Hepatitis B virus core promoter mutations in children with multiple anti-HBe/HBeAg reactivations result in enhanced promoter activity

Fatal fulminant hepatitis caused by infection with subgenotype A1 hepatitis B virus with C1766T/T1768A core promoter mutations

Adults initially infected with the hepatitis B virus develop various types of hepatitis ranging from asymptomatic to fulminant, and the clinical course of infection is influenced by a variety of host and viral factors. The viral risk factors associated with fulminant hepatitis reportedly include subgenotype B1, negative HBe antigen, and mutations in the precore and core promoter regions. Here, we present a case of fatal fulminant hepatitis caused by infection with subgenotype A1 hepatitis B virus with C1766T/T1768A double mutations in the core promoter region. A 53-year-old man was hospitalized with acute hepatitis B. Immediately after admission, entecavir was administered. However, his condition deteriorated, developing into fulminant hepatitis 2 days later. Artificial extracorporeal liver support therapy with plasma exchange (PE) and hemodiafiltration (HDF) were started. At one time point, the severity of hepatic encephalopathy decreased from grade II to grade 0, and the prothrombin time also improved, increasing from 11 to 73 %. However, the total bilirubin levels remained at or above 20 mg/dL and blood creatinine levels gradually increased. HDF was restarted, and therapies such as bilirubin adsorption and PE were administered. However, neither hepatic nor renal failure was alleviated, and the patient died 78 days after admission.

Asian-Pacific clinical practice guidelines on the management of hepatitis B: a 2015 update

Worldwide, some 240 million people have chronic hepatitis B virus (HBV), with the highest rates of infection in Africa and Asia. Our understanding of the natural history of HBV infection and the potential for therapy of the resultant disease is continuously improving. New data have become available since the previous APASL guidelines for management of HBV infection were published in 2012. The objective of this manuscript is to update the recommendations for the optimal management of chronic HBV infection. The 2015 guidelines were developed by a panel of Asian experts chosen by the APASL. The clinical practice guidelines are based on evidence from existing publications or, if evidence was unavailable, on the experts' personal experience and opinion after deliberations. Manuscripts and abstracts of important meetings published through January 2015 have been evaluated. This guideline covers the full spectrum of care of patients infected with hepatitis B, including new terminology, natural history, screening, vaccination, counseling, diagnosis, assessment of the stage of liver disease, the indications, timing, choice and duration of single or combination of antiviral drugs, screening for HCC, management in special situations like childhood, pregnancy, coinfections, renal impairment and pre- and post-liver transplant, and policy guidelines. However, areas of uncertainty still exist, and clinicians, patients, and public health authorities must therefore continue to make choices on the basis of the evolving evidence. The final clinical practice guidelines and recommendations are presented here, along with the relevant background information.

Variability in the precore and core promoter region of the hepatitis B virus genome

There is increasing evidence that hepatitis B virus (HBV) infections with different genotypes and subgenotypes differ in response to treatment and long-term prognosis. The differences emerge from variability within the genomes that leads to structural deviations at the pregenomic level and to changes at the translational level. Naturally occurring HBV strains covering the four major genotypes A-D were obtained from 393 patients and part of the genome was amplified using polymerase chain reaction (PCR), sequenced, and analyzed for mutational differences in the precore and core promoter regions. The study confirmed that core promoter and precore mutations occur at key positions (A1762T, G1764A, G1896A, and G1899A), and that the proportions of strains with seroconvertion in patients differ between the four HBV genotypes. A rare double mutation (C1857T together with G1897A) was observed, and C1856T was found together with the emerging G1898A mutation, which itself was found to be more widespread geographically than previously described. We found a novel mutation (T1850C), never before observed in human HBV strains but known from woodchuck hepatitis virus (WHV). A novel association of mutation C1773T with G1764T, C1766A, and G1757A was also found within a site already suggested to be a putative binding site for HNF-3. This novel association is proposed by us to be of importance for additional binding of HNH-2 to this site and is a better indicator of the emergence of the double mutation G1764T and C1766A than the G1757A mutation proposed previously.

