Probable implication of mutations of the X open reading frame in the onset of fulminant hepatitis B

Analysis of full-length hepatitis B virus genome from chronic hepatitis B-patients with higher alanine aminotransferase elevation

Background & aim: Higher elevation of alanine aminotransferase (ALT) occasionally leads to severe outcomes in hepatitis B virus (HBV)-infected patients. Our aim is to investigate the HBV sequence mutations associated with higher ALT elevation. Materials & methods: We analyzed full-length HBV sequences from patients with or without higher ALT elevation. Results: Nucleotide mutations in precore and core regions, which are associated with severe hepatitis B, were found in two HBV-infected patients with higher ALT elevation. Amino acid mutations within the pre-S1, pre-S2 and S regions were also found in a patient with HBV virologic breakthrough during the use of nucleoside analogs. Conclusion: It may be useful for HBV-infected patients with higher ALT elevation to analyze full-length HBV genome.

Clinical Manifestations and Laboratory Tests of AECHB and Severe Hepatitis (Liver Failure)

This chapter describes the clinical symptoms and signs of AECHB and HBV ACLF, classification, grading of HBV ACLF and their features, diagnostic principles and standards in liver pathology, biochemistry, and virology of HBV ACLF.

Liver failure is defined as serious damage to the liver cause by a variety of etiologies, leading to liver function disorder or even decompensation, and clinical syndromes with coagulopathy, jaundice, hepatic encephalopathy, and ascites.

Severe hepatitis B can be indicated pathologically by apparent hepatocellular necrosis, including extensive multifocal, confluent, bridging, sub-massive or massive necrosis.

Laboratory tests during the course of severe exacerbation of chronic hepatitis B can reflect pathological changes and liver function in a timely manner, providing objective and informative reference data for evaluation of disease severity and treatment efficacy. Among the most important laboratory tests are those for prothrombin activity, international normalized ratio, and increases in total bilirubin concentration.

Severe hepatitis B is associated with interactions between the virus and host factors. Detection of HBV DNA, HBV genotype, quasispecies and HBV mutation can provide important theoretical bases for the prevention, control or mitigation of the progress of severe hepatitis B.

Noninvasive imaging modalities can be used to visualize the entire liver and parts of it. Measuring liver volume to evaluate liver size and liver reserve capacity is regarded as important in diagnosis, surgical approach and prognostic evaluation of patients with severe exacerbation of chronic hepatitis B and liver failure.

Model for End-Stage Liver Disease (MELD) is the first quantitative method developed to assess whether a patient with liver failure requires a liver transplant. The predictive value of the MELD model has been improved by the MELD-Na, iMELD, and MESO models. Several other valuable prognostic models have been developed. For example, for patients with HBV-ACLF, the established TPPM scoring system was found to be more predictive than MELD score.

What is changed in HBV molecular epidemiology in Italy?

Hepatitis B virus (HBV) infection represents the most common cause of chronic liver diseases worldwide. Consequently, to the introduction of the universal HBV vaccination program, the prevalence of hepatitis B surface antigen was markedly reduced and less than 1% of the population of Western Europe and North America is chronically infected. To date, despite great advances in therapeutics, HBV chronic infection is considered an incurable disease. Ten hepatitis B virus genotypes (A-J) and several subgenotypes have been identified so far, based on intergroup divergences of 8% and 4%, respectively, in the complete viral genome. HBV-D genotype has been found throughout the world, with highest prevalence in the Mediterranean area. In the present review, several articles concerning HBV epidemiology, and phylogeny in Italy have been analyzed, mainly focusing on the changes occurred in the last decade.

HBV X gene point mutations are associated with the risk of hepatocellular carcinoma: A systematic review and meta-analysis

Previous evidence suggests that the accumulation of the hepatitis B virus (HBV) X gene region point mutations may be associated with the development of hepatocellular carcinoma (HCC). However, the pathogenesis of HCC remains to be elucidated. The aim of the present meta-analysis was to investigate the association between the HBV X gene point mutations and the risk of HCC. Studies were collected regarding the association between HBV X gene point mutations and the risk of HCC, which were identified in PubMed, EMBASE and China National Knowledge Infrastructure databases. The results were evaluated by use of odds ratios (ORs) and its 95% confidence intervals (CIs), which were pooled by random or fixed effects. A total of 11 studies involving 2,502 patients were included in this meta-analysis. Statistical summary ORs of HBV X gene point mutations were obtained for T1653 (OR, 3.11; 95% CI, 2.22-4.36), V1753 (OR, 2.55; 95% CI, 1.66-3.92), and T1762/A1764 (OR, 4.49; 95% CI, 2.86-7.07). HBV X gene point mutations T1653, V1753 and T1762/A1764 could increase the risk of HCC significantly, particularly the T1762/A1764 double mutations. These mutations may be predictive for hepatocarcinogenesis. However, these results of the meta-analysis should be treated carefully due to a low level of evidence.

Genomic Diversity of Hepatitis B Virus Infection Associated With Fulminant Hepatitis B Development

CONTEXT

After five decades of Hepatitis B Virus (HBV) vaccine discovery, HBV is still a major public health problem. Due to the high genetic diversity of HBV and selective pressure of the host immune system, intra-host evolution of this virus in different clinical manifestations is a hot topic of research. HBV infection causes a range of clinical manifestations from acute to chronic infection, cirrhosis and hepatocellular carcinoma. Among all forms of HBV infection manifestations, fulminant hepatitis B infection possesses the highest fatality rate. Almost 1% of the acutely infected patients develop fulminant hepatitis B, in which the mortality rate is around 70%.

EVIDENCE ACQUISITION

All published papers deposited in Genbank, on the topic of fulminant hepatitis were reviewed and their virological aspects were investigated. In this review, we highlight the genomic diversity of HBV reported from patients with fulminant HBV infection.

RESULTS

The most commonly detected diversities affect regulatory motifs of HBV in the core and S region, indicating that these alterations may convert the virus to an aggressive strain. Moreover, mutations at T-cell and B-cell epitopes located in pre-S1 and pre-S2 proteins may lead to an immune evasion of the virus, likely favoring a more severe clinical course of infection. Furthermore, point and frame shift mutations in the core region increase the viral replication of HBV and help virus to evade from immune system and guarantee its persistence.

CONCLUSIONS

Fulminant hepatitis B is associated with distinct mutational patterns of HBV, underlining that genomic diversity of the virus is an important factor determining its pathogenicity.

Synergistic effects of A1896, T1653 and T1762/A1764 mutations in genotype c2 hepatitis B virus on development of hepatocellular carcinoma

The effects of genomic changes in hepatitis B virus (HBV) on the occurrence of hepatocellular carcinoma (HCC) are still unclear, especially in relation to the genotype of HBV. In this study, we examined the effects of genomic changes in HBV of genotype C2 on the development of HCC. A total of 318 patients with HBV-associated HCC and 234 patients with chronic hepatitis B (CHB) were studied. All of HCC cases were diagnosed histologically and treated with surgical resection. The whole of the X, S, basal core promoter (BCP) and precore regions of the viral genome from sera or liver tissues were sequenced. All subjects had HBV of genotype C2. The prevalence of the T1653 mutation in the X region and the A1896 mutation in the precore region of HBV was significantly higher in the HCC group than in the control CHB group (22% vs 11%, P = 0.003; 50% vs 23%, P < 0.001, respectively). Moreover, the T1762/A1764 mutations in the BCP region in combination with either T1653 or A1896 were more common in the HCC compared with the CHB group (BCP+X1653: 18% vs 11%, P = 0.05; BCP+PC, 40% vs 15%, P < 0.001, respectively). In multivariate analysis, T1653 and A1896 were revealed to be independent risk factors for HCC development. G1896A in the precore region and C1653T mutation in the X region of genotype C2 HBV are important risk factors for HCC development. Also, the A1762T/G1764A double mutation may act in synergy with C1653T to increase the risk of HCC in patients chronically infected with HBV genotype C2.

T1653 mutation in the enhancer II region of the hepatitis B virus genome in southern African Blacks with hepatocellular carcinoma

BACKGROUND

An increased incidence of C-to-T1653 transversion (T1653) in the enhancer II region of the core promoter of hepatitis B virus has been reported in Japanese and Chinese patients with hepatocellular carcinoma infected with genotypes B or C of the virus, but little information is available in patients infected with other genotypes.

AIM

To document the prevalence of T1653 in Black Africans with hepatocellular carcinoma, in whom genotype A is the dominant genotype and subgenotype A1 the dominant subgenotype, and to correlate its presence with other core promoter mutations previously described in association with T1653.

METHODS

The presence of the mutations was determined in 84 patients with hepatitis B virus-induced hepatocellular carcinoma and 50 matched asymptomatic carriers of the virus by extracting viral DNA from serum, amplification by polymerase chain reaction assay, and nucleotide sequencing.

RESULTS

T1653 was not found significantly more often in the cancer patients with genotype A and subgenotype A1 than in the controls. An association was found not only between T1653 and T1762, A1764 and dual T1762/A1764 in the patients with hepatocellular carcinoma, but also in the asymptomatic carriers.

CONCLUSION

T1653 mutation of hepatitis B virus does not occur more often in Black African patients with hepatocellular carcinoma with genotype A and subgenotype A1 than in asymptomatic carriers of the virus. No correlation specific to hepatocellular carcinoma was found between T1653 and other core promoter mutations in these patients. The presence of the T1653 mutation did not influence the e antigen status of the patients.

Correlation of different hepatitis B virus gene mutations with the development of hepatitis B virus-associated glomerulonephritis

AIM: To investigate the correlation of different hepatitis B virus gene mutations with the development of hepatitis B virus-associated glomerulonephritis (HBV-GN).

METHODS: Nineteen HBV-GN patients and 22 chronic hepatitis B (CHB) patients were included in the study. Gene mutations in the core gene coding region and core promoter/precore region of HBV were detected by complete genome sequencing.

RESULTS: In the core promoter/precore region, the prevalences of the nt 1727 and nt 1773 mutations were significantly higher in HBV-GN patients than in CHB patients (100% vs 50.0% and 47.4% vs 13.6%, respectively; both P < 0.05). No significant differences were noted in the prevalences of the nt 1762/1764 mutations between the two groups of patients (P > 0.05). In the core gene coding region, the prevalence of the nt 2011 mutation was significantly lower in HBV-GN patients than in CHB patients (10.5% vs 40.9%, P < 0.05). No significant differences were noted in the prevalences of the nt 2005, nt 2201, nt 2245 and nt 2290 mutations between the two groups of patients (P > 0.05).

CONCLUSION: Some hepatitis B virus gene mutations may be correlated with the development of HBV-GN.

Specific mutations in the enhancer II/core promoter/precore regions of hepatitis B virus subgenotype C2 in Korean patients with hepatocellular carcinoma

Recently, hepatitis B virus (HBV) genotypes and mutations have been reported to be related to hepatocellular carcinoma (HCC). This cross-sectional case-control study examined the relationship between HCC and mutations in the enhancer II/core promoter and precore regions of HBV by comparing 135 Korean HCC patients infected with HBV genotype C2 (HBV/C2; HCC group) with 135 age-, sex-, and hepatitis B e antigen (HBeAg) status-matched patients without HCC (non- HCC group). Age and sex were also matched between HBeAg-positive and -negative patients. The prevalence of T1653, A1689, V1753, T1762/A1764, T1846, A1850, C1858, and A1896 mutations was evaluated in this population. The prevalence of the T1653 mutation in the box alpha region, the T1689 [corrected] mutation in between the box alpha and beta regions, and the T1762/A1764 mutations in the basal core promoter region was significantly higher in the HCC group compared to the non-HCC group (8.9% vs. 2.2%, P = 0.017; 19.3% vs. 4.4%, P < 0.001; and 60.7% vs. 22.2%; P < 0.001). Among HBeAg-negative patients, the frequency of the T1653 mutation was higher in the HCC group. Regardless of HBeAg status, the prevalence of the T1689, [corrected] and T1762/A1764 mutations was higher in the HCC group than in the non-HCC group. However, no association was observed between mutations in the precore region and HCC. Upon multivariate analysis, the presence of the T1653, T1689, [corrected] and T1762/A1764 mutations was an independent predictive factor for HCC. The addition of the T1653 or T1689 [corrected] mutation to T1762/A1764 increased the risk of HCC. In conclusion, the T1653, T1689, [corrected] and/or T1762/A1764 mutations were associated with the development of HCC in Korean patients infected with HBV/C2.

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.

A population-based study to investigate host genetic factors associated with hepatitis B infection and pathogenesis in the Chinese population

Background

Hepatitis B virus (HBV) infection is a significant public health problem that may lead to chronic liver disease, cirrhosis, and hepatocellular carcinoma (HCC). Approximately 30% of the world's population has been infected with HBV and approximately 350 million (5–6%) are persistent carriers. More than 120 million Chinese are infected with HBV. The role of host genetic factors and their interactions with environmental factors leading to chronic HBV infection and its complications are not well understood. We believe that a better understanding of these factors and interactions will lead to more effective diagnostic and therapeutic options.

Methods/Design

This is a population-based, case-control study protocol to enroll 2200 Han Chinese from medical centers in northern and western China. Adult subjects in the following groups are being enrolled: healthy donors (n = 200), HBV infected persons achieving virus clearance (n = 400), asymptomatic HBV persistent carriers (n = 400), chronic hepatitis B cases (n = 400), decompensated liver cirrhosis with HBV infection cases (n = 400), and hepatocellular carcinoma with HBV infection cases (n = 400). In addition, for haplotype inference and quality control of sample handling and genotyping results, children of 1000 cases will be asked to provide a buccal sample for DNA extraction. With the exception of adult patients presenting with liver cirrhosis or HCC, all other cases and controls will be 40 years or older at enrollment. A questionnaire is being administered to capture dietary and environmental risk factors. Both candidate-gene and genome-wide association approaches will be used to assess the role of single genetic factors and higher order interactions with other genetic or environmental factors in HBV diseases.

Conclusion

This study is designed and powered to detect single gene effects as well as gene-gene and environmental-gene interactions. The identification of allelic polymorphisms in genes involved in the pathway leading to chronic viral infection, liver cirrhosis and, ultimately, hepatocellular carcinoma would provide insights to those factors leading to HBV replication, liver inflammation, fibrosis, and the carcinogenic process. An understanding of the contribution of host genetic factors and their interactions may inform public health policy, improve diagnostics and clinical management, and provide targets for drug development.

Influence of hepatitis B virus X and core promoter mutations on hepatocellular carcinoma among patients infected with subgenotype C2

Hepatitis B virus (HBV) genotypes/subgenotypes and their related mutations in the HBV genome have been reported to be associated with hepatocellular carcinoma (HCC). To determine the HCC-associated mutations of the HBV genome in the entire X, core promoter, and precore/core regions, a cross-sectional control study was conducted comparing 80 Japanese patients infected with HBV C2 and suffering from HCC with 80 age-, sex-, and hepatitis B e antigen (HBeAg) status-matched patients without HCC (non-HCC group). Each HBeAg-positive group (31 with HCC; 29 without HCC) and HBeAg-negative group (49 with HCC; 51 without HCC) was also matched with respect to age and sex. The C1479, T1485, H1499, A1613, T1653, V1753, T1762/A1764, and A1896 mutations were frequent in this population. The prevalences of the T1653 mutation in the box alpha region and the V1753 and T1762/A1764 mutations in the basal core promoter region were significantly higher in the HCC group than in the non-HCC group (56% versus 30%, 50% versus 24%, and 91% versus 73% [P = 0.0013, P = 0.0010, and P = 0.0035, respectively]). The platelet count was significantly lower for the HCC group than for the non-HCC group (10.7 x 10(4) +/- 5.1 x 10(4) versus 17.3 x 10(4) +/- 5.1 x 10(4) platelets/mm(3) [P < 0.0001]). Regardless of HBeAg status, the prevalence of the T1653 mutation was higher in the HCC group (52% versus 24% [P = 0.036] for HBeAg-positive patients and 59% versus 33% [P = 0.029] for HBeAg-negative patients). In the multivariate analysis, the presence of T1653, the presence of V1753, and a platelet count of < or =10 x 10(4)/mm(3) were independent predictive factors for HCC (odds ratios [95% confidence intervals], 4.37 [1.53 to 12.48], 7.98 [2.54 to 25.10], and 24.39 [8.11 to 73.33], respectively). Regardless of HBeAg status, the T1653 mutation increases the risk of HCC in Japanese patients with HBV/C2.

Factors associated with fulminant liver failure during an outbreak among injection drug users with acute hepatitis B

Death related to acute hepatitis B occurs in approximately 1% of patients. We investigated an outbreak of hepatitis B virus (HBV) infections among injection drug users (IDUs) resulting in several deaths. We conducted a case-control study of fulminant (case patients) and nonfulminant (control patients) HBV infections. We directly sequenced the entire HBV genome from fulminant and nonfulminant cases. From October 1998 to July 2000, 21 acute HBV infections, including 10 fulminant hepatitis B cases, were identified. The median age was 30 (range, 18-49) years, 12 (57%) were female, 20 (95%) were American Indians, and 20 (95%) reported injecting illicit drugs. All patients with fulminant hepatitis B died (case-fatality rate = 47.6%). Case patients (n = 5) and control patients (n = 9) were similar with respect to age, sex, race, and hepatitis C virus serostatus. All case patients used acetaminophen during their illness compared with 44% of control patients (P =.08). Compared with control patients, case patients lost more weight in the 6 months before illness (P =.04); during their illness, they used more alcohol (P =.03) and methamphetamine (P =.04). All 9 isolates sequenced were genotype D, shared 99.7% homology, and included mutations previously described in association with fulminant hepatitis B. In conclusion, a high prevalence of exposure to factors potentiating hepatic damage with acute hepatitis B contributed to the outbreak's high mortality rate; mutations present in the outbreak strain might also have been a factor. Improved vaccination coverage among IDUs has the potential to prevent similar outbreaks in the future.

Precore and core promoter mutations, hepatitis B virus DNA levels and progressive liver injury in chronic hepatitis B

BACKGROUND/AIMS

To elucidate the viral factors responsible for progressive liver injury in chronic hepatitis B.

METHODS

We analyzed 179 persistently infected patients (21 asymptomatic carriers, 126 with chronic hepatitis and 32 with cirrhosis) with genotype C hepatitis B virus (HBV). HBeAg/anti-HBe, levels of HBV DNA, mutations in the basic core promoter (BCP) region at nucleotides 1762/1764 and mutation in the precore (preC) region at nucleotide 1896 were determined. Serial samples from 18 patients also were analyzed.

RESULTS

HBeAg/anti-HBe and HBV DNA levels per se were not related to liver fibrosis. The frequency of BCP mutations increased with progression of liver fibrosis. Although the preC mutation was detected more often among the LC group, the role of this mutation in progression of fibrosis seems less than that of the BCP mutations. Sequential analysis showed that (1) rapidly progressing cases were positive continuously for double mutations in the BCP with a wild-type precore sequence, and (2) asymptomatic cases with anti-HBe acquired the preC mutation during their clinical course.

CONCLUSIONS

Double mutations in the BCP region at nucleotide 1762/1764 are closely related to progression of chronic liver disease. Acquisition of mutation in the preC region at nucleotide 1896 may contribute to inactivation of chronic liver disease.

Molecular, immunological and clinical properties of mutated hepatitis B viruses

Hepatitis B virus (HBV) is at the origin of severe liver diseases like chronic active hepatitis, liver cirrhosis and hepatocellular carcinoma. There are some groups of patients with high risk of generation of HBV mutants: infected infants, immunosuppressed individuals (including hemodialysis patients), patients treated with interferon and lamivudine for chronic HBV infection. These groups are the target for molecular investigations reviewed in this paper. The emergence of lamivudine- or other antiviral-resistant variants, rises concern regarding long term use of these drugs. Infection or immunization with one HBV subtype confers immunity to all subtypes. However, reinfection or reactivation of latent HBV infection with HBV mutants have been reported in patients undergoing transplant and those infected with HIV. Mutations of the viral genome which are not replicative incompetent can be selected in further course of infection or under prolonged antiviral treatment and might maintain the liver disease. Four open reading frames (ORF) which are called S-gene, C-gene, X-gene and P-gene were identified within the HBV genome. Mutations may affect each of the ORFs. Mutated S-genes were described to be responsible for HBV-infections in successfully vaccinated persons, mutated C-genes were found to provoke severe chronic liver diseases, mutated X-genes could cause serious medical problems in blood donors by escaping the conventional test systems and mutated P-genes were considered to be the reason for chemotherapeutic drug resistance. This paper reviews molecular, immunological and clinical aspects of the HBV mutants.

Molecular analysis of hepatitis B virus genomes isolated from black African patients with fulminant hepatitis B

To investigate further the possible role of mutant hepatitis B viruses in the pathogenesis of fulminant hepatitis B, the genomic sequence of hepatitis B virus isolates from 9 South African blacks with this disease, including 5 entire genomes, was analysed. Seven of the isolates were genotype A. The mutation most often reported in patients with fulminant hepatitis B, the G1896A precore stop-codon substitution, was, as expected, not present in the genotype A isolates with the exception of one in which it was accompanied by a compensatory C1858T substitution. G1896A was, however, present in the one genotype D isolate. No other precore-defective mutants were detected. The other mutation commonly found in patients with fulminant hepatitis B, the paired A1762T, G1764A substitution in the basic core promoter, was present in only one patient and G1764A in one other. The pre-surface initiation-codon mutation documented in a number of patients with fulminant hepatitis B was not found in our isolates. An 18-amino acid deletion present in the pre-surface region of one isolate has not previously been described in fulminant hepatitis B. Variations within the surface region were mainly genotype specific and not previously described. A relatively large number of mutations were present in the middle region of the core gene in those isolates without G1896A or A1762T, G1764A mutations, although the pattern was not consistent with those in published studies. Thus, as in other published series in which the entire genome of hepatitis B virus responsible for fulminant hepatitis was sequenced, we detected many mutations in different genes, but none was common to all the reported isolates.

Prevalence of HBV core promoter/precore/core mutations in Gambian chronic carriers

One hundred forty-two precore/core sequences were obtained from Gambian chronic hepatitis B virus (HBV) carriers and the predominant variants defined. The two point mutations, from A to T and G to A at nt positions 1762 and 1764 in the basic core promoter region, were found in only 7/99 (7%) of the samples where this region was sequenced. These mutations were found in both HBeAg-positive and -negative patients. The precore stop-codon mutation at nt position 1896 was found in 14/51 (27%) of HBeAg-negative samples, which is a lower prevalence rate in comparison with other parts of the world with high carrier rates. In HBeAg-positive patients the core amino acid sequences were conserved, but after seroconversion to anti-HBe significantly more changes were apparent. Several of the amino acid substitutions found have been described previously been in wild-type viruses of other genotypes.

Effect of multiple mutations in the core promoter and pre-core/core region of hepatitis B virus genome on the response to interferon in e antigen-positive chronic hepatitis B

BACKGROUND AND AIMS

Hepatitis B virus (HBV) genomic mutations may be one of the factors that influence the efficacy of interferon (IFN) therapy. The aim of this study was to investigate the effects of mutations in different parts of the HBV genome on IFN therapy.

METHODS

We studied the baseline clinical, biochemical, serologic and virologic parameters in 17 patients with e antigen-positive chronic hepatitis B. The DNA sequence of the X gene and pre-core/core gene in serum samples of these patients was analyzed before the initiation of IFN therapy.

RESULTS

All five patients with the T1762-A1764 mutation were IFN responsive, while among the 12 remaining patients, only two responded to therapy. Among five patients with both a pre-core A1896 mutation and a mutation in the epitope aa 107-118 of the core region, four were non-responders whereas the fifth responded to therapy. In three other patients with A1896 mutations, one with simultaneous mutations in five lymphocytic epitopes did not respond to therapy; the two remaining patients with concomitant mutations in one or two epitopes were responsive. Serum HBV-DNA levels were lower and titers of antibody to hepatitis B virus core antigen-immunoglobin M (anti-HBc-IgM) were higher in the responders than in the non-responders. Hepatitis B virus genotypes B and C were found to be in all these Chinese patients.

CONCLUSIONS

These results suggest that HBV genomic mutations, serum viral loads and titers of anti-HBc-IgM might be predictive of the efficacy of IFN therapy. These clinical findings should be further investigated by in vivo and in vitro experiments.

Hepatitis B virus X gene variability in French-born patients with chronic hepatitis and hepatocellular carcinoma

The polymorphism of the hepatitis B virus (HBV) X gene from patients born in Lorraine has been studied in serum samples from 22 HBV infected patients, 14 presenting with chronic hepatitis and 8 with hepatocellular carcinoma (HCC). Subtypes adw and ayw represented 21 of the 22 sequenced isolates. The sequence of the X gene of HBV strains from these patients differed from the ones of Far East origin by A to T(1678) and G to A(1759) changes for subtype ayw and C to T(1792) for adw. The expression of the preC region, as indicated by the detection of HBe antigen (HBeAg), was not observed in 11 patients. In 6 patients (3 HCC and 3 non HCC), the absence of HBeAg could be related to a stop codon at position 28. For the 5 remaining patients, the precore stop mutation at codon 28 was not evidenced but 3 out these 5 patients had mutations at nt 1764 and nt 1766 in the promoter of the preC/C gene. These two mutations were also observed in 2 patients with HBeAg, indicating that they are not implicated in the suppression of expression of this gene. Independently of the serotype, two main differences were noted between aminoacid (aa) sequences of chronic hepatitis and HCC related strains: first, twice as many aa changes were found in HCC patients than in chronic hepatitis B carriers (mean of aa changes per patient 4.1 vs. 2.0) and second, we found apparition of polar aa in HCC patients. Most mutations already described in patients from the Far East with HCC have been found in strains of patients from Lorraine. The changes K130M and V131I, considered as "hot spot mutations," were found in strains of HCC patients carrying an ayw subtype of the HBV genome but not in the ones of chronically infected patients. In contrast, strains of the adw subtype had these two changes in the two groups of patients. However when considering the 22 sequenced genes, these hot spot mutations were associated with HCC (P = 0.034).

Molecular epidemiology of an outbreak of fulminant hepatitis B

A nosocomial outbreak of hepatitis B occurred among the inpatients of a hematology unit. Nine of the 11 infected patients died from fulminant hepatitis. An investigation was conducted to identify the source of infection and the route of transmission. Two clusters of nosocomial hepatitis B were identified. The hepatitis B virus (HBV) genome from serum samples of all case patients, of one HBsAg-positive patient with acute reactivation of the infection, and of eight acutely infected, unrelated cases was identified by PCR amplification of viral DNA and was entirely sequenced. Transmission was probably associated with breaks in infection control practices, which occurred as single events from common sources or through a patient-to-patient route, likely the result of shared medications or supplies. Sequence analysis evidenced close homology among the strains from the case patients and that from the patient with reactivation, who was the likely source of infection. Molecular analysis of viral isolates evidenced an accumulation of mutations in the core promoter/precore region, as well as several nucleotide substitutions throughout the genome. The sequences of all patients were compared with published sequences from fulminant and nonfulminant HBV infections.

The core promoter of hepatitis B virus

The core promoter (CP) of hepatitis B virus (HBV) plays a central role in HBV replication and morphogenesis, directing the transcription of both species of 3.5 kb mRNA: pregenomic (pg) RNA and precore (pre-C) mRNA. The CP overlaps the 3' end of the X open-reading frame (ORF) and the 5' end of the pre-C/C ORF. The major functional elements of the CP are the upper regulatory region (URR) and the basic core promoter (BCP). The BCP is sufficient for accurate initiation of both pre-C mRNA and pgRNA transcription. It contains four AT-rich regions and the initiators for pre-C mRNA and pgRNA transcription. The upstream regulatory region consists of the negative regulatory element and the core upstream regulatory sequence. Co-operative interaction of various liver-enriched and ubiquitous transcription factors is necessary for liver-specific expression from the CP. These factors bind to the CP. Sequence conservation within the CP is crucial for maintaining active viral replication, and variation may contribute to the persistence of HBV within the host, leading to chronic infection and, ultimately, hepatocarcinogenesis. The most frequently described mutations within this region are an A to T transversion at position 1762 together with a G to A transition at position 1764. This double mutant is accompanied by a reduced level of hepatitis B e antigen (HBeAg) expression. Deletions, insertions and duplications occur within the CP.

T1762/A1764 variants of the basal core promoter of hepatitis B virus; serological and clinical correlations in Chinese patients

BACKGROUND

A double variant in the basal core promoter, converting nucleotide 1762 from A to T (T1762) and nucleotide 1764 from G to A (A[764), has been described in patients with chronic hepatitis B infection. Its prevalence and significance in Chinese chronic HBV carriers are unknown.

METHODS

We studied 177 Chinese patients with chronic HBV infection (chronic hepatitis/asymptomatic: 89/88; hepatitis B e antigen positive/negative: 84/93). The double variant was detected by mismatched polymerase chain reaction and restriction fragment length polymorphism analysis. The reliability of this method was verified by sequencing in 41 serum samples with 100% matching.

RESULTS

The double variant T1762/ A1764 was found in 52 of 89 patients with chronic hepatitis, but in only 6 of 59 asymptomatic carriers (p<0.001). The prevalence was significantly lower in hepatitis B e antigen positive patients (23/84) than in hepatitis B e antigen negative patients (35/64) (p<0.005). Precore variant, A1896 was detected in 40 individuals; 31 of them suffered from chronic hepatitis and 9 were asymptomatic (p<0.001). A combination of both variants T1762/A1764 and A1896 was seen in 3 of 59 asymptomatic and 22 of 89 patients with chronic hepatitis (p<0.005).

CONCLUSIONS

Mismatched polymerase chain reaction with restriction fragment length polymorphism provides a reliable, easy and fast method for detection of the presence of the T1762/A1764 variant. In Chinese chronic hepatitis B carriers, T1762/A1764 variant was associated with both active liver disease and hepatitis B e antigen negativity.

Three cases of severe subfulminant hepatitis in heart-transplanted patients after nosocomial transmission of a mutant hepatitis B virus

Fulminant and severe viral hepatitis are frequently associated with mutant hepatitis B virus (HBV) strains. In this study, the genetic background of a viral strain causing severe subfulminant outcome in heart-transplanted patients was studied and compared with viral hepatitis B strains that were not linked to severe liver disease in the same setting. A total of 46 patients infected nosocomially with HBV genotype A were studied. Five different viral strains were detected, infecting 3, 9, 5, 24, and 5 patients, respectively. Only one viral strain was found to be associated with the subfulminant outcome and 3 patient deaths as a consequence of severe liver disease. The remaining 43 patients with posttransplantation HBV infection did not show this fatal outcome. Instead, symptoms of hepatitis were generally mild or clinically undiagnosed. Comparison of this virus genome with the four other strains showed an accumulation of mutations in the basic core promoter, a region that influences viral replication, but also in hepatitis B X protein (HBX) (7 mutant motifs), core (10 mutant motifs), the preS1 region (5 mutant motifs), and the HBpolymerase open reading frame (17 motifs). Some of these variations, such as those in the core region, were located on the tip of the protruding spike of the viral capsid (codons 60 to 90), also known in part as an important HLA class II-restricted epitope region. These mutations might therefore influence the immune-mediated response. The viral strain causing subfulminant hepatitis was, in addition, the only strain with a preCore stop codon mutation and, thus, hepatitis B e antigen (HBeAg) expression was never observed. The combination of these specific viral factors is thought to be responsible for the fatal outcome in these immune-suppressed heart-transplant recipients.

High prevalence of 1762(T) 1764(A) mutations in the basic core promoter of hepatitis B virus isolated from black Africans with hepatocellular carcinoma compared with asymptomatic carriers

The purpose of this study was to identify mutations in the basic core promoter and enhancer II region of the hepatitis B virus (HBV) that might cause the HBV e antigen (HBeAg)-negative phenotype and contribute to hepatocarcinogenesis in black African carriers of the virus. The basic core promoter/enhancer II overlaps with the X gene. HBV DNA from serum of 47 asymptomatic carriers and 50 patients with hepatocellular carcinoma and from 28 tumor and 10 nontumor liver tissues was amplified and sequenced directly. That part of the enhancer II region not overlapping the basic core promoter was completely conserved in all samples. Missense mutations at nucleotides 1809 and 1812 in the basic core promoter were found in 80% of all sequences and may represent wild-type sequence in Southern African isolates. Nucleotide and amino acid divergences were higher in the basic core promoter of hepatocellular carcinoma patients when compared with asymptomatic carriers (P <.0001). This applied particularly to the paired 1762 adenine to thymine (1762(T)) and 1764 guanine to adenine (1764(A)) missense mutations, the prevalence of which was 66% in patients with hepatocellular carcinoma compared with 11% in asymptomatic carriers (P <.0001). There was no association between the presence of 1762(T) 1764(A) and HBeAg negativity, although these mutations suppressed HBeAg titers in HBeAg-positive patients. Suppression of HBeAg expression as well as alteration of the amino acid sequence of the X protein may play a role in hepatocarcinogenesis.

Expression of mutated hepatitis B virus X genes in human hepatocellular carcinomas

To explore the role of hepatitis B virus (HBV) X protein in liver carcinogenesis, independently from its role in viral replication, we have analyzed X gene structure and expression in tumorous and non-tumorous tissues obtained from 9 hepatitis B surface antigen (HBsAg)-negative, HBV DNA-positive patients. HBV replication was undetectable in tumorous tissues. HBV X gene was truncated at its 3' end in 5 of 9 tumorous tissues and 1 of 8 non-tumorous livers. Sequence analysis performed on uninterrupted X genes from 3 tumors and 3 surrounding non-tumorous tissues showed a high rate of mutations, selectively in the tumorous livers. In 1 of the 3 tumors, a frameshift mutation induced a new stop at codon 129. HBV RNAs were tested by reverse transcriptase-polymerase chain reaction (RT-PCR) with surface (S), core (C) and X specific primers. X, but not S and C, RNA expression was found in 6 of 8 tumors and in 6 of 7 non-tumorous tissues. This finding was consistent with immunohistochemical detection of X, but not S and C, antigens in all tumors also expressing X RNA. Our results provide evidence for selective expression of HBV X, but not S and C, RNA and protein in the tumorous and non-tumorous tissue of HBsAg-negative, HBV DNA-positive patients. It also shows that the structure of the X gene is modified (interrupted or highly mutated) in the majority of tumorous livers. Taken together, our findings are consistent with a potential role of mutated X proteins in HBV-related liver oncogenesis.

Functional analysis of HBV genomes from patients with fulminant hepatitis

Two previous case reports suggest that hepatitis B virus (HBV) core promoter variants with a high replication competence contribute to the pathogenesis of fulminant hepatitis B (FHB). We recently found in HBV genomes from patients with FHB an accumulation of mutations within the core promoter region. Therefore, the aim of this study was to investigate the phenotype of these HBV variants. Replication competence and expression of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) of viral genomes from seven patients with FHB and one patient with fulminant recurrent hepatitis after liver transplantation were analyzed by transfection experiments in human hepatoma cells. Compared with wild-type virus, the HBV variants from the seven patients with FHB produced similar or slightly lower levels of intracellular replicative intermediates and extracellular viral particles. In contrast, the HBV genomes from the patient with fulminant recurrent hepatitis synthesized and secreted significantly more HBV DNA. All genomes tested expressed similar or even higher levels of HBeAg compared with wild-type virus, except for those from four patients with a precore stop codon mutation in the respective dominant viral populations. The level of HBsAg produced by all variant genomes was similar or reduced compared with wild-type virus. These data indicate that in some cases HBV variants with enhanced replication competence and/or a defect in HBeAg expression may contribute to the development of FHB. However, neither phenotype is an essential prerequisite; thus, an additional role of other viral or host factors in the pathogenesis of FHB is suggested.

Molecular biology of hepatitis B virus e antigen

Hepatitis B virus (HBV) e antigen (HBeAg) was discovered in 1972 as one of the serological markers of HBV infection. Although 25 years have passed since its initial discovery, the function of this antigen in the life cycle of HBV has remained elusive. Mutations in the HBV genome that prevent the expression of HBeAg do not abolish the replication of HBV, indicating that this antigen is not essential for HBV replication. In contrast, the conservation of the HBeAg gene in the genomes of related animal viruses, including the distantly related duck HBV, argues for an important function of this antigen. The purpose of the present article is to review the molecular biology of HBeAg and to examine its possible functions in the life cycle of HBV.

Mutations of the X region of hepatitis B virus and their clinical implications

Nucleotide (nt) sequences of the X region of more than 130 hepatitis B virus (HBV) isolates were determined and derived from patients with a variety of clinical features. Correlation of nt substitutions with clinicopathological characteristics was attempted. The X region (465nt) is crucial for the replication and expression of HBV because the X protein transactivates the HBV genes and this region contains the core promoter, enhancer II, and two direct repeats. There are several mutational hotspots, some of which seem to relate to immunological epitopes of the X protein. Two kinds of mutations which have important clinical significances were found. One is an 8-nt deletion between nt 1770 and 1777, which truncates 20 amino acids from the carboxyl terminus of the X protein. This deletion leads to the suppression of replication and expression of HBV DNA, resulting in immunoserological marker (HBsAg) negativity. This silent HBV infection is responsible for the majority of non-A to non-E hepatitis. The other mutation substituting T for C (nt 1655), T for A (nt 1764) and A for G (nt 1766) seems to relate to fulminant hepatitis. Further sequencing studies and in vitro mutagenesis experiments will clarify the significance of other mutations of the X region.

Type, prevalence, and significance of core promoter/enhancer II mutations in hepatitis B viruses from immunosuppressed patients with severe liver disease

Little is known about the functional significance of hepatitis B virus (HBV) sequence heterogeneity. Here we analyzed the type, frequency, and function of mutations in the core promoter/enhancer II region of HBV in immunosuppressed patients. The major HBV population in immunosuppressed patients with severe liver disease had deletions, insertions, and/or base changes in this region. Such mutations were not found in immunosuppressed patients with mild disease. Except for two mutations, all created a hepatocyte nuclear factor 1 (HNF1) binding site or a potential HNF3 binding site. Occasionally, known binding sites for C/EBP and HNF4 were additionally duplicated. Eleven mutated core promoter prototype sequences were functionally tested in the context of a wild-type genome by transfection in Huh7 cells. Despite the diversity of mutations tested, all decreased steady-state levels of pre-C mRNA drastically and increased those of the C mRNA/ pregenomic RNA. This correlated with reduced levels of secreted hepatitis B e antigen and increased intracellular levels of core and Pol proteins and replicative HBV DNA intermediates. The levels of secreted HBV DNA-containing particles were also increased although most of the mutations reduced the levels of pre-S/S mRNA and pre-S1, and pre-S2 proteins as well as secretion of hepatitis B surface antigen. These data reveal a novel class of HBV variants with HNF1 binding sites in the core promoter which are characterized by a defect in hepatitis B e antigen expression, enhanced replication, and altered protein levels, all probably mediated by altered transcription factor binding. The phenotype of these variants and their prevalence only in immunosuppressed patients with severe liver disease may indicate that they play a role in pathogenesis.