Mutations in the basic core promotor and the precore region of hepatitis B virus and their selection in children with fulminant and chronic hepatitis B

Possible Association between Genetic Diversity of Hepatitis B Virus and Its Effect on the Detection Rate of Hepatitis B Virus DNA in the Placenta and Fetus

Background: The prevalence of HBV infection and HBV genotypes varies from country to country, and the role of HBV genotypes in the presence of HBV in the placenta and fetus has never been explored. This study was conducted to (1) identify HBV genotypes, and their frequencies, that infected Northern Thai pregnant women; (2) evaluate the association between HBV genotypes and the detection rate of HBV DNA in the placenta and fetus; (3) evaluate the association between specific mutations of the HBV genome and HBV DNA detection in placental tissue; and (4) identify the mutation of the HBV genome that might occur between maternal blood, placenta, and cord blood. Methods: Stored samples of the maternal blood, placental tissue, and cord blood that were collected from 145 HBsAg-positive pregnant Thai women were analyzed to identify HBV DNA. Results: Approximately 25% of infected mothers had fetal HBV DNA detection, including cases with concomitant HBV DNA detection in the placenta (77.3%). A total of 11.7% of cases with placental detection had no HBV DNA detection in the maternal blood, indicating that the placenta could be a site of HBV accumulation. Of the 31 HBV-positive blood samples detected by nested PCR, the detected strains were subgenotype C1 (77.4%), subgenotype B9 (9.7%), and subgenotype C2, B2, B4, and recombinant B4/C2 (3.2% for each). Genotype B had a trend in increased risk of placental HBV DNA detection compared to genotype C, with a relative risk of 1.40 (95% CI: 1.07-1.84). No specific point mutation had a significant effect on HBV DNA detection in placental tissue. Mutation of C454T tended to enhance HBV DNA detection in placental tissue, whereas T400A tended to have a lower detection rate. No mutation was detected in different sample types collected from the same cases. Conclusions: HBV DNA detection in the fetus was identified in approximately 25% of HBV-positive mothers, associated with the presence of HBV in the placenta in most cases. The placenta could possibly be a site of HBV accumulation. Subgenotype C1 was the most common subgenotype, followed by subgenotype B9. HBV genotype B possibly had a higher trend in intrauterine detection than HBV genotype C. Mutation is unlikely to occur during intrauterine exposure.

Analysis of hepatic fibrosis markers in the serum of chronic hepatitis B patients according to basal core promoter/precore mutants

The A1762T/G1764A double mutant in the basal core promoter (BCP) region of the hepatitis B virus (HBV) is associated with severe hepatic lesions while the G1899A mutation with the double mutant is associated with a significant reduction in the risk of severe fibrosis. This study aims to measure a number of markers in the serum of patients with chronic HBV infection and to assess relationships between these markers and BCP/precore mutants with consideration of the stage of fibrosis. The serum levels of resistin, TGF-β1, MMP-1, TIMP-1, collagen IA1 and PDGF-BB, which are markers that are known to be involved in the process of hepatic fibrosis, were assayed. The serum levels of PDGF-BB and TIMP-1, and the mutation profile were independently associated with advanced fibrosis. A higher level of TIMP-1 was associated with advanced fibrosis regardless of the mutation status, and a higher level of PDGF-BB was associated with nonsevere fibrosis in patients infected with viruses harboring the A1762T/G1764A or A1762T/G1764A/G1899A mutations. Our results suggest an impact of the A1762T/G1764A mutant on the biological pathway related to TGF-β1 and PDGF-BB. In vitro studies are needed to understand the impact of these mutants on the serum secretion of markers involved in fibrosis severity.

Acute-on-Chronic Liver Failure From Chronic-Hepatitis-B, Who Is the Behind Scenes

Acute-on-chronic liver failure (ACLF) is an acute syndrome accompanied with decompensation of cirrhosis, organ failure with high 28-day mortality rate. Systemic inflammation is the main feature of ACLF, and poor outcome is closely related with exacerbated systemic inflammatory responses. It is well known that severe systemic inflammation is an important event in chronic hepatitis B (CHB)-ACLF, which eventually leads to liver injury. However, the initial CHB-ACLF events are unclear; moreover, the effect of these events on host immunity as well as that of immune imbalance on CHB-ACLF progression are unknown. Here, we investigate the initial events of ACLF progression, discuss possible mechanisms underlying ACLF progression, and provide a new model for ACLF prediction and treatment. We review the characteristics of ACLF, and consider its plausible immune predictors and alternative treatment strategies.

Human genetic basis of fulminant viral hepatitis

In rare cases, hepatitis A virus (HAV) and hepatitis B virus (HBV) can cause fulminant viral hepatitis (FVH), characterized by massive hepatocyte necrosis and an inflammatory infiltrate. Other viral etiologies of FVH are rarer. FVH is life-threatening, but the patients are typically otherwise healthy, and normally resistant to other microbes. Only a small minority of infected individuals develop FVH, and this is the key issue to be addressed for this disease. In mice, mouse hepatitis virus 3 (MHV3) infection is the main model for dissecting FVH pathogenesis. Susceptibility to MHV3 differs between genetic backgrounds, with high and low mortality in C57BL6 and A/J mice, respectively. FVH pathogenesis in mice is related to uncontrolled inflammation and fibrinogen deposition. In humans, FVH is typically sporadic, but rare familial forms also exist, suggesting that there may be causal monogenic inborn errors. A recent study reported a single-gene inborn error of human immunity underlying FVH. A patient with autosomal recessive complete IL-18BP deficiency was shown to have FVH following HAV infection. The mechanism probably involves enhanced IL-18- and IFN-γ-dependent killing of hepatocytes by NK and CD8 T cytotoxic cells. Proof-of-principle that FVH can be genetic is important clinically, for the affected patients and their families, and immunologically, for the study of immunity to viruses in the liver. Moreover, the FVH-causing IL18BP genotype suggests that excessive IL-18 immunity may be a general mechanism underlying FVH, perhaps through the enhancement of IFN-γ immunity.

Presence of Precore (C)/C Promoter Mutants in Peripheral Blood Mononuclear Cells of Chronic Hepatitis B (CHB) Carriers During Pregnancy Does Not Correlate with Increased Risk of Liver Disease in 4 Years of Follow-Up

PURPOSE

HBV precore (PC) and basal core promoter (BCP) mutants are associated with liver disease severity, yet have been suggested to protect against HBV vertical transmission. HBV within peripheral blood mononuclear cells (PBMC) has been reported in association with intrauterine HBV infection. We analyzed HBV replication status in PBMC and PC/BCP mutants in PBMC from pregnant chronic hepatitis B (CHB) patients.

METHODS

Pregnant CHB carriers were assessed for HBeAg, HBV-DNA, ALT in second-third trimester and liver stiffness measurement (LSM) postpartum. HBV-DNA, HBV-cccDNA, and HBV-mRNA were tested in PBMC by in-house PCR. BCP/PC variants were determined by Sanger sequencing and analyzed using MEGA7.

RESULTS

In 37 CHB pregnant carriers, median age 32 years, 53% Asian, median ALT 19 versus 26 U/L, median HBV-DNA 2.6 versus 8.1 logIU/mL (untreated vs. treated), eight HBeAg⁺, with genotype 10%A, 29%B, 21%C, 10%D, 19%E, eight received tenofovir in pregnancy to reduce vertical transmission risk. HBV-DNA was detected in ~ 55% (25/45) PBMC, and PC/BCP mutations were found in 36% (9/25) and 4% (1/25), respectively. All infants received HBV immunoprophylaxis and tested HBV surface antigen negative at 9-12 months of age. During a median 4 years (IQR 3-5), follow-up all mothers showed normal LSM, with no significant change in ALT, HBeAg status, or HBV-DNA levels compared to baseline in untreated CHB carriers.