Genomic analysis of hepatitis B virus reveals antigen state and genotype as sources of evolutionary rate variation

Hepatitis B virus (HBV) genomes are small, semi-double-stranded DNA circular genomes that contain alternating overlapping reading frames and replicate through an RNA intermediary phase. This complex biology has presented a challenge to estimating an evolutionary rate for HBV, leading to difficulties resolving the evolutionary and epidemiological history of the virus. Here, we re-examine rates of HBV evolution using a novel data set of 112 within-host, transmission history (pedigree) and among-host genomes isolated over 20 years from the indigenous peoples of the South Pacific, combined with 313 previously published HBV genomes. We employ Bayesian phylogenetic approaches to examine several potential causes and consequences of evolutionary rate variation in HBV. Our results reveal rate variation both between genotypes and across the genome, as well as strikingly slower rates when genomes are sampled in the Hepatitis B e antigen positive state, compared to the e antigen negative state. This Hepatitis B e antigen rate variation was found to be largely attributable to changes during the course of infection in the preCore and Core genes and their regulatory elements.

[Natural history and clinical manifestations of chronic hepatitis B virus]

Hepatitis B virus (HBV) infection is a serious public health problem worldwide. In the last few decades, major advances have been achieved that have contributed to greater understanding of the natural history and clinical manifestations of this infection. The fluctuation between viral replication and the host's immune response has implications in the pathogenesis and progression of the hepatic lesion. In immunocompetent adults, most HBV infections resolve spontaneously in contrast with progression to chronic infection in most infants. Patients with chronic hepatitis due to HBV or chronic hepatitis B can present at four phases: 1) the immune tolerance phase, 2) HBeAg-positive chronic hepatitis B, 3) inactive HBsAg carrier state, and 4) HBeAg-negative chronic hepatitis. HBeAg-positive or -negative chronic hepatitis can progress to cirrhosis, liver failure and hepatocellular carcinoma. Progression to these complications is more frequent in HBeAg-negative forms, associated with mutations that affect the pre-core region and maintain active viral replication. Risk factors are HBV-DNA positive serum levels, an increase in serum transaminase levels and some genotypes. These factors highlight the need to evaluate and monitor all HBV carriers to identify those who could benefit from early antiviral treatment, thus avoiding progression to more advanced forms of liver disease. These measures could improve prevention and treatment of hepatitis B.

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.

High level of genetic heterogeneity in S and P genes of genotype D hepatitis B virus

The genetic heterogeneity of hepatitis B virus (HBV) genotypes and subgenotypes was investigated by directly sequencing amplified PreS, S and P genes of HBV isolates obtained from the plasma of 99 subjects with chronic HBV infection. Genotype D showed the greatest intragenotypic and intrasubgenotypic divergence: in particular, the a determinant was mutated in 58.2% of the genotype D patients, two of whom showed prototypic vaccine-induced escape mutants at codon 145. Moreover, five sites under significant positive selection were found in the S protein of the D isolates: one in the a determinant and four in the highly hydrophobic C terminal. Our results suggest that careful surveillance of vaccine-induced escape mutants should be considered in populations with highly frequent genotype D infections, and raise questions concerning the possible relationship between the genetic heterogeneity, host immunity and pathogenicity of this HBV genotype.

Genome-wide characterisation of hepatitis B mutations involved in clinical outcome

Infection with the hepatitis B virus (HBV) leads to different disease outcomes, which can be broadly divided into three categories: acute mild infection, 'fulminant' and chronic hepatitis (long-term persistent form of the infection). The factors that influence the development of these different disease states are poorly understood and may include viral polymorphisms. To investigate this possibility, we analysed 116 published complete HBV genomes for which we knew disease outcome and had access to associated information on patients (age, sex and geographic origin). Our best statistical model correctly classified 72% of the cases and retained age and sex of the patient, as well as 29 candidate mutations. With the exception of one mutation in the X gene, all were located in the viral polymerase, suggesting this gene plays a critical role in clinical outcome. Our results highlight the importance of the genetics of HBV strains in the evolution of the disease and demonstrate that disease outcome can be predicted to a surprisingly large extent with a limited number of host and viral factors.

T1764G1766 core promoter double mutants are restricted to Hepatitis B virus strains with an A1757 and are common in genotype D

