBV DNA and platelet count were predictors of significant fibrosis in HBeAg-negative disease (p = 0.020 and 0.015 respectively). An elevated ALT was not predictive of significant fibrosis for HBeAg-positive (p = 0.345) and -negative (p = 0.544) disease. There was no significant difference in fibrosis staging among ALT 1-2 × upper limit of normal (ULN) and > × 2 ULN for both HBeAg-positive (p = 0.098) and -negative (p = 0.838) disease.

CONCLUSION

An elevated ALT does not accurately predict significant liver injury. Decisions on commencing antiviral therapy should not be heavily based on a particular ALT threshold.

Clinical and virological characteristics of chronic hepatitis B with concurrent hepatitis B E antigen and antibody detection

The concurrent detection of hepatitis B e antigen (HBeAg) and its corresponding antibody (anti-HBe) in patients with chronic hepatitis B virus (HBV) infection is well established but the clinical features remain poorly understood. Demographic information, clinical and laboratory data were collected from 1624 consecutive inpatient records of patients with chronic hepatitis B. Viral genotype, basic core promoter and precore mutations were determined by direct sequencing. In vitro HBeAg and anti-HBe binding experiments were conducted with three pairs of HBeAg-positive and anti-HBe-positive serum samples, which were mixed at variable ratios and incubated at 37°C for 3-24h. Of the 1624 chronic patients, 169 (10.4%) had concurrent HBeAg and anti-HBe positivity, and this was associated with intermediate age and HBV-DNA load, higher alanine aminotransferase level and more pronounced liver damage compared with HBeAg-positive or anti-HBe-positive patients alone. HBeAg and anti-HBe titres (median and interquartile range, S/CO) in the concurrent positive group were 4.2 (1.8-9.6) and 0.54 (0.27-0.72), which were closer to their respective cut-off values than those of HBeAg-positive or anti-HBe-positive groups alone. For the cases successfully sequenced, 110/134 (82.1%) harboured T1762/A1764 or/and A1896 mutants. The binding experiments showed that HBeAg and anti-HBe could be concurrently observed provided an optimal ratio (HBeAg to anti-HBe) was chosen. In antiviral treatment-naive patients, concurrence of HBeAg and anti-HBe was not uncommon, and such patients had profound liver disease. An optimal ratio between HBeAg and anti-HBe led to their concurrent detection when sera were tested by sensitive assays.

Long-term use of entecavir in nucleoside-naïve Japanese patients with chronic hepatitis B infection

BACKGROUND & AIMS

To evaluate the long-term efficacy of entecavir in nucleoside-naïve chronic hepatitis B patients.

METHODS

One hundred and sixty-seven patients treated with entecavir 0.01mg, 0.1mg or 0.5mg for 24-52weeks in Phase II studies entered rollover study ETV-060 and received entecavir 0.5mg daily. Responses were evaluated among patients with available samples.

RESULTS

After 96weeks in ETV-060 (120-148weeks total entecavir treatment time), 88% (127/144) of patients had HBV-DNA <400 copies/ml; 90.1% (128/142) had alanine aminotransferase (ALT) 1x the upper limit of normal (ULN) among those with abnormal baseline ALT; and 26% (32/121) achieved HBe seroconversion among those HBeAg(+) at baseline. A subset of 66 patients received entecavir 0.5mg (approved dose) from Phase II baseline: at week 96 in ETV-060, 83% (48/58) had HBV-DNA <400 copies/ml, 88% (52/59) had ALT 1x ULN, and 20% (10/49) achieved HBe seroconversion. Twenty-one out of 66 patients had paired baseline and on-treatment biopsies: 100% (21/21) and 57% (12/21) demonstrated histologic improvement, and improvement in fibrosis, respectively, over 3years. The 3-year cumulative probability of resistance was 3.3% for all patients and 1.7% for the 0.5mg subset.

CONCLUSIONS

Long-term entecavir for nucleoside-naïve patients resulted in high rates of virological, biochemical, and histological response, with minimal resistance.

Hepatitis B virus variants

HBV replicates through reverse transcription of an RNA intermediate; the inherent lack of proofreading causes a high mutation frequency. Mutations in the precore and core promoter regions that abolish or reduce the production of hepatitis B e antigen occur most commonly. Patients with these HBV variants remain viremic and can develop progressive liver disease. Mutations in the core promoter region are associated with an increased risk of hepatocellular carcinoma. Exogenous selection pressure might favor certain mutations. Mutations in the HBV polymerase that confer resistance to nucleoside and nucleotide analog treatments are a major barrier to the success of therapy for hepatitis B. The development of antiviral drug resistance negates the initial treatment response and can lead to hepatitis flares and hepatic decompensation. Prompt addition of another drug to which the virus is not cross-resistant is required. Mutations in the HBV surface protein that facilitate escape from host immunity are responsible for the failure of immune prophylaxis in infants who received HBV vaccine and in liver transplant recipients who received hepatitis B immune globulin.