CONCLUSION

In this multiethnic cohort of pregnant CHB carriers, HBV replicative intermediates and PC/BCP mutants were found in significant proportion of PBMC, but were not associated with increased risk of HBV immunoprophylaxis failure or liver disease severity over long-term follow-up.

Successful Treatment of a South African Pediatric Case of Acute Liver Failure Caused by Perinatal Transmission of Hepatitis B

We report on the successful treatment of a South African infant with hepatitis B virus (HBV)-induced acute liver failure using lamivudine with no evidence of clinical resistance. Perinatal HBV transmission occurred despite timely HBV vaccination at 6, 10 and 14 weeks, as per South African vaccination schedule, highlighting the need to introduce the birth-dose HBV vaccine in South Africa.

Role of humoral immunity against hepatitis B virus core antigen in the pathogenesis of acute liver failure

Hepatitis B virus (HBV)-associated acute liver failure (ALF) is a dramatic clinical syndrome leading to death or liver transplantation in 80% of cases. Due to the extremely rapid clinical course, the difficulties in obtaining liver specimens, and the lack of an animal model, the pathogenesis of ALF remains largely unknown. Here, we performed a comprehensive genetic and functional characterization of the virus and the host in liver tissue from HBV-associated ALF and compared the results with those of classic acute hepatitis B in chimpanzees. In contrast with acute hepatitis B, HBV strains detected in ALF livers displayed highly mutated HBV core antigen (HBcAg), associated with increased HBcAg expression ex vivo, which was independent of viral replication levels. Combined gene and miRNA expression profiling revealed a dominant B cell disease signature, with extensive intrahepatic production of IgM and IgG in germline configuration exclusively targeting HBcAg with subnanomolar affinities, and complement deposition. Thus, HBV ALF appears to be an anomalous T cell-independent, HBV core-driven B cell disease, which results from the rare and unfortunate encounter between a host with an unusual B cell response and an infecting virus with a highly mutated core antigen.

Core gene insertion in hepatitis B virus genotype G functions at both the encoded amino acid sequence and RNA structure levels to stimulate core protein expression

Hepatitis B virus genotype G possesses a 36-nucleotide (nt) insertion at the 5' end of core gene, adding 12 residues to core protein. The insertion markedly increased core protein level irrespective of viral genotype, with the effect reproducible using CMV-core gene construct. Here we used such expression constructs and transient transfection experiments in Huh7 cells to identify the structural bases. The insertion is predicted to create a stem-loop structure 14nt downstream of core gene AUG. A + 1 or + 2 frameshift into the 36nt mitigated enhancement of core protein level. Point mutations to disrupt or restore the stem-loop had opposite effects on core protein expression. Shifting the translation initiation site downstream or further upstream of the stem-loop rendered it inhibitory or no longer stimulatory of core protein expression. Therefore, both the reading frame and a properly positioned stem-loop structure contribute to marked increase in core protein expression by the 36-nt insertion.

Sanger sequencing versus INNO-LiPA® HBV PreCore assay for routine detection of precore and basal core promoter mutations in hepatitis virus B chronically infected patients

We compared the Sanger sequencing and the commercial INNO-LiPA® HBV assay for the routine detection of precore (PC) and basal core promoter (BCP) mutations of hepatitis B virus in chronically infected patients. The overall agreement rate between assays was 94.2% and 98.8% for the detection of PC and BCP mutations, respectively.

Quantifying perinatal transmission of Hepatitis B viral quasispecies by tag linkage deep sequencing

Despite full immunoprophylaxis, mother-to-child transmission (MTCT) of Hepatitis B Virus still occurs in approximately 2–5% of HBsAg positive mothers. Little is known about the bottleneck of HBV transmission and the evolution of viral quasispecies in the context of MTCT. Here we adopted a newly developed tag linkage deep sequencing method and analyzed the quasispecies of four MTCT pairs that broke through immunoprophylaxis. By assigning unique tags to individual viral sequences, we accurately reconstructed HBV haplotypes in a region of 836 bp, which contains the major immune epitopes and drug resistance mutations. The detection limit of minor viral haplotypes reached 0.1% for individual patient sample. Dominance of “a determinant” polymorphisms were observed in two children, which pre-existed as minor quasispecies in maternal samples. In all four pairs of MTCT samples, we consistently observed a significant overlap of viral haplotypes shared between mother and child. We also demonstrate that the data can be potentially useful to estimate the bottleneck effect during HBV MTCT, which provides information to optimize treatment for reducing the frequency of MTCT.

Prevalence and Characteristics of Precore Mutation in Iran and Its Correlation with Genotypes of Hepatitis B

Introduction

Mutation of the HBV precore gene prevents the production of HBeAg, which is an important target for immune responses. Distribution of this mutation varies along with frequency of HBV genotypes in accordance with geographic and ethnic variations. The general objective of this study was to evaluate the prevalence and characteristics of precore mutation in Iran and its correlation with genotypes of hepatitis B.

Methods

In this cross-sectional study, viral DNA of 182 Iranian hepatitis B surface antigen positive patients who were admitted to Bandar Abbas Blood Transfusion Organization in 2012 and 2013 was retrieved from their serum samples. HBeAg, anti-HBe, and anti-HBc IgM diagnostic tests were performed using ELISA kits. Precore and Pre-S regions were amplified using specific primers and PCR thereafter to determine the genotypes; precore mutation, PCR, and restriction fragment length polymorphism (RFLP) methods also were applied. SPSS version 12 was used for data analysis by Mann–Whitney U test, Fisher’s exact probability test, and t-test.

Results

A total of 62 patients (34.1%) had precore mutation (A1896G), and genotype D was the predominant genotype in these patients, which was followed by an unknown genotype that was suspected for genotype B. Interestingly, the relationships between precore mutation and HBeAg (p=0.037) and genotype D (p=0.005) were significant; however, no correlation was observed between this mutation and acute or chronic hepatitis and sex of patients.

Conclusion

This study found high prevalence of precore mutations in southern Iran, which was significantly associated with HBeAg and genotype D.

Peripartum cytokine flares in a multiethnic cohort of chronic hepatitis B carriers does not correlate with hepatitis B virus suppression or increased risk of liver disease

PROBLEM

In chronic hepatitis B (CHB) carriers, alanine transaminase (ALT) flares are common in the peripartum period. There are limited data on immunological changes of pregnancy in CHB. We hypothesize that in pregnant CHB carriers, the Th1/Th2 cytokine ratio is altered resulting in changes in biochemical/virological and liver fibrosis markers.

STUDY METHODS

Serum from 38 pregnant/post-partum CHB carriers (median age 32 years, 53% Asian, 8 HBeAg⁺ ) was tested for HBV DNA, quantitative HBV surface antigen, ALT and liver fibrosis by transient elastography (TE). Serum cytokines were analyzed using a Luminex assay.

RESULTS

Untreated CHB cases had mild ALT flares post-partum, but showed normal TE, and no change in viral markers despite increased Th1 cytokines compared to healthy controls (P<.05).

CONCLUSION

CHB carriers show increased Th1 cytokines in the peripartum period albeit with no effect on viral load or liver disease suggesting an aborted antiviral immune response.

Quasispecies characteristics in mother-to-child transmission of hepatitis B virus by next-generation sequencing

OBJECTIVES

To identify within-host quasispecies characteristics of hepatitis B virus (HBV) in mothers and children infected via mother-to-child transmission (MTCT).

METHODS

Using next-generation sequencing (NGS), we analyzed sequences within the non-overlapping pre-core/core (pre-C/C) gene in 37 mother-child pairs.

