Longitudinal study on mutation profiles of core promoter and precore regions of the hepatitis B virus genome in children

Updates in the management of hepatitis B in children

Introduction: Universal infant hepatitis B virus (HBV) vaccination program has reduced HBV infection dramatically in vaccinated young generations. Management of chronically infected children is still challenging concerning high viral load with mostly mild diseases, yet with a nonnegligible proportion of advanced diseases, and long-term effect of antivirals. However, with more potent antivirals approved for pediatric patients, to start antivirals earlier in eligible patients may benefit their outcomes. This review aimed to update the current management of chronic hepatitis B in children.Areas covered: This review covered the natural history of chronic HBV infection, management of chronic hepatitis B in children from the past to the present, current consensus on the treatment of chronic hepatitis B in children, controversies in cessation of oral antivirals, and management of special populations such as pregnancy and co-infections.Expert opinions: Without contraindication, peginterferon is recommended for immune-active children ≥ 3 years old. For those intolerant, decompensating or preferring oral therapy, first-line Nucleos(t)ide analogs (NUC), Entecavir or Tenofovir, may be applied. For immune-tolerant or inactive carriers, close monitoring is crucial. When to stop NUCs and novel therapies for HBV cure await further research.

Genotypes and Hot Spot Mutations of Hepatitis B Virus in Northwest Chinese Population and Its Correlation with Diseases Progression

Hepatitis B virus (HBV) infection is a critical incentive for chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). Different genotypes and genome mutations of HBV have been found to be related to the progression of these liver diseases. However, their clinical significance is still under debate. The objective of this study was to determine the association of HBV genotypes and hot spot mutations in the reverse transcriptase (RT) and basal core promoter-precore (BCP-PreC) region with HBV-infected diseases in a northwest Chinese population. HBV genotyping and DNA sequencing were performed in samples of 980 patients. Appropriate statistical methods were adopted to assess HBV genetic features and its clinical association. It was found that the prevalent HBV genotype in northwestern Chinese patients was HBV/C (61.33%), followed by HBV/B (36.63%). In RT region, in addition to the reported nucleoside analogue- (NA-) resistance missense mutations, new silent mutations at rt169 and rt180 were found to raise the risk of HCC in patients with HBV/C. And the heterozygous mutation status of rt169/rt180 was associated with the increased risk of both HCC and NA resistance (OR > 1, P < 0.01) regardless of HBV genotypes. In BCP-PreC region, multiple mutations and combinations, especially at nt 1762/1764 and nt 1896/1899, were characterized to be the causes of spurious HBeAg negativity and liver function injury, as well as the risk factors for HCC progression (P < 0.01). Additionally, a novel mutation at nt1799G>C was likely found to increase the risk of HCC in patients with HBV/B. These findings revealed an association between HBV genotypes and HBV genetic mutations in RT and BCP-PreC region and progression of hepatitis B. It would be helpful for risk evaluation and diagnostic improvement based on these genetic features.

Viral Factors Affecting the Clinical Outcomes of Chronic Hepatitis B

Chronic hepatitis B (CHB) exhibits a variety of clinical outcomes, ranging from spontaneous resolution of hepatitis B to severe adverse consequences, including the development of cirrhosis, hepatic failure, and hepatocellular carcinoma. The heterogeneous clinical courses of chronic hepatitis B virus (HBV) infection reflect the complex host-virus interactions, and point to the difficulty and necessity of identifying the patients at risk. With the advance of HBV virology, several viral factors have been found to be associated with the long-term clinical outcomes of CHB patients. Different viral factors probe different aspects of CHB. Integration of these viral factors may help to determine the disease state of patients more accurately, and identify the patients who require timely antiviral therapy to prevent the development of detrimental clinical outcomes. In this article, we will introduce the conventional and emerging viral factors that are associated with clinical outcomes and discuss their utility in a clinical setting.