To investigate the role of pre-core and basal core promoter (BCP) mutants in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (e-CHB) in Iran, Hepatitis B virus strains from 30 patients and 42 anti-HBe-positive asymptomatic carriers (ASCs) were characterized. G1896A pre-core stop mutants, detected in 77 % of e-CHB patients and 85 % of ASCs, showed no association with virus load or aminotransferase levels. Twenty per cent of e-CHB patients and 31 % of ASCs harboured T1762A1764 mutants. When this double mutation was associated with G1757, it was linked to a higher virus load in patients than when it was associated with A1757 (10(5.2+/-1.8) vs 10(3.2+/-0.8) copies ml(-1); P=0.004). Interestingly, the most common BCP mutations were T1764 and G1766, which were present in 33 % of e-CHB patients and 29 % of ASCs. These were associated with higher virus load and aminotransferase levels compared with patients lacking core promoter mutations, although this was not significant. The T1764G1766 double mutation was only present in strains with A1757 (P<0.001), which is more frequent in strains of genotype D than in those belonging to other genotypes. On the other hand, the T1762A1764 double mutation was found more frequently in association with G1757 than with A1757. The T1762A1764 double mutation forms a binding site for hepatocyte nuclear factor 1 (HNF1), which is constrained by A1757. However, the T1764G1766 double mutant may form a binding site for HNF3. Thus, position 1757 affects the emergence of promoter double mutants and would predict a relative genotypic restriction of both the T1762A1764 and the T1764G1766 double mutants.

Optimization of competitively differentiated polymerase chain reaction in detection of HBV basal core promoter mutation

AIM: To improve competitively differentiated polymerase chain reaction (CD-PCR) in detection of HBV basal core promoter mutation.

METHODS: Recombinant plasmid of double point mutation A1762T/G1764A in basal core promoter of HBV constructed by site-directed mutagenesis was used as mutant control. To reveal the deficiency mechanism of CD-PCR, relationship between the circle number of PCR and the increased speed of products of each competitive primer was comparatively studied. Diversified amount of dNTPs and mutual primer of the competitive primers were tried to optimize CD-PCR. Optimized CD-PCR was evaluated by detecting A1762T/G1764A mutation in recombinant plasmids and clinical sera from patients with HBV infection.

RESULTS: The deficiency mechanism of CD-PCR was that the products of mismatched competitive primer grew fast when the amplification of matched primer entered into plateau stage, which led to decrease in or disappearance of the difference in the amount of their products. This phenomenon could be eliminated by reducing dNTPs to 10 μmol/L and mutual primer to about 100 nmol/L. Optimized CD-PCR could detect both mutant and wild strain indepe-ndent of the amount of templates and the number of PCR cycles. Its detection limit was 10³ copies/mL, about 50 copies/reaction. About 10% of mutant DNAs among wild type DNAs could be detected. A1762T/G1764A mutant was detected in 41.8% (51/122) of patients with HBV infection, but not detected in controls with negative HBsAg.

CONCLUSION: Optimized CD-PCR can detect mutation independent of the amount of initial templates and the number of PCR cycles.

High level of hepatitis B virus DNA after HBeAg-to-anti-HBe seroconversion is related to coexistence of mutations in its precore and basal core promoter

AIM: G1896A mutation in precore or A1762T/G1764A mutations in basal core promoter are suspected to be responsible for patients with detectable level of HBV DNA in serum after seroconversion from HBeAg to anti-HBe. However, G1896A variant has impaired, while A1762T/G1764A variant may have intact replication ability. They themselves or their coexistence status may play different roles in such meaningless seroconversion. For these reasons, the significances of these two types of mutations were comparatively investigated in this study.

METHODS: One hundred and sixty-five sera with positive anti-HBe and HBV DNA were collected from different patients. Mutations of G1896A and A1762T/G1764A among these serum samples were detected using competitively differentiated PCR. HBV DNA was demonstrated using real-time quantitative PCR.

RESULTS: G1896A and/or A1762T/G1764A mutations were detected in 89.1% (147/165) out of patients with detectable HBV DNA in serum after HBeAg-to-anti-HBe seroconversion. The positive rate of G1896A variants was significantly higher than that of A1762T/G1764A mutations (77.6% vs 50.3%, χ² = 26.61, P<0.01). The coexistence positive rate of these two types of mutations was 38.8% (64/165). Coexistence mutations were found in 77.1% (64/83) out of sera with A1762T/G1764A mutations, and in 50.0% (64/128) out of sera with G1896A mutation. Compared with variants with G1896A mutation only, the coexistence mutations were predominant in patients with high level of serum HBV DNA, and related to higher total bilirubin, lower serum albumin and progressive liver diseases.

CONCLUSION: The coexistence of G1896A mutation and A1762T/G1764A mutations is very common, and responsible for the major cases with high level of HBV DNA in serum and progressive liver diseases after HBeAg-to-anti-HBe seroconversion. This coexistence mutation variant may have higher pathogenicity and replication ability.