RESULTS

Phylogenetic and Highlighter analyses suggested that both a single strain and multiple distinct strains may be transmitted in MTCT of HBV. However, analysis of reassembled viral sequences revealed a relatively narrow distribution of variants in children, which was confirmed by a lower viral diversity in children than that in mothers. New closely related variants with combinations of two to five high-frequency mutations were observed in seven children with elevated ALT levels; the new variants out-competed the transmitted maternal variants to become the dominant strains in five of them. Furthermore, 30 mutations with a frequency >1% of all viruses within-host were present in those children; the mutations caused 19 amino-acid substitutions. Interestingly, almost all were located within the well-known T-cell or B-cell epitopes.

CONCLUSIONS

There are restrictive changes that occur in the early stages of chronic HBV infection through MTCT with different clinical consequences. These data might have important implications for future investigations of interrelated immunopathogenesis and therapeutic strategies.

Prodromal fever indicates a high risk of liver failure in acute hepatitis B

OBJECTIVES

The role of prodromal fever in the clinical course of acute hepatitis B virus (HBV) infection is still largely unclear. This study was conducted to investigate the factors associated with prodromal fever and its role in the development of acute liver failure (ALF) in patients with acute hepatitis B (AHB).

METHODS

Inpatients with AHB diagnosed between January 2006 and December 2010 were evaluated and followed. Clinical manifestations, results of laboratory tests, and outcomes were compared between patients with and without prodromal fever. The diagnosis of AHB was based on the discrete onset of symptoms, jaundice, abnormal liver function tests, the detection of high-titer IgM antibody to hepatitis B core antigen (anti-HBc), and a compatible clinical history.

RESULTS

A total of 618 AHB inpatients were identified during the study period, of whom 102 (16.5%) had prodromal fever and 41 (6.6%) developed ALF. Prodromal fever indicated more severe liver injury and was independently associated with hepatitis B e antigen (HBeAg) negativity. The occurrence of ALF was more common in febrile patients than in non-febrile patients (18.6% vs. 4.3%, p<0.001). Multivariate logistic regression showed prodromal fever and temperature >38.0°C to be independently associated with the risk of ALF, with an odds ratio (95% confidence interval) of 3.5 (1.4-8.6) and 7.1 (2.6-19.7), respectively.

CONCLUSIONS

AHB patients with prodromal fever, which is associated with a lack of HBeAg due to HBV mutation, are at high risk of ALF. Febrile patients with AHB should be managed with particular care.

Hepatitis B immunopathogenesis and immunotherapy

Worldwide there are over 248 million chronic carriers of HBV of whom about a third eventually develop severe HBV-related complications. Due to the major limitations of current therapeutic approaches, the development of more effective strategies to improve therapeutic outcomes in chronic hepatitis B (CHB) patients seems crucial. Immune activation plays a critical role in spontaneous viral control; therefore, new modalities based on stimulation of the innate and adaptive immune responses could result in the resolution of infection and are promising approaches. Here, we summarize the HBV immunopathogenesis, and discuss the encouraging results obtained from the promising immune-based innovations, such as therapeutic vaccination, cytokine therapy, cell-based therapies and blocking inhibitory receptors, as current and future immunotherapeutic interventions.

Different precore/core mutations of hepatitis B interact with, limit, or favor liver fibrosis severity

BACKGROUND AND AIM

The impact of basal core promoter (BCP) and precore (PC) mutants of the hepatitis B virus (HBV) on liver disease severity remains controversial. The aim of the present study was to screen BCP and PC mutations in 252 HBV surface antigen (HBsAg) positive carriers in France and to assess relationships between these mutations and severe fibrosis.

METHODS

Direct sequencing of the precore/core gene was used to detect A1762T/G1764A and G1757A mutations in the BCP and G1896A and G1899A mutations in the PC region.

RESULTS

The prevalences of A1762T/G1764A, G1757A, G1896A, and G1899A mutations were 34.1%, 38.7%, 54.9%, and 29.3% (P < 0.001), respectively. The independent predictors of severe fibrosis (≥F3 Metavir) were older age (P < 0.001), male gender (P = 0.012), elevated alanine aminotransferase (P < 0.001), and the double A1762T/G1764A mutant with no other mutations (P = 0.011). Interestingly, the association of the G1899A mutation with the double A1762T/G1764A mutant significantly counteracted the deleterious effect of the sole double A1762T/G1764A mutant (odds ratio [OR] = 0.28 vs. OR = 3.55, respectively, P = 0.028).

CONCLUSIONS

Patients with the A1762T/G1764A mutation have a higher risk of severe fibrosis. The G1899A mutation is a protective factor against severe fibrosis that counteracted the deleterious effect of the A1762T/G1764A mutation. Finally, host phenotypic and HBV genotypic markers independently predict fibrosis severity.

Overview of hepatitis B viral replication and genetic variability

Chronic infection with hepatitis B virus (HBV) greatly increases the risk for liver cirrhosis and hepatocellular carcinoma (HCC). HBV isolates worldwide can be divided into ten genotypes. Moreover, the immune clearance phase selects for mutations in different parts of the viral genome. The outcome of HBV infection is shaped by the complex interplay of the mode of transmission, host genetic factors, viral genotype and adaptive mutations, as well as environmental factors. Core promoter mutations and mutations abolishing hepatitis B e antigen (HBeAg) expression have been implicated in acute liver failure, while genotypes B, C, subgenotype A1, core promoter mutations, preS deletions, C-terminal truncation of envelope proteins, and spliced pregenomic RNA are associated with HCC development. Our efforts to treat and prevent HBV infection are hampered by the emergence of drug resistant mutants and vaccine escape mutants. This paper provides an overview of the HBV life cycle, followed by review of HBV genotypes and mutants in terms of their biological properties and clinical significance.

Management of mother-to-child transmission of hepatitis B virus: Propositions and challenges

Chronic hepatitis B virus (HBV) infection due to mother-to-child transmission (MTCT) during perinatal period remains an important global health problem. Despite standard passive-active immunoprophylaxis with hepatitis B immunoglobulin (HBIG) and hepatitis B vaccine in neonates, up to 9% of newborns still acquire HBV infection, especially these from hepatitis B e antigen (HBeAg) positive mothers. Management of HBV infection in pregnancy still need to draw careful attention because of some controversial aspects, including the failure of passive-active immunoprophylaxis in a fraction of newborns, the effect and necessity of periodical hepatitis B immunoglobulin (HBIG) injection to the mothers, the safety of antiviral prophylaxis with nucleoside/nucleotide analogs, the benefit of different delivery ways, and the safety of breastfeeding. In this review, we highlight these unsettled issues of preventive strategies in perinatal period, and we further aim to provide an optimal approach to the management of preventing MTCT of HBV infection.

Genetic variation of hepatitis B virus and its significance for pathogenesis

Hepatitis B virus (HBV) has a worldwide distribution and is endemic in many populations. Due to its unique life cycle which requires an error-prone reverse transcriptase for replication, it constantly evolves, resulting in tremendous genetic variation in the form of genotypes, sub-genotypes, and mutations. In recent years, there has been considerable research on the relationship between HBV genetic variation and HBV-related pathogenesis, which has profound implications in the natural history of HBV infection, viral detection, immune prevention, drug treatment and prognosis. In this review, we attempted to provide a brief account of the influence of HBV genotype on the pathogenesis of HBV infection and summarize our current knowledge on the effects of HBV mutations in different regions on HBV-associated pathogenesis, with an emphasis on mutations in the preS/S proteins in immune evasion, occult HBV infection and hepatocellular carcinoma (HCC), mutations in polymerase in relation to drug resistance, mutations in HBV core and e antigen in immune evasion, chronicalization of infection and hepatitis B-related acute-on-chronic liver failure, and finally mutations in HBV x proteins in HCC.