Natural history: the importance of viral load, liver damage and HCC

Chronic hepatitis B and hepatitis C virus infections are the major causes of liver disease, hepatocellular carcinoma (HCC) and liver-related mortality worldwide. Among factors known to influence the natural history of viral hepatitis are age at the time of infection, duration of infection, serum alanine aminotransferase (ALT) levels, male sex, alcohol consumption, and coinfections. In hepatitis B, serum HBV DNA concentration emerges as the key factor for predicting the development of liver disease. Even patients with low viraemia seem at increased risk for liver cirrhosis and HCC. Coinfections with hepatitis C, hepatitis D and/or HIV are common and are associated with a more severe liver disease. The course of chronic hepatitis C is variable, but usually fibrosis advances slowly. In addition to the better-known factors- including coinfections with HBV and HIV- progression of liver disease is adversely affected by smoking, hepatic steatosis and insulin resistance.

Role of genotype and precore/basal core promoter mutations of hepatitis B virus in patients with chronic hepatitis B with acute exacerbation

OBJECTIVE

The results of long-term, follow-up studies show that the severity and frequency of acute exacerbation of chronic hepatitis B virus (HBV) are associated with the development of liver cirrhosis in chronic HBV infection. The aim of this study was to investigate the relationship between virological factors of HBV and the severity of acute exacerbation.

MATERIAL AND METHODS

Fifty-one chronic hepatitis B patients with symptomatic acute exacerbation without antiviral therapy were enrolled in the study. Genotype of HBV was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Precore (A1896) and basal core promoter (BCP) mutations (T1762 & A1764) were determined by PCR and direct sequencing.

RESULTS

Thirty-nine patients had genotype B, 11 patients had genotype C, and 1 patient had an unclassified genotype. Thirty-two patients had precore mutation and 24 patients had BCP mutation. After adjusting for age, gender, aspartate aminotransferase (ASAT) level, albumin level, and platelet count by multiple logistic regression test, precore mutation had a protective effect on the occurrence of hepatic decompensation (p=0.046), and genotype and BCP mutations were not associated with the occurrence of hepatic decompensation.

CONCLUSIONS

HBV precore mutation may confer less severe liver disease during acute exacerbation of chronic HBV. Genotype and BCP mutations did not have a significant association with the occurrence of hepatic decompensation.

Viral hepatocarcinogenesis: from infection to cancer

Hepatocellular carcinoma (HCC) is a worldwide health issue that has started receiving attention but is still poorly understood. However, the hepatitis B virus (HBV) and the hepatitis C virus (HCV) are known to be two major causative agents of HCC. They differ in their modes of infection, their treatment options, their genomes and their carcinogenic abilities. However, both share a link with HCC through alterations of the host genome. In order to continue in our search for the mechanisms behind viral hepatocarcinogenesis, the individual entities (HBV, HCV, HCC and host), their natural history, treatment options and genomic properties must be further understood. Additionally, an understanding of the genomics, the link between the entities, is crucial for the success of the ongoing search for therapeutic options for HCC. Similar to most types of cancer, hepatocarcinogenesis is a multistep process involving different genetic alterations that ultimately lead to malignant transformation of the hepatocyte. As technology advances and research continues, the genetic changes and influences among these entities will prove essential to improved diagnostic and therapeutic options. It remains a challenge to provide a clear picture of the connection between virus and cancer. We review (i) the epidemiological link between HBV/HCV infection to HCC; (ii) prevention and control of chronic hepatitis B or C in reducing HCC risk; and (iii) genetic characters of viruses and hosts and the mechanisms associated with HCC susceptibilities, with the intention of providing a direction for future research and treatment.

Natural history of chronic hepatitis B: special emphasis on disease progression and prognostic factors

The natural history of chronic hepatitis B virus (HBV) infection and disease is complex and highly variable. We review the natural history of chronic hepatitis B with emphasis on the rates of disease progression and factors influencing the course of the liver disease. Chronic hepatitis B is characterized by an early replicative phase (HBeAg positive chronic hepatitis) and a late low or non-replication phase with HBeAg seroconversion and liver disease remission (inactive carrier state). Most patients become inactive carriers after spontaneous HBeAg seroconversion with good prognosis, but progression to HBeAg negative chronic hepatitis due to HBV variants not expressing HBeAg occurs at a rate of 1-3 per 100 person years following HBeAg seroconversion. The incidence of cirrhosis appears to be about 2-fold higher in HBeAg negative compared to HBeAg positive chronic hepatitis. In the cirrhotic patient the 5-year cumulative risk of developing hepatocellular carcinoma is 17% in East Asia and 10% in the Western Europe and the United States and the 5-year liver related death rate is 15% in Europe and 14% in East Asia. There is a growing understanding of viral, host and environmental factors influencing disease progression, which ultimately could improve the management of chronic hepatitis B.

Hepatitis B virus genotypes: natural history and implications for treatment

There are eight different genotypes named A-H. Genotypes have distinct geographic distribution in different regions of the world. There exists a difference in the disease profile between different genotypes. Genotype A compared with D, and B compared with C have earlier hepatitis B e-antigen seroconversion and less severe liver disease. However, genotypes are closely linked with core promoter and precore mutations. This may have a confounding effect on the association of genotypes with disease progression. Patients with genotype A compared with D and B compared with C have a better treatment response to IFN-alpha. However, there are no differences in the treatment response and rate of emergence of drug-resistant hepatitis B virus between different genotypes to nucleoside/nucleotide analog therapy.