Natural history of chronic hepatitis B virus infection from infancy to adult life - the mechanism of inflammation triggering and long-term impacts

Chronic hepatitis B virus (HBV) infection in endemic areas usually starts since infancy and early childhood and persists lifelong. The clinical course varies among different chronic infected subjects. Majority of chronic HBV infected children present with immune-tolerant status initially, experience the immune clearance phase with various degree of liver injury during or beyond puberty, and then enter the inactive phase after hepatitis B e antigen (HBeAg) seroconversion. Part of them may have HBV DNA titers elevation with hepatitis flare after HBeAg seroconversion, the so call HBeAg-negative hepatitis flare. Liver cirrhosis, and even hepatocellular carcinoma may develop afterward.

The complex course of chronic HBV infection is associated with the age/route of viral acquisition, host factors such as immune and endocrine factors, viral factors, and host-viral interactions. The adrenarche and puberty onset modulate the start of immune clearance and the severity of liver inflammation in chronic HBV infected children. The genotype and phenotype of human cytokines, innate immunity, and human leukocyte antigens are also associated with the onset of immune clearance of HBV and severity of inflammation. Immune escape HBV mutant strains, emerged during the immune clearance phase under host immune surveillance, may cause different impacts on viral biosynthesis, host immune responses, and clinical course.

Early events in childhood during chronic HBV infection may serve as important predictors for the later outcome in adulthood. Understanding the mechanisms triggering liver inflammation and their long-term impacts may enhance the development of better and earlier therapeutic strategies for patients with chronic HBV infection.

The incidence rate over 10 years of naturally occurring, cancer related mutations in the basal core promoter of hepatitis B virus

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The annual incidence rate of the basal core promoter (BCP) double mutations is 3.8%.

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The incidence rate tends to decrease with age and the peak appeared early in the life.

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Nucleotide (nt) 1762 is the favoured site of the first mutation.

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Viruses with a single mutation at nt 1762 or 1764 are more prone to develop double mutations.

Cross-sectional analyses showed that the prevalence of basal core promoter (BCP) double mutations (nt 1762T, 1764A) of hepatitis B virus (HBV) gradually increases with age. We aimed to determine the incidence rate of the mutations over 10 years. Study subjects were selected from the Long An cohort established in 2004, including 59 with HBV with single mutations at nt 1762 or 1764 in the BCP and 342 with wild type BCP sequences at baseline. Their serum samples for analysis were obtained at the 3rd and 10th annual visits, respectively. The results showed that the annual incidence rate of BCP double mutations is 3.8% (95% confidence interval [CI]: 1.4–6.2) and tends to decrease with age. The peak incidence is in the 30–34 years age-group. The incidence rate in HBeAg positive individuals (5.5%) is significantly higher than in those without HBeAg (3.4%) (P < 0.05). The incidence rate is significantly higher in genotype C (4.8%) than in genotype B (2.8%) or I (3.1%). The incidence rate of the mutations (6.8%) developing from a single mutation at nt 1762 or 1764 is significantly higher than that (3.8%) from the wild type sequence (P < 0.005). The difference in incidence of single mutations between nt 1762 (0.7%) and 1764 (0.03%) is significant (P < 0.05). In conclusion, the incidence rate of BCP double mutations tends to decrease with age after the age of 35 years. Viruses with a single mutation at nt 1762 or 1764 are more prone to develop double mutations. Nt 1762 is the more common site of the first mutation.

Analysis of ultra-deep pyrosequencing and cloning based sequencing of the basic core promoter/precore/core region of hepatitis B virus using newly developed bioinformatics tools

Aims

The aims of this study were to develop bioinformatics tools to explore ultra-deep pyrosequencing (UDPS) data, to test these tools, and to use them to determine the optimum error threshold, and to compare results from UDPS and cloning based sequencing (CBS).

Methods

Four serum samples, infected with either genotype D or E, from HBeAg-positive and HBeAg-negative patients were randomly selected. UDPS and CBS were used to sequence the basic core promoter/precore region of HBV. Two online bioinformatics tools, the “Deep Threshold Tool” and the “Rosetta Tool” (http://hvdr.bioinf.wits.ac.za/tools/), were built to test and analyze the generated data.