Lamivudine Resistance and Precore Variants in Iranian Patients With Chronic Hepatitis B: Correlation With Virological and Clinical Features

Background:

Long-term lamivudine therapy, despite its initial effectiveness against hepatitis B virus (HBV), is associated with the emergence of drug resistance mutations in polymerase protein.

Objectives:

The aim of the present study was to determine the prevalence of precore and lamivudine drug resistance mutations in lamivudine treated patients with chronic B hepatitis.

Patients and Methods:

Sequential sera were obtained from 88 chronic HBV carriers who received lamivudine for more than 24 months. Polymerase and precore regions were directly sequenced for these groups: I (before treatment), II, and III (12 and 24 months after treatment, respectively).

Results:

All patients (100%) were contained genotype D, subtype ayw2. One (1.1%), 12 (13.6%), and 22 (25%) members of groups I, II, and III had the replacement of either isoleucine or valine instead of methionine in tyrosine-methionine-aspartate-aspartate (YMDD) motif, respectively. The frequency of mutations from 0 time point to 12 and 24 months showed that there was an increasing trend between sequential samples (P < 0.001). In group I, 31 (35.2%); II, 36 (41.0%) and III, 41 (46.6%) members had the precore stop codon mutations. The frequency of mutations from 0 time point to 12 and 24 months showed that there was an ascending trend between sequential samples. Indeed, frequency of precore stop codon was significantly increased with the passage of time (P < 0.001).

Conclusions:

Presence of drug resistance mutations among the patients was significant. Precore mutations were common amongst Iranian HBV chronic carriers under lamivudine therapy and these mutations were accompanied by clinical relapse.

Deep sequencing analysis of HBV genotype shift and correlation with antiviral efficiency during adefovir dipivoxil therapy

Background

Viral genotype shift in chronic hepatitis B (CHB) patients during antiviral therapy has been reported, but the underlying mechanism remains elusive.

Methods

38 CHB patients treated with ADV for one year were selected for studying genotype shift by both deep sequencing and Sanger sequencing method.

Results

Sanger sequencing method found that 7.9% patients showed mixed genotype before ADV therapy. In contrast, all 38 patients showed mixed genotype before ADV treatment by deep sequencing. 95.5% mixed genotype rate was also obtained from additional 200 treatment-naïve CHB patients. Of the 13 patients with genotype shift, the fraction of the minor genotype in 5 patients (38%) increased gradually during the course of ADV treatment. Furthermore, responses to ADV and HBeAg seroconversion were associated with the high rate of genotype shift, suggesting drug and immune pressure may be key factors to induce genotype shift. Interestingly, patients with genotype C had a significantly higher rate of genotype shift than genotype B. In genotype shift group, ADV treatment induced a marked enhancement of genotype B ratio accompanied by a reduction of genotype C ratio, suggesting genotype C may be more sensitive to ADV than genotype B. Moreover, patients with dominant genotype C may have a better therapeutic effect. Finally, genotype shifts was correlated with clinical improvement in terms of ALT.

Conclusions

Our findings provided a rational explanation for genotype shift among ADV-treated CHB patients. The genotype and genotype shift might be associated with antiviral efficiency.

Infantile hepatitis B in immunized children: risk for fulminant hepatitis and long-term outcomes

BACKGROUND

Infantile hepatitis B after neonatal immunoprophylaxis is a rare yet distinct disease. This study aimed to analyze the long-term outcomes and risk factors in immunized infants with hepatitis B.

METHODS

The clinical parameters and outcomes of 41 infants born after universal immunization, and admitted for HBV-positive hepatitis were studied. All patients were followed for at least 6 months (median  = 4.4 years, range 0.6-18.1 years). Patient survival, changes of HBsAg and HBeAg status, and complications were analyzed.

RESULTS

Among the 41 cases (32 males, 9 females), 21 presented with fulminant hepatitis (FH), and 20 with non-fulminant hepatitis (NFH). Ninety-five percent (36/38) of the mothers were positive for hepatitis B surface antigen (HBsAg). Multivariate analyses revealed younger age of onset (age <7 months) and negative maternal hepatitis B e antigen (HBeAg) were associated with FH (p = 0.03 and p = 0.01, respectively). An infantile fulminant hepatitis B risk score using maternal/infant HBeAg positivity and onset age was proposed. Among the FH cases, the rate of mortality, HBsAg clearance, and chronic HBV infection were 47.6%, 38.1%, and 14.3%, respectively. Among the NFH cases, 35% developed chronic infection. Of the 9 chronically infected children received long-term follow-up, 8 had HBeAg seroconversion before 4 years of age. One case of FH developed hepatocellular carcinoma 14 years later.

CONCLUSIONS

Maternal HBsAg + /HBeAg- and early onset age were risk factors for FH in immunized infants. A significant portion of patients with FH or NFH evolve to chronic HBV infection, with HBeAg seroconversion in young childhood. Close surveillance for hepatocellular carcinoma is warranted in patients surviving infantile hepatitis B.

Hepatitis B vaccine alone or with hepatitis B immunoglobulin in neonates of HBsAg+/HBeAg- mothers: a systematic review and meta-analysis

OBJECTIVES

The cost-effectiveness of augmenting immunization against hepatitis B infection with hepatitis B immunoglobulin (HBIG) remains controversial, particularly for the subpopulation of babies of HBsAg+/HBeAg- mothers that are considered as low-infective. We aimed to evaluate the effectiveness of vaccine alone compared with vaccine plus HBIG for the immunization of babies of HBsAg+/HBeAg- mothers.

METHODS

We searched PubMed, Scopus and Cochrane Central Register of Controlled Trials databases to identify studies comparing the effectiveness of combined immunization (vaccine plus HBIG) with vaccine alone in neonates of HBsAg+/HBeAg- mothers. A systematic review and meta-analysis of eligible studies was performed.

RESULTS

A total of nine eligible studies were identified (four randomized controlled trials). No difference was found regarding the primary outcome of our meta-analysis, namely occurrence of hepatitis B infection, between neonates who received vaccine only, compared with those who received both vaccine and HBIG (four studies, 3426 patients, OR=0.82, 95% CI=0.41-1.64). This finding was consistent with regards to seroprotection rate (four studies, 1323 patients, OR=1.24, 95% CI=0.97-1.58). Safety data were not reported in the included studies.

CONCLUSIONS

The available limited published evidence suggests that vaccine alone seems to be equally effective to the combination of HBIG and hepatitis B vaccine for neonates of HBsAg+/HBeAg- mothers in preventing infection. Further studies are needed in order to clarify the potential benefit of combined immunization to this specific subgroup of patients.

Correlation between the promoter basal core and precore mutations and HBsAg quantification in French blood donors infected with hepatitis B virus

Hepatitis B virus (HBV) basal core promoter (BCP) and precore (PC) mutations, HBV viral load and HBV surface antigen (HBsAg) quantitation were screened to assess correlations between these HBV markers in asymptomatic chronic hepatitis B carriers in France. From January 2006 to July 2007, 200 sera were collected from patients who were discovered to be HBsAg-positive when they volunteered to give blood. Direct sequencing of precore/core gene was used to detect A1762T/G1764A mutations in the BCP and G1896A in the PC region. HBV viral load and HBsAg were quantified with two commercials assays. The prevalence of the BCP and PC mixed/mutants were 37% and 60% respectively (P = 0.0001). HBV DNA level and HBsAg titer were significantly lower in subjects harboring the mixed/mutant PC virus compared to those infected by the wild phenotype. No significant difference was observed in HBV viral loads of blood donors infected by wild or mixed/mutant BCP viruses. Mutant or mixed PC virus was associated with male gender, HBeAb-positive status and HBV/D and HBV/E genotypes. BCP mutations were associated with age, and both HBV/A-HBV/E genotypes.The genetic properties of HBV in this cohort showed that most of the blood donors had a negative HBeAg serological status and harbored the PC mutant phenotype in combination with low levels of both HBV DNA and HBsAg. As the study was conducted in healthy subjects who could be considered as asmptomatic carriers, these results suggest a possible protective effect of the G1896A mutation against severe liver lesions.