Hepatitis B: epidemiological, immunological, and serological considerations emphasizing mutation

The global prevalence of hepatitis B virus is estimated to be 350 million chronic carriers, varying widely from low (<2%, as in Western Europe, North America, New Zealand, Australia, and Japan) to high (>8% as in Africa, Southeast Asia, and China). The overall prevalence in Brazil is about 8%. There are currently 7 genotypic variations, from A to G, and also 4 main surface antigen subtypes: adw, ayw, adr, and ayr. There has been great interest in identifying the geographic distribution and prognosis associated with the various genotypes and subtypes. Although the serologic test is highly sensitive and specific, it does not detect cases of mutant hepatitis B, which is increasingly common worldwide due to resistance and vaccine escape, antiviral therapy, and immunosuppression, among other causes. Alterations in surface, polymerase, X region, core, and precore genes have been described. The main mutations occur in surface and in core/precore genes, also known as occult hepatitis, since its serologic markers of active infection (HBsAg) and viral replication (HBeAg) can be negative. Thus, mutation should be suspected when serologic tests to hepatitis B show control of immunity or replication coincident with worsened clinical status and exclusion of other causes of hepatitis.

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Genotype H: a new Amerindian genotype of hepatitis B virus revealed in Central America

The complete genomes were sequenced for ten hepatitis B virus (HBV) strains. Two of them, from Spain and Sweden, were most similar to genotype D, although encoding d specificity. Five of them were from Central America and belonged to genotype F. Two strains from Nicaragua and one from Los Angeles, USA, showed divergences of 3.1-4.1% within the small S gene from genotype F strains and were recognized previously as a divergent clade within genotype F. The complete genomes of the two genotype D strains were found to differ from published genotype D strains by 2.8-4.6%. Their S genes encoded Lys(122), Thr(127) and Lys(160), corresponding to the putative new subtype adw3 within this genotype, previously known to specify ayw2, ayw3 or, rarely, ayw4. The complete genomes of the three divergent strains diverged by 0.8-2.5% from each other, 7.2-10.2% from genotype F strains and 13.2-15.7% from other HBV strains. Since pairwise comparisons of 82 complete HBV genomes of intratypic and intertypic divergences ranged from 0.1 to 7.4% and 6.8 to 17.1%, respectively, the three sequenced strains should represent a new HBV genotype, for which the designation H is proposed. In the polymerase region, the three strains had 16 unique conserved amino acid residues not present in genotype F strains. So far, genotype H has been encountered in Nicaragua, Mexico and California. Phylogenetic analysis of the complete genomes and subgenomes of the three strains showed them clustering with genotype F but forming a separate branch supported by 100% bootstrap. Being most similar to genotype F, known to be an Amerindian genotype, genotype H has most likely split off from genotype F within the New World.

Acute flares in chronic hepatitis B: the natural and unnatural history of an immunologically mediated liver disease

Acute flares in chronic hepatitis B are common and may be caused by a number of identifiable and potentially treatable factors. The common link for many of these exacerbation episodes is a change in the immunologic response to hepatitis B virus (HBV), and this may have no identifiable cause or be triggered by an increase in viral replication or genotypic change. It is important to keep in mind the clinical situations in which patients are at increased risk of reactivated infection and secondary exacerbations. Reactivation is frequently induced by medical treatments such as cancer chemotherapy, antirejection drugs used in organ transplantation, and corticosteroids. The immunologic flares that often result from sudden withdrawal of these medications can be life-threatening unless recognized and treated promptly with antivirals, and there is increasing experience that preemptive antiviral treatment can diminish their occurrence and improve the outcome. The experience with lamivudine and other nucleoside analogues has increased our understanding of the molecular events behind hepatitis flares that occur when chronic hepatitis B is treated with drugs that potently inhibit HBV DNA polymerase. However, not all flares are explainable by events related to HBV infection alone. Depending on the population studied, as many as 20%-30% of flares may be caused by infection with other hepatotropic viruses, and this situation may inhibit HBV replication. Proper understanding of the etiology and effective treatment of acute flares in chronic hepatitis B requires an appreciation of high-risk clinical situations, assessment of HBV replication status, and testing for other viruses when appropriate.

Genetic variations of hepatitis B virus

The emergence of hepatitis B virus genetic variants occurs under the influence of host immunity, immunization, the use of immune globulin or antiviral chemotherapy. Most of these are probably the result of the 'immune escape' phenomenon. Some variants, in particular those in the precore and core promoter regions, have been associated with disease severity and progression. Surface antigen variants have implications for the accuracy of laboratory diagnosis and may reduce the effectiveness of vaccination. Polymerase variants are selected as a result of the use of antiviral chemotherapeutic agents. It is important to monitor the occurrence of these variants.