Effects of a naturally occurring mutation in the hepatitis B virus basal core promoter on precore gene expression and viral replication

Comparative study of genotype B and C hepatitis B virus-induced chronic hepatitis in relation to the basic core promoter and precore mutations

BACKGROUND

The clinicopathological profiles and outcome of chronic hepatitis B can differ by hepatitis B virus (HBV) genotypes. In Japan, genotype B and C are two major HBV genotypes. The basic core promoter and precore mutations are other known viral factors for disease activity, although the relationship between HBV genotypes and these mutations is not fully understood.

METHODS

The HBV genotypes in 90 patients with chronic hepatitis B were determined using an ELISA. Obtained data were