Results

A total of 10952 reads were generated by UDPS on the 454 GS Junior platform. In the four samples, substitutions, detected at 0.5% threshold or above, were identified at 39 unique positions, 25 of which were non-synonymous mutations. Sample #2 (HBeAg-negative, genotype D) had substitutions in 26 positions, followed by sample #1 (HBeAg-negative, genotype E) in 12 positions, sample #3 (HBeAg-positive, genotype D) in 7 positions and sample #4 (HBeAg-positive, genotype E) in only four positions. The ratio of nucleotide substitutions between isolates from HBeAg-negative and HBeAg-positive patients was 3.5∶1. Compared to genotype E isolates, genotype D isolates showed greater variation in the X, basic core promoter/precore and core regions. Only 18 of the 39 positions identified by UDPS were detected by CBS, which detected 14 of the 25 non-synonymous mutations detected by UDPS.

Conclusion

UDPS data should be approached with caution. Appropriate curation of read data is required prior to analysis, in order to clean the data and eliminate artefacts. CBS detected fewer than 50% of the substitutions detected by UDPS. Furthermore it is important that the appropriate consensus (reference) sequence is used in order to identify variants correctly.

The impact of hepatitis B virus precore/core gene carboxyl terminal mutations on viral biosynthesis and the host immune response

BACKGROUND

 We aimed to elucidate the impact of hepatitis B virus (HBV) precore/core gene mutations on spontaneous hepatitis B e antigen (HBeAg) seroconversion, HBV biosynthesis, and the human immune responses in chronic HBV-infected patients.

METHODS

 We analyzed the HBV precore/core gene sequences by cloning method in 33 chronic HBV-infected patients during the inflammatory phase before spontaneous HBeAg seroconversion. The impact of the most prevalent mutant on HBeAg biosynthesis was assessed by Western blotting and native agarose gel analysis in Huh7 cells, and the human immune responses were assessed by in vitro stimulation of CD3+ CD8+ T lymphocytes of chronic HBV-infected subjects.

RESULTS

 The P135Q and G1896A were the most prevalent mutants before HBeAg seroconversion, acting as markers of HBeAg seroconversion (hazard ratios = 2.75 and 4.50; P = .01 and <.001, respectively). The P135Q mutants displayed decreased HBeAg secretion and HBV capsid molecular weight, while showing increased 22 kD HBeAg proprotein accumulation in Huh7 cells. The P135Q mutant peptide induced less interferon-γ expression in CD3+ CD8+ T lymphocytes in HBeAg-negative subjects compared to the wild-type peptide (P = .03).

CONCLUSIONS

 The HBV P135Q mutant emergence during the inflammatory phase was associated with HBeAg seroconversion. It was associated with altered HBV capsid assembly, HBeAg biosynthesis, and reduced human immune responses following HBeAg seroconversion.

Human interleukin-10 genotypes are associated with different precore/core gene mutation patterns in children with chronic hepatitis B virus infection

OBJECTIVE

To elucidate the association between human interleukin-10 (IL-10) genotypes and hepatitis B virus (HBV) precore/core gene mutation in children with chronic HBV infection.

STUDY DESIGN

The study group comprised of 21 children with chronic HBV infection with spontaneous hepatitis B e antigen (HBeAg) seroconversion who were followed for more than 10 years. Another nine children without HBeAg seroconversion served as the control subjects. Sera at the immune tolerance and inflammatory phase (alanine aminotransferase, >80 IU/L) were subjected to HBV precore/core sequence analysis. IL-10 -1082 polymorphism was also determined.

RESULTS

HBV precore/core gene mutation increased significantly more in the inflammatory phase than in the tolerance phase (G1896A, 76.2% versus 4.8%; C1913A, 33.3% versus 0%; C2189A, 28.6% versus 4.8%; G2304A, 52.4% versus 14.3%) in study group (n = 21) but not the control group (n = 9). Subjects with the G/G genotype at the IL-10-1082 polymorphism site had higher C2189A mutation rate than the A allele carriers (P = .02). C2189A mutation carriers are associated with more viral load decrement from tolerance to inflammatory phase (P = .01) and earlier spontaneous HBeAg seroconversion (P = .01).

CONCLUSIONS

The G/G genotype at the IL-10 -1082 polymorphism is associated with higher C2189A mutations, lower HBV viral load at immune inflammatory phase, and earlier spontaneous HBeAg seroconversion than A allele carriers.

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.

Natural history of hepatitis B virus infection: pediatric perspective

Hepatitis B virus (HBV) infection is an important disease globally. Chronic HBV infection may result in serious complications. Its transmission may be either perinatal or horizontal. Perinatal transmission is particularly important after the implementation of a universal vaccination program. Through either route, chronic carrier status is usually established in early childhood. The course of the disease course is determined by the host-virus interaction. The host's immune system initially tolerates the virus, and then gradually attempts to clear it. The virus, on the other hand, tries to avoid host immune system attack by a strategy involving targeted epitope mutations. By generating mutants, the virus can survive attacks from the host's immune system, enabling the infection to persist. Different individuals have different responses to HBV infection; genetic polymorphisms in cytokines, hormones, and other immune modulators may affect the final outcome of chronic HBV infection. Due to the implementation of a universal infant HBV vaccination program, HBV infection is now under control. Unfortunately, there still are some cases of vaccination failure. Very high maternal viremia, in utero infection, or escape mutants are possible reasons for vaccination failure. Immunocompromised hosts also risk vaccination failure. Blood or organ donors with occult HBV infection are possible sources for immunocompromised hosts. These victims of vaccination failure may exhibit a different disease course due to chronic HBV infection from those who acquired the infection before the universal vaccination era. The achievement of our ultimate goal of HBV elimination depends on a globally effective universal vaccination program, as well as the application of some novel successful medications to control those who are already infected.

Pre-S2 deletions of hepatitis B virus and hepatocellular carcinoma in children

The cause of early oncogenesis in hepatitis B virus (HBV)-related childhood hepatocellular carcinoma (HCC) remains unclear. This study investigated whether pre-S deletion of HBV is related to childhood HCC. By using nested polymerase chain reaction, we compared the pre-S sequence of HBV from sera of children with HCC against control children with similar chronic HBV infection. The HBV in sera of children with HCC had a significantly higher rate of pre-S deletion than that of children with chronic HBV infection (p = 0.008). All except one of the pre-S deletions from the HCC group involved the pre-S2 region, whereas no pre-S2 deletion was found in the chronic HBV group (p = 0.003). There was a trend whereby genotype-C sera had a higher rate of pre-S2 deletion than genotype-B sera (p = 0.11). A multivariate logistic regression model revealed that pre-S deletion was an independent risk factor for HCC in children (odds ratio: 36.69, p = 0.015). In conclusion, pre-S2 deletion does not need to take decades to occur; its presence in nearly half of children with HCC, in contrast to its absence in children with chronic HBV infection, suggests a link between pre-S2 deletion and HCC development in children.

Mutations of T-cell epitopes in the hepatitis B virus surface gene in children with chronic infection and hepatocellular carcinoma

BACKGROUND AND OBJECTIVES

Hepatitis B virus (HBV) infection induces an interaction of host immune responses against virus antigen-presenting hepatocytes. The emergence of mutants is a strategy through which the virus can escape host attacks and produce chronic infection. In this study, we aimed to investigate mutations of the human leukocyte antigen-A2-restricted T-cell epitope (TCE) in chronic HBV-infected children.

METHODS

In total, 441 chronic HBV-infected children were longitudinally followed-up every 6 months. They were divided into hepatitis B e antigen (HBeAg) (-) (N = 60) and HBeAg (+) (N = 381) groups according to this seromarker at their enrollment. The HBeAg (+) group was further divided into HBeAg (+/-) (N = 229) and HBeAg (+/+) (N = 152) groups, depending on the occurrence of spontaneous HBeAg seroconversion. Twenty-five children with HBV-related hepatocellular carcinoma (HCC) were also recruited. TCE mutations were examined using the latest serum samples, and serum samples at enrollment were used if TCE mutations were present in the latest serum samples in the seroconverters. HBV genotypes and liver enzymes were also analyzed.