Occult hepatitis B infection in the immigrant population of Sicily, Italy

In Italy, about 7 % of the resident population is represented by immigrants originating from geographic regions at high endemicity for hepatitis B virus infection. This study aims to assess the prevalence of occult HBV infection (OBI) including the identification of HBV-genotypes in a population of immigrants serologically negative for hepatitis B surface antigen (HBsAg). Between May 2006 and May 2010, 339 immigrants were tested for markers of HBV, hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections. HBV-DNA was tested by using nested-PCR assays on three different genetic region. HBV-DNA was detected in plasma samples of 11/339 (3.2 %) patients. Most of them had no serological markers of HBV infection, 3/58 (5.2 %) were anti-HBc-alone, and 4/13 (30.8 %) were anti-HIV positive. HIV positivity was the only factor independently associated with the higher probability of observing OBI (OR = 16.5, p < 0.001). No HCV co-infected patients were found. Genotype D was detected in 9/11 (81.8 %) OBI cases, while the remaining two (18.2 %) were classified as genotype E. Although OBI was found at lower rate than expected among immigrants from highly endemic countries, anti-HBc alone positivity was confirmed as a sentinel marker of occult HBV infection. Nevertheless, a marked heterogeneity of HBV markers was found among HBV-DNA positive subjects. Our finding evidenced the predominance of HBV-genotype D viral strains among OBI cases, also in those from geographical areas where overt HBV infections are mainly sustained by viral genotypes other than D.

High endemicity and low molecular diversity of hepatitis B virus infections in pregnant women in a rural district of North Cameroon

Background

A program, supported by the GEMHEP (Groupe d'étude Moléculaire des Hépatites), was established in 2007 in the sanitary district of Tokombéré, to prevent perinatal transmission of hepatitis B virus (HBV). It comprises screening for HBV surface antigen (HBsAg) in all pregnant women and vaccinating the newborn if tests are positive.

Methods/Principal Findings

1276 women were enrolled in the study after providing informed consent. Demographic data and blood samples were available for 1267 of the enrolled patients. HBsAg was determined locally using a rapid test (Vikia HBsAg, Biomerieux). Tests for HBV and HDV virological markers (HBeAg, anti-HDV antibodies (Ab), HBV-DNA, HDV-RNA, HBV and HDV genotypes) were performed on the confirmed HBsAg-positive samples in the virology unit of the Angers University Hospital (France). HBsAg was found in 259 of the 1267 pregnant women (20.4%) between January 2009 and April 2010, of whom 59 were HBeAg-positive (22.7%) with high levels of HBV-DNA. Anti-HDV Ab were found in 19 (7.3%) of the HBsAg-positive women. The prevalence rates of HBsAg and HDV were not age-dependent whereas HBeAg carriers were statistically younger than non carriers. Basal core promoter (BCP) and precore (PC) mutations and genotypes were determined by sequencing. Of 120 amplified sequences, 119 belonged to HBV genotype E (HBV/E) and the 9 HDV strains belonged to HDV clade 1. In the PC region, 83/228 patients (36.4%) harbored a G1896A mutant or mixed phenotype virus. In the BCP region, the double mutation A1762T/G1764A and the G1757A substitution were detected respectively in 26/228 patients (11.4%) and 189/228 patients (82.8%).

Conclusions

Our results confirm the high prevalence and low molecular diversity of HBV in Far Northern Cameroon; more than 20% of the infected women were highly viremic, suggesting a high rate of HBV perinatal transmission and supporting the WHO recommendation to vaccinate at birth against hepatitis B.

Distinct quasispecies characteristics and positive selection within precore/core gene in hepatitis B virus HBV associated acute-on-chronic liver failure

BACKGROUND AND AIM

The cause of hepatitis B virus associated acute-on-chronic liver failure (ACLF) remains unclear. Quasispecies can contribute to virus persistence and pathogenesis. We used a bioinformatics-based molecular evolution approach to compare quasispecies characteristics and positive selection sites within HBV precore/core gene between ACLF and chronic hepatitis B (CHB) patients.

METHODS

HBV precore/core gene were amplified from 11 ACLF and 10 CHB patients harboring HBV genotype B; following DNA cloning and sequencing quasispecies complexity, diversity, and positive selection sites within the precore/core gene were determined by bioinformatics analysis, and compared between the patient groups.

RESULTS

Both quasispecies complexity (P=0.022 at nucleotide level and 0.008 at amino acid level) and diversity (P<0.05) were found to be significantly greater in ACLF than in CHB. The frequency of G1896/A mutation in ACLF (175/298 clones, 58.7%) was also significantly higher than in CHB (100/230 clones, 43.5%) (P=0.0005). Moreover, analysis of positive selection revealed that significantly more patients with such sites were present in ACLF than in CHB (8/11 VS 2/10, P=0.03); the majority of these positive selection sites lay within HLA-restricted epitopes.

CONCLUSIONS

The ACLF patients showed distinct quasispecies characteristics with higher complexity and diversity within the HBV precore/core gene. The increased HBV quasispecies complexity and diversity, together with a distinct set of positive selection sites, is likely associated with the development of ACLF.

Predominance of precore mutations and clinical significance of basal core promoter mutations in chronic hepatitis B virus infection in Indonesia

Chronic hepatitis B virus (HBV) infection is a major health problem worldwide, with a particularly high prevalence in the Asian-Pacific region. During chronic hepatitis B virus (HBV) infection, mutations commonly occur in the basal core promoter (BCP) and precore (PC) regions of HBV, affecting HBeAg expression, particularly following HBeAg serocon-version. Mutations in the B- and T-cell epitopes of the HBV core have also been observed during disease progression. The clinical significance of HBV genome variability has been demonstrated, however the results are a subject of controversy. Considering the characteristics of the virus associated with geographical location, the profiles of BCP, PC and core mutations and their clinical implications in patients with chronic HBV infection in Surabaya, Indonesia, were investigated. The BCP, PC and core mutations and HBV genotypes were detected by direct sequencing. The HBeAg/anti-HBe status and HBV DNA levels were also assessed. This study enrolled 10 patients with chronic HBV infection (UC) from Dr Soetomo General Hospital and Indonesian Red Cross, Surabaya, East Java, Indonesia, 10 patients with chronic hepatitis B and liver cirrhosis (LC) and 4 patients with chronic hepatitis B and hepatocellular carcinoma (HCC) from Dr Soetomo General Hospital. The PC mutation A1896 was predominant in all the groups (60-100%), together with the PC variant T1858, which was associated with HBV genotype B. The number of detected core mutations (Thr/Ser130) was higher in HCC patients (50%). However, the BCP mutations T1762/A1764 were predominant in LC patients (50-60%). The LC and HCC patients carried HBV isolates with additional mutations, at least at BCP or PC, mainly following HBeAg seroconversion. In the majority of anti-HBe-positive samples, the BCP T1762/A1764 mutations were associated with a high viral load, regardless of the PC 1896 status. In conclusion, the PC mutations were found to be predominant in all the groups. However, the BCP mutations were mainly detected in the LC group and may be considered as a critical indicator of a poor clinical outcome.

Hepatitis B virus genetic variants: biological properties and clinical implications

Hepatitis B virus (HBV) causes a chronic infection in 350 million people worldwide and greatly increases the risk of liver cirrhosis and hepatocellular carcinoma. The majority of chronic HBV carriers live in Asia. HBV can be divided into eight genotypes with unique geographic distributions. Mutations accumulate during chronic infection or in response to external pressure. Because HBV is an RNA-DNA virus the emergence of drug resistance and vaccine escape mutants has become an important clinical and public health concern. Here, we provide an overview of the molecular biology of the HBV life cycle and an evaluation of the changing role of hepatitis B e antigen (HBeAg) at different stages of infection. The impact of viral genotypes and mutations/deletions in the precore, core promoter, preS, and S gene on the establishment of chronic infection, development of fulminant hepatitis and liver cancer is discussed. Because HBV is prone to mutations, the biological properties of drug-resistant and vaccine escape mutants are also explored.

Molecular analysis of hepatitis B virus associated with vaccine failure in infants and mothers: a case-control study in Thailand

Perinatal transmission of hepatitis B virus (HBV) has been controlled incompletely despite adequate immunoprophylaxis in infants. The aim of this study was to characterize virological factors of HBV associated with vaccine failure in Thailand. Sera of 14 infected infants (13 HBeAg-positive and one HBeAg-negative) with vaccine failure and their respective mothers (group M1) were tested quantitatively for HBV DNA by real-time PCR, HBV genotypes and mutations were characterized by direct sequencing. Sera collected from 15 HBeAg-positive (group M2) and 15 HBeAg-negative (group M3) mothers whose infants had been vaccinated successfully served as controls. The results showed that group M1 and group M2 mothers had equal titers of HBV DNA but higher titers than group M3. All infected infants and their respective mothers had the same HBeAg status and HBV genotypes. DNA analysis in a pair of HBeAg-negative infant and mother revealed that both were infected with an HBV precore mutant (G1896A). Escape mutants in the "a" determinant region (residues 144 and 145) were detected in two (14%) infected infants. The prevalence of BCP mutations/deletions in groups M2 and M3 was higher significantly than in group M1 (P = 0.022 and P < 0.001, respectively). In conclusion, instead of the HBeAg status, a high titer of HBV DNA in mothers was the major contributor to perinatal transmission of HBV. Escape mutants might be associated with vaccine failure in some infants. BCP mutations/deletions in mothers might contribute to the prevention of mother-to-infant transmission of HBV.

Fatal fulminant primary hepatitis B virus infections with G1896A precore viral mutants in southeastern France

Fulminant hepatitis has been shown to occur in about 1% of acute hepatitis B virus (HBV) infections, and its mortality rate is nearly 70%. Specific HBV genotypic features have been pointed out in fulminant acute hepatitis B worldwide, but these associations remain controversial. We describe all four primary HBV infections diagnosed in 2008 in our institution in Marseille, southeastern France, including two fatal cases. HBV genotypes were D or E. Precore G1896A HBV mutants were detected in both fatal fulminant primary HBV infections. Hepatitis B surface antigen and hepatitis B e antigen (HBeAg) were negative in two and three cases, respectively, despite HBV DNA detection. Primary HBV infection remains a cause of death in France. The impact of the precore G1896A mutation on the severity of AHB deserves to be assessed in larger studies in this country.

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.

Quantification of complex precore mutations of hepatitis B virus by SimpleProbe real time PCR and dual melting analysis

BACKGROUND

Hepatitis B virus (HBV) precore G1896A mutation is associated with Hepatitis B e antigen (HBeAg) seroconversion. This mutation and the adjacent G1899A mutation also appear to associate with increased risk of hepatocellular carcinoma. Quantitative mutant dynamics may help determine the potential of these mutants as clinical biomarkers. However, a reliable method to quantify either mutant is not available, partly because the viral genome has polymorphisms in general and the precore mutations are complex.

OBJECTIVES

(1) To develop a reliable and ultrasensitive assay for the quantification of HBV G1896A and/or G1899A mutants. (2) To obtain preliminary data on the quantities of the precore mutants in patients.

STUDY DESIGN

A SimpleProbe real time PCR assay was developed to quantify the HBV precore mutants. Dual melting analysis and a primer-probe partial overlap approach were used to increase detection accuracy. A wild-type selective PCR blocker was also developed to increase mutant detection sensitivity.

RESULTS

The assay correctly identified the precore sequence from all 62 patient samples analyzed. More than 97% of precore sequences in the GenBank can be recognized. Mutant detection sensitivity reached 0.001% using a wild type-selective PCR blocker. At least one precore mutant can be detected from all 20 HBeAg-positive individuals who were negative for precore mutations by DNA sequencing.

CONCLUSIONS

The reliability of this ultrasensitive mutation quantification assay was demonstrated. The same approaches may be useful for the detection of other clinically significant mutations. Evolution of the precore mutants warrants further studies.

The underlying mechanisms for the "simultaneous HBsAg and anti-HBs serological profile"

The course of HBV infection is determined by the interplay between viral replication via HBV protein production and the host's immune response. Therefore, the diagnosis of infection in clinical practice is established by the serological detection of HBV protein products as well as antibodies produced by the host. Although the serological findings for assessing the clinical course of infection are already well established, the expression of viral proteins and the dynamics of antibody production may vary during the natural course of infection. This causes the HBV infection to be occasionally associated with the presence of unusual serologic profiles, which can lead to doubts in the interpretation of results and mistaken serological diagnosis. The simultaneous detection of HBsAg and anti-HBs in the blood stream comprises an atypical serological profile, somewhat incoherent, whose significance can be complicated to establish. Outlined in this article are some immunological and molecular mechanisms which could justify the existence of this profile in which there is a great laboratorial and clinical interest.

Precore and core promoter mutations of the hepatitis B virus gene in chronic genotype C-infected children

The precore (G1896A) and core promoter (A1762T, G1764A) mutations of the hepatitis B virus gene are known to be associated with changes in immunologic phase or the progression to complicated liver disease in adults. We analyzed these mutations in chronically HBV-infected children. Serum was collected from 37 children with chronic HBV infection from March 2005 to September 2008. HBV DNA extraction and nested PCR were followed by sequencing of the PCR products. The children were 6.7 ± 4.6 yr old. All of 37 children had HBV genotype C. Of the cohort, 31 (83.8%) were HBeAg-positive and 6 (16.2%) were HBeAg-negative; the former group comprised 18 (48.6%) who were in the immune-tolerance phase (ITP) and 13 (35.2%) in the immune-clearance phase (ICP). Most of the patients had HBV DNA levels of > 1.0 × 10(8) copies/mL. In the ITP group, only 1 (5.5%) had core promoter mutations, and none had the precore mutation. In the ICP group, only 2 (15.4%) had core promoter mutations; the remaining 6 patients had HBV DNA levels of < 2.0 × 10(3) copies/mL and no core promoter/precore mutations. The very low incidence of the precore/core promoter gene mutation, in children, suggests that these mutations may be the result of life-long chronic HBV infection.

Association of hepatitis B virus mutations in basal core promoter and precore regions with severity of liver disease: an investigation of 793 Chinese patients with mild and severe chronic hepatitis B and acute-on-chronic liver failure

OBJECTIVE

To investigate the features of hepatitis B virus (HBV) basal core promoter/precore (BCP/PC) mutations and genotypes in a large number of mild/severe chronic hepatitis B (CHB-M/CHB-S), and acute-on-chronic liver failure (ACLF) patients and analyze the clinical implications of the virologic features.

PATIENTS AND METHODS

Sera of 793 (325 CHB-M, 170 CHB-S, and 298 ACLF) patients admitted to or who had visited Beijing 302 Hospital from January 2005 to December 2008 were collected and successfully amplified for the HBV BCP/PC and a 1225-bp-long S/Pol (nt 54-1278) gene regions. Biochemical and serological parameters and HBV DNA level were routinely performed. Viral DNA was extracted and subjected to a nested PCR. Genotypes/subgenotypes were determined based on complete genomic sequence or on analysis of the 1225-bp-long S/Pol-gene sequence. HBV genotyping was performed by direct PCR sequencing followed by molecular evolutionary analysis of the viral sequences. A P value of <0.05 (two-sided) was considered to be statistically significant.

CONCLUSIONS

Our findings suggest that CHB patients infected with BCP/PC mutant viruses are more susceptible to severe hepatitis and ACLF than those with the BCP/PC wild-type virus and that ACLF patients with PC mutant viruses have an increased risk of death. As such, the HBV PC mutation is a potential predictive indicator of ACLF outcome.

Hepatitis B virus genotype and basal core promoter/precore mutations are associated with hepatitis B-related acute-on-chronic liver failure without pre-existing liver cirrhosis

The study was undertaken to investigate the features and clinical implications of hepatitis B virus (HBV) genotypes, basal core promoter (BCP) and precore (PC) mutations in hepatitis B-related acute-on-chronic liver failure (HB-ACLF). Samples from 75 patients with HB-ACLF and without pre-existing liver cirrhosis and 328 age-matched patients with chronic hepatitis B (CHB) were analyzed. HBV genotype and BCP/PC mutations were determined by direct sequencing. Mutations at 8 sites of the BCP/PC region were compared between the two groups of patients. A significantly higher ratio of genotype B to C was found in patients with HB-ACLF than in patients with CHB (30.7-69.3% vs 16.5-82.6%, P < 0.01). Single mutations including T1753V (C/A/G), A1762T, G1764A, G1896A and G1899A and triple mutations T1753V/A1762T/G1764A and A1762T/G1764A/C1766T (or T1768A) were more frequently detected in patients with HB-ACLF than in patients with CHB. Correspondingly, BCP/PC wild-type sequences were absent in patients with HB-ACLF in contrast to 27.1% in patients with CHB. The BCP/PC mutations were found to be associated with increased HBeAg negativity, higher alanine aminotransferase level and lower viral load. Patients with HB-ACLF infected with the PC mutant virus had a higher mortality. The findings suggest that patients with CHB infected with genotype B with BCP/PC mutations were more likely to develop HB-ACLF than those with genotype C with wild-type BCP/PC regions, and patients with HB-ACLF with the PC mutation had increased risk of a fatal outcome.

[Results of a novel real-time PCR, sequence analysis, Inno-LiPA line probe assays in the detection of hepatitis B virus G1896A precore mutation in French blood donors]

AIM

To screen hepatitis B virus (HBV) genotypes and associated basal core promoter (BCP; T1762A/A1764) and precore (PC; A1896) mutations among the 100 HBV surface antigen (HBsAg) positive voluntary blood donors in France.

METHODS

HBV genotypes were determined by using direct sequence analysis. Three methods were used to detect G1896A mutation: non-commercial real-time PCR (PCRTR°, line probe assay (InnoLiPA HBV PreCore, INNOGENETICS(®)) and direct sequencing of precore gene. HBV viral load was quantified with two commercial real-time PCR (COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HBV Test/Roche and Real Time HBV/M2000/Abbott).

RESULTS

The mean age of donors was 30 (18-64). Patients were from Africa (42%), Europa (50%), and Asia (8%). HBV/D was the most predominant (37%) genotype followed by HBV/A (31%) and HBV/E (22%). PC and BCP mutants were found in 57% with Inno-LIPA HBV test and 59% with both PCRTR and sequencing methods. A significant difference in the viral load of blood donors with wild and PC mutants was observed with the Taqman Cobas real time PCR (3,19 Log(10) UI/ml versus 4,93 Log(10) UI/ml, p < 0.05). Precore phenotype determination was in agreement with the three PC mutation detection methods in 56% of cases.

CONCLUSIONS

Non-Caucasian genotype E was present in the French blood donors. PC mutation was more common than BCP mutations in this study. As HBV infected blood donors were more often asymptomatic carriers, we could speculate that the G1896A mutation may favour the asymptomatic state, supporting previous observations.

Features and clinical implications of hepatitis B virus genotypes and mutations in basal core promoter/precore region in 507 Chinese patients with acute and chronic hepatitis B

BACKGROUND

The association of hepatitis B virus (HBV) genotypes and basal core promoter (BCP) and precore (PC) mutations with the clinical characteristics is increasingly recognized.

OBJECTIVE

To investigate virologic features and clinical implications of HBV genotypes, BCP and PC mutations between large-size patients with acute hepatitis B (AHB) and chronic hepatitis B (CHB).

STUDY DESIGN

One hundred and eighty-two AHB patients and 325 CHB patients were investigated. HBV genotypes and BCP/PC mutations were determined by direct sequencing. Mutations at 10 interested sites of the BCP/PC region were compared between the two groups of patients.

RESULTS

AHB patients had a significantly higher ratio of genotype B to C than CHB patients (37.4-62.6% vs. 16.6-83.4%, P<0.001). The prevalence of BCP/PC wild-type virus was 60.4% in AHB patients in contrast to 28.9% in CHB patients. Significantly lower prevalence of A1762T, G1764A, G1896A, and G1899A but higher prevalence of T1758C was found in AHB patients. Interestingly, T1758C and A1762T/G1764A appeared mutual restraint. Genotype B virus had lower BCP mutation frequency and similar PC mutation frequency compared to genotype C virus. AHB patients with BCP/PC mutant virus had higher viral load, whereas CHB patients with BCP/PC mutant virus had lower viral load and elevated alanine aminotransferase, in comparison with those with the wild-type virus.

CONCLUSION

Patients with genotype B virus, BCP/PC wild-type virus or T1758C mutant virus were more susceptible to develop AHB, whereas high prevalence of the BCP/PC mutations was associated with CHB development.

Prediction of response to treatment of chronic hepatitis B with pegylated interferon in the Philippines

The response marker for interferon has not been investigated fully for hepatitis B viruses (HBVs) in the Philippines where novel subtypes B5 and C5 were recognized recently. The prediction parameters for interferon treatment were assessed, with emphasis on the mutation patterns in the basal core promoter and precore regions in patients with chronic hepatitis B. Seventeen HBeAg-positive patients were stratified according to response to treatment with pegylated interferon based on HBe seroconversion and HBV load. Intra-patient distributions of wild-type strains (A1762, G1764) and variants (T1762, A1764) were analyzed using HBV-DNA amplification and subsequent molecular cloning. The rate of variants (T1762, A1764) harbored by a patient was higher among responders (41.2% and 31% per person on average) than among non-responders (2.4% and 2.4%) to treatment with pegylated interferon at the baseline, respectively (P < 0.05). The rate of variants (T1762, A1764) harbored by responders (41.2% and 31%) decreased to 1.7% and 1.7%, and wild-type strains (A1762, G1764) conversely became majority (98.3% and 98.3%) after treatment with pegylated interferon, respectively. HBV strains harbored by two of six responders and a patient with lower baseline load (1.0 x 10(4) copies/ml) showed genotype shift from A to other genotypes, where genotype A disappeared preferentially after the loss of HBeAg and genotypes B and C formed a major population. These results suggest that the HBV variants (T1762, A1764) and HBV genotype A in the Philippines have an advantage in the response to pegylated interferon. These results warrant a large-scale examination for further precise prediction of the response to treatment with interferon.

[Hepatitis B virus genetic diversity and mutant]

Hepatitis B virus (HBV) is a partially double stranded DNA virus with genetic diversity represented by eight genotypes (A to H). Natural course and response to treatment could be affected by HBV genotypes. HBV shows high rates of turn over in the absence of proof-reading ability. As a result, large amounts of quasispecies are produced naturally or antiviral-associated. HBV consists of four open reading frames, namely preS/S gene, precore/core gene, polymerase gene, and X gene. Mutations on preS gene can result in undetectable HBsAg even in case that HBV is replicating. Surface gene mutation leads to decreased binding affinity to anti-HBs, which is associated with a vaccine escape mutant. Precore mutation abolishes HBeAg whereas mutations on basal core promoter gene down-regulate the HBeAg production. Mutations on basal core promoter are associated with increased HBV replication and high incidence of progressive liver diseases such as liver cirrhosis and hepatocellular carcinoma. Mutations on polymerase genes are often induced by antiviral therapy. Emergence of antiviral-resistant mutation is the major cause of treatment failure. Furthermore, existence of prior antiviral-resistant mutations limits the options of subsequent antiviral agents. Therefore, judicious use of antivirals and selection of the most potent drug with the lowest resistance rate are of the utmost importance for the prevention of antiviral-associated mutants. Detailed knowledge and understanding of HBV genetic diversity and mutant would be critical to establish strategies for the diagnosis and management of HBV infection.

Biological features of hepatitis B virus isolates from patients based on full-length genomic analysis

The mechanisms for HBV persistence and the pathogenesis of chronic HB have been shown mainly due to defects in host immune responses. However, HBV isolates with different biological features may also contribute to different clinical outcomes and epidemiological implications in viral hepatitis B (HB). This review presents interesting biological features of HBV isolates based on the structural and functional analysis of full-length HBV isolates from various patients. Among isolates from children after failure of HB vaccination, 129L mutant at the 'a' determinant was found with normal binding efficiency to anti-HBs, but with reduced immunogenicity, which could initiate persistent HBV infections. Isolates from fulminant hepatitis (FH) B patients were not all highly replicative, but differences in capacities of anti-HBs induction could be involved in the pathogenesis of FH. The high replicative competency of isolates from hepatocellular carcinoma (HCC) patients could result in enhanced immune-mediated cytopathic effects against HBV viral proteins, and increased transactivating activity by the X protein. The mechanism of a double-spliced variant in enhancing replication of the wild-type virus is presented. The importance of integrating structural and functional analysis to reveal biological features of HBV isolates in viral pathogenesis is discussed.

Hepatitis B virus infection

Since the introduction of the hepatitis B vaccine and other preventive measures, the worldwide prevalence of hepatitis B infection has fallen. However, chronic infection remains a challenging global health problem, with more than 350 million people chronically infected and at risk of hepatic decompensation, cirrhosis, and hepatocellular carcinoma. An improved understanding of hepatitis B virology, immunology, and the natural course of chronic infection, has identified hepatitis B virus replication as the key driver of immune-mediated liver injury and disease progression. The approval of potent oral antiviral agents has revolutionised hepatitis B treatment since 1998. Conventional and pegylated interferon alfa and nucleoside and nucleotide analogues are widely authorised treatments, and monotherapy with these drugs greatly suppresses virus replication, reduces hepatitis activity, and halts disease progression. However, hepatitis B virus is rarely eliminated, and drug resistance is a major drawback during long term therapy. The development of new drugs and strategies is needed to improve treatment outcomes.

Characterization of genotype-specific carboxyl-terminal cleavage sites of hepatitis B virus e antigen precursor and identification of furin as the candidate enzyme

Hepatitis B e antigen (HBeAg) is a secreted version of hepatitis B virus (HBV) core protein that promotes immune tolerance and persistent infection. It is derived from a translation product of the precore/core gene by two proteolytic cleavage events: removal of the amino-terminal signal peptide and removal of the carboxyl-terminal arginine-rich sequence. Four RXXR motifs are present at the carboxyl terminus of the HBeAg precursor, with the first two fused as (151)RRGRSPR(157). Genotype A possesses two extra amino acids at the first motif ((151)RRDRGRSPR(159)), which weakens the first motif and separates it from the second one. Western blot analysis of patient sera revealed a single HBeAg form for genotypes B to D but two additional forms of larger sizes for genotype A. Site-directed mutagenesis and transfection experiments with human hepatoma cell lines indicated that HBeAg of genotype B is derived from cleavage at the first ((151)RRGR(154)) motif. The major HBeAg form of genotype A corresponds to cleavage at the second ((156)RSPR(159)) motif, and the other two forms are cleavage products of the first ((151)RRDR(154)) and third ((166)RRRR(169)) motifs, respectively. Only the cleavage product of the third motif of genotype A was observed in furin-deficient LoVo cells, and an inhibitor of furin-like proprotein convertases blocked cleavage of the first and second motifs in human hepatoma cells. In conclusion, our study reveals genotypic differences in HBeAg processing and implicates furin as the major enzyme involved in the cleavage of the first and second RXXR motifs.

Effect of basal core promoter and pre-core mutations on hepatitis B virus replication

There are two hypotheses explaining a fulminant outcome after hepatitis B virus (HBV) infection, both of which may be applicable at the same time: (i) basal core promoter (BCP) mutations increase viral replication, allowing rapid spread of the virus through the liver, and (ii) pre-core (pre-C) mutations abrogating hepatitis B e antigen (HBeAg) synthesis remove its tolerogenic effect, leading to a vigorous immune response. This study investigated the effect of these mutations on virus replication efficiency and HBeAg production. Substitutions A1762T/G1764A and T1753C, C1766T and T1768A in the BCP region, and G1896A and G1899A in the pre-C region, were examined either alone or in combination, using a common genetic background. Huh7 cells were transfected with these constructs and real-time PCR was used to quantify released virion-associated and intracellular HBV DNA, pregenomic RNA and pre-C mRNA. In addition, culture supernatants were tested for hepatitis B surface antigen (HBsAg) and HBeAg. The double BCP mutation (A1762T/G1764A) and the pre-C mutations (G1896A, G1899A), either alone or in combination, had no appreciable effect on the replication capacity of the virus. In contrast, clones with mutations at positions 1766/1768, 1762/1764/1766 and 1753/1762/1764 exhibited increased-replication phenotypes. HBeAg was undetectable in all cultures transfected with constructs bearing the G1896A stop-codon mutation, as expected. In contrast, constructs with additional mutations in the BCP region had appreciably lower levels of HBeAg expression than the wild type. Thus, core promoter mutations other than those at 1762/1764 appear to upregulate viral DNA replication and, at the same time, greatly reduce HBeAg production.

Analysis of the entire nucleotide sequence of hepatitis B causing consecutive cases of fatal fulminant hepatitis in Miyagi Prefecture Japan

We encountered five consecutive patients with fulminant hepatitis induced by acute hepatitis B virus (HBV) infection in 2000--2001 in Japan. They had not had previous contact each other, and were referred to us from different hospitals. Although a 69-year-old woman could be rescued by intensive internal treatment, the four patients died. We analyzed the partial (nt 278-646) and entire nucleotide sequences of the HBV obtained from them, and their divergences were 0-0.3% and 0-0.2%, respectively. The results suggested that they had been infected with the same HBV isolates. The isolates belonged to genotype B and subgenotype B2 on the phylogenetic tree analysis (AB302942-AB302946). As for the nucleotides sequences of them, previously reported mutations of G1896A, A1762T, and G1764A were present. Amino acid analysis revealed that previously reported Ile97Leu and Pro130Non-Pro in the core region and Trp28Stop in the precore region were present. As for the entire nucleotide sequences among B2, AB302942 showed low divergences with AF121245 and AB073834 (1.7%), and X97850 from patients with fulminant hepatitis (3.2%). We compared the two consensus nucleotides derived from AB302942 and X97850 (fulminant hepatitis) versus AY121245 and AB073834 (non-fulminant hepatitis), which revealed a difference in nt 1,504 located in the P and X region. Nucleotide 1,504 was C for isolates from fulminant hepatitis and G for non-fulminant hepatitis, and it was recognized among most of the isolates belonging to B2 registered on GenBank. Further studies could disclose the mechanism of severe inflammation of liver that finally leads to fulminant hepatitis.