RESULTS

The HBeAg (+/+) group had a lower TCE mutation rate (7.9%) than that of the HBeAg (+/-) (29.2%), HBeAg (-) (26.7%), and HCC (28.0%) groups. In the HBeAg (+/-) group, TCE mutations were present before HBeAg seroconversion in 11.9% of the subjects. Those with TCE mutations showed HBeAg seroconversion at an older age (16.1 +/- 5.3 yr vs 12.7 +/- 5.7 yr, P < 0.001) and with higher peak alanine aminotransferase (ALT) levels (median 175 U/L vs 119 U/L, P = 0.03) than those without TCE mutations.

CONCLUSIONS

TCE mutations tended to be positively associated with HBeAg seroconversion and higher ALT levels in chronic HBV-infected children.

Natural history and clinical management of chronic hepatitis B virus infection in children

Hepatitis B virus (HBV) infection may cause acute, fulminant, or chronic hepatitis, leading to liver cirrhosis or hepatocellular carcinoma. Despite the availability of effective vaccine, HBV infection during infancy or early childhood is common in areas of high endemicity. In these regions, mother-to-infant transmission accounts for approximately 50% of chronic infections. Although the natural history of HBV infection in adults is well characterized, little information is available in the literature regarding the natural history of HBV infection in children. Similar to infection in adults, chronic HBV infection in children can be divided into distinct phases: immune tolerant, immune clearance, and inactive carrier state. However, acute exacerbation, with reactivation of HBV replication and re-elevation of alanine aminotransferase levels after hepatitis B e antigen seroconversion, is relatively rare in children, in comparison to adults. Although several potent antiviral agents are now available for the treatment of chronic hepatitis B, experience with these agents in the pediatric setting is limited. To date, conventional interferon alpha and lamivudine are the only two antiviral agents approved to treat chronic hepatitis B in children. The rapid emergence of resistant HBV associated with long-term lamivudine therapy, as well as poor tolerability associated with conventional interferon alpha, are factors that should be considered before initiating antiviral therapy. This article reviews current knowledge regarding the natural history and treatment of chronic hepatitis B in children. Factors that affect the natural history of HBV infection in children are also reviewed.

Clinical significance and evolution of core promoter and precore mutations in HBeAg-positive patients with HBV genotype B and C: a longitudinal study

BACKGROUND/AIMS

The aims of this longitudinal study were to investigate whether the clinical outcome and evolution of core promoter and precore mutations were different during hepatitis B e antigen (HBeAg) seroconversion between hepatitis B virus (HBV) genotypes B and C in HBeAg-positive patients with chronic hepatitis B.

PATIENTS AND METHODS

The core promoter and precore sequences were determined from serial sera of 156 HBeAg-positive patients with chronic HBV infection.

RESULTS

In HBV genotype C, the T1762/A1764 mutant was detected earlier than the A1896 mutant, and the frequency was significantly higher than in HBV genotype Ba over the entire follow-up period. In HBV genotype Ba, A1896 was found earlier than the T1762/A1764 mutant, and the frequency was significantly higher than in genotype C only before HBeAg seroconversion, and the A1896 mutant played an important role in HBeAg seroconversion in HBV genotype Ba. In addition, the T1846 variant was an independent factor associated with HBeAg seroconversion. Furthermore, HBV genotype C was associated with the development of G or C1753 and T1766/A1768 mutations, and the reactivation of hepatitis after HBeAg seroconversion. Based on Cox's regression analysis, the significant risk factors of liver cirrhosis were older age at entry [hazard ratio (HR)=1.085, 95% confidence interval (CI)=1.036-1.136, P=0.001], alanine transaminase (ALT) >80 U/l (HR=3.48, 95% CI=1.37-8.86, P=0.009), and the T1762/A1764 mutant (HR=5.54, 95% CI=2.18-14.08, P<0.001).

CONCLUSIONS

Our study showed that different HBV genotypes were associated with various mutations in the core promoter and precore regions during HBeAg seroconversion. T1762/A1764 mutation could be useful in predicting clinical outcomes in HBeAg-positive patients with HBV infection.

Presence of hepatitis B virus core promoter mutations pre-seroconversion predict persistent viral replication after HBeAg loss

BACKGROUND

In patients with chronic hepatitis B virus (HBV) infection DNA levels do not always fall after anti-hepatitis B e (anti-HBe) seroconversion.

OBJECTIVES

To follow longitudinally through HB e antigen (HBeAg) loss HBV DNA levels and core promoter/precore sequences in a cohort of 21 chronic HBV carriers.

STUDY DESIGN

Treatment-naïve HBeAg seropositive HBV carriers were monitored through HBeAg loss for between 2 and 22 years (mean 9.3). Core promoter/precore sequences, genotypes, HBV DNA levels and HBe status were determined.

RESULTS

Patients were grouped into those in whom serum/plasma HBV DNA remained high after HBeAg loss (group 1, n=11; HBV DNA>5log(10)IU/ml) and those in whom HBV DNA declined (group 2, n=10). Re-appearance of HBeAg was seen in seven group 1 patients. Pre-seroconversion mutations in the core promoter region including A1762T and/or G1764A were detected more frequently in group 1 (P=0.031). Overall sequence changes at sites other than 1762/1764 were more common post-seroconversion in group 1 than group 2 patients (P=0.037).

CONCLUSIONS

The presence of core promoter mutations prior to HBeAg loss identified those patients in whom HBV DNA persisted at high levels and was associated with temporary re-emergence of serum HBeAg. These patients may benefit from early anti-viral treatment.

Viremia profiles in children with chronic hepatitis B virus infection and spontaneous e antigen seroconversion

BACKGROUND & AIMS

This study investigated the viremia profiles in children with chronic hepatitis B virus (HBV) infection and spontaneous hepatitis B e antigen (HBeAg) seroconversion.

METHODS

Fifty-eight children with chronic HBV infection met the following criteria: normal alanine aminotransferase (ALT) level at enrollment, followed up for more than 10 years, no antiviral treatment, and having undergone spontaneous HBeAg seroconversion during follow-up evaluation. They were grouped according to the post-HBeAg seroconversion HBV-DNA levels: (1) low viremia: transient or never 10(4) copies/mL or greater (n=35) (2) fluctuating high viremia: 10(4) copies/mL or greater at least twice at intervals more than 1 year apart (n=23). Abdominal sonography, ALT, and HBV-DNA levels were assessed annually. Another 14 nonseroconverted children served as controls. The precore mutant (nt1896) and genotypes were examined.

RESULTS

The initial HBV-DNA level of the 58 seroconverters was 10(8.4+/-1.0) copies/mL and decreased to 10(2.9+/-2.0) copies/mL at the end of follow-up period. Their mean ages at enrollment, at peak HBV-DNA, at peak ALT, at HBeAg seroconversion, and at final follow-up were 7.0 +/- 3.7, 13.4 +/- 5.8, 16.3 +/- 6.0, 17.2 +/- 5.8, and 23.7 +/- 4.1 years, respectively. The precore mutant appeared more often in the fluctuating-high-viremia group than in the low-viremia group (60.9% vs 22.9%, P=.004). HBV genotypes had no effect on the viremia profiles. After HBeAg seroconversion, none had persistent abnormal ALT levels.

CONCLUSIONS

Generally, these young seroconverters had decreased viral loads, normal ALT levels, and uneventful courses after HBeAg seroconversion. A longer follow-up period is necessary to elucidate the significance of HBeAg seroconversion occurring in childhood and young adulthood.

Hepatitis B virus mutation in children

Due to the lack of proof reading activity of hepatitis B virus (HBV) polymerase, mutation/variation of the viral sequence is frequently found during long term follow-ups. In the majority of children with chronic HBV infection, wild type HBV is the dominant viral strain during the natural course of chronic HBV infection. During long-term follow-up, HBV precore mutants developed spontaneously in approximately 10 to 24% of children before HBeAg seroconversion and in around 50% of children after HBeAg seroconversion mutants. Occasionally, children may be infected primarily by mutant strains of HBV. Approximately 36% of children with fulminant hepatitis and 30% of children with acute hepatitis B were infected by precore mutants of HBV transmitted by their mothers or blood donors. In addition, after universal HBV vaccination, HBV surface gene variants emerge or are selected under the immune pressure generated by the host or by administration of hepatitis B immune globulin and hepatitis B vaccination. In HBV DNA positive children from four sequential surveys in Taiwan, the prevalence of hepatitis B surface gene a determinant mutants increased from 7.8% before the vaccination program, to 19.6%, 28.1% and 23.1% at 5, 10 and 15 years after the program. Nucleoside analogue may also induce mutant strains, which reduces the antiviral effects. The most common example is the YMDD mutation of the HBV polymerase gene after antiviral therapy with lamivudine. It developed in 19% of the treated children. In conclusion, children may be infected primarily by mutant strains of HBV either naturally during acute HBV infection. Those infected with wild type HBV initially may develop mutant strains gradually during the course of chronic infection under the host immune pressure. Vaccine escape mutants may develop after immunoprophylaxis. In addition, antiviral therapy with nucleoside analogues may also induce drug resistant mutant strains. Understanding the viral mutation status will help to design accurate strategies of immmunoprophylaxis and antiviral therapy against HBV infection.

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Comparison of sequence changes of precore and core promoter regions in HBeAg-positive chronic hepatitis B patients with and without HBeAg clearance in lamivudine therapy

BACKGROUND/AIMS

The aim of this study was to compare the serial sequence changes of precore and core promoter regions in hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) patients with and without HBeAg clearance in lamivudine treatment.

METHODS

Precore and core promoter genes of the hepatitis B virus (HBV) were sequenced from five serial serum samples of 74 HBeAg-positive CHB patients received lamivudine for 9-12 months (34 complete responders and 40 non-responders).

RESULTS

Before lamivudine therapy, stepwise logistic regression analysis disclosed that ALT level > or =300 U/L, A1896 mutant, and log HBV DNA levels were the major determinants for complete response. In addition, Cox regression showed that age < 35 years and G1752 mutant were independent factors for sustained response. Compared with complete responders, a higher frequency of mutation in nucleotides 1773, 1802, 1803, 1845, 1850, and 1858 was found in the non-responders during therapy. Lamivudine therapy resulted in a further increase in T1762/1764 mutants and a further decrease in A1896 mutant during treatment and after HBeAg clearance in complete responders.

CONCLUSIONS

T1762/A1764 mutation (not A1896) played an important role in lamivudine-induced HBeAg clearance. Moreover, T1773, C1802, G1803, T1846, A1850, and C1858 mutations might have significant correlation with HBeAg nonseroconversion.

Hepatitis B virus and hepatitis C virus infections in children

PURPOSE OF REVIEW

To analyse the most relevant recent information on efficacy, duration and coverage of anti-hepatitis B virus vaccination; correlates of mother-to-child hepatitis C virus transmission; the natural history and outcomes of hepatitis B and C virus infections in children; the efficacy and safety of specific therapies.

RECENT FINDINGS

Insufficient hepatitis B virus vaccine coverage and incomplete or delayed vaccine cycles need improvement in many countries. Hepatitis B virus mutants may explain some fulminant hepatitis in perinatally infected infants and vaccine failures. No interventions to prevent vertical hepatitis C virus transmission have been identified. Spontaneous clearance of hepatitis B is lower in children than in adults, while the rates appear to be similar for hepatitis C. The disease progression is slower for both infections in childhood. Several studies support the efficacy and safety of interferons and lamivudine in chronic hepatitis B or of interferons and ribavirin in chronic hepatitis C in children, but the optimal therapy remains unclear.

SUMMARY

There are doubts as to the long-term persistence of anti-hepatitis B immunization in low-endemicity areas. Routine hepatitis C virus testing in pregnancy is not recommended as there are no available prophylactic measures. Although hepatitis B and C virus infections are usually asymptomatic or with mild manifestations in childhood, concerns around their long-term clinical impact suggest the need for early treatment. Children should preferably be treated in the context of targeted trials for a better understanding of the efficacy and tolerance of drugs currently used in adults.

HBx M130K and V131I (T-A) mutations in HBV genotype F during a follow-up study in chronic carriers

BACKGROUND

Around 400 million people worldwide are chronically infected with Hepatitis B virus (HBV). An estimated 10% of these chronic patients develop progressive liver damage including cirrhosis and Hepatocellular Carcinoma (HCC). The HBx gene encodes a protein of 154 amino acids which is a transactivator and has been associated with HBV pathogenesis. A change in the amino acid sequences at positions 130 and 131 in the HBV-X protein (M130K and V131I) produced by T-A point mutations at the nucleic acids level has been associated with severe liver damage and HCC in patients from China and Africa. Further, such changes have been proposed as a prognostic marker for progressive liver damage and HCC. The purpose of this study was to determine if T-A mutations are present in HBV chronic carriers with genotype F (the major genotype in Costa Rica) and further, if these mutations are associated with HBV disease progression in Costa Rica HBV patients from 1972 to 1985.

RESULTS

Serum samples from 50 HBV positive individuals were amplified and directly sequenced, 48 belonged to genotype F, 1 from genotype D and another was classified as D or E. T-A mutations were absent in 17 acute patients who recovered, but was present in 12 of 29 chronic carrier samples (42.8%), in one sample the T-A mutations were detected as early as 29 days after clinical onset of disease. In 17 carriers with available liver biopsies, T-A mutations were found in 8 sera of 13 (61.5%) classified as moderate or severe, and none in 4 biopsies with mild liver damage. However, it was not possible to demonstrate a statistical association between the presence of T-A mutations and moderate/severe liver damage, using a Fischer exact test, 1 tail, p = 0.05. In 4 patients HCC was diagnosed, and 2 of them presented the T-A mutations in their sera.

CONCLUSION

T-A mutations were found in HBV genotype F in chronic carriers but not in patients who recovered from acute infection. These mutations could be developing early during infection although the possibility of infection with the mutant virus could not be excluded. More studies are necessary to establish if the T-A mutation can be used as a prognostic marker for severity of liver disease in patients infected with HBV.

Clinical relevance of hepatitis B virus genotype in children with chronic infection and hepatocellular carcinoma

BACKGROUND & AIMS

The aim of this study was to investigate the influence of hepatitis B virus (HBV) genotypes on the clinical outcome of chronic childhood HBV infection and hepatocellular carcinoma (HCC).

METHODS

A total of 460 HBV carrier children were followed-up for 15 years and 26 children with HBV-related HCC were recruited. HBV genotyping was examined at enrollment and the latest follow-up of these carrier children and at diagnosis in HCC children. Viral load was checked at enrollment for the carrier children. These carriers were grouped based on their initial hepatitis B e antigen (HBeAg) and antibody to hepatitis B e antigen (anti-HBe) status. The HBeAg positive (+) group was divided further into an HBeAg(+/+) group and HBeAg(+/-) group, depending on whether spontaneous HBeAg seroconversion occurred during the follow-up period.

RESULTS

Genotype B constituted 73%, 86%, and 76% in the HBeAg(+/+), HBeAg(+/-), and anti-HBe(+) groups, respectively. Genotype C was found in 27%, 8%, and 6% in the HBeAg(+/+), HBeAg(+/-), and anti-HBe(+) group, respectively. Genotype C carriers were more prevalent in the HBeAg(+/+) group than the other 2 groups (P = .01), and had a delayed HBeAg seroconversion compared with the genotype B carriers (P < .001). Changes of genotype during the follow-up period were rare (2.8%). In those with HCC, genotype B was also the major type (74%). There was no difference in the baseline viral load between genotypes B and C.

CONCLUSIONS

Although HBV genotype B dominates in children with chronic HBV infection and HCC in Taiwan, genotype C delays HBeAg seroconversion in pediatric chronic HBV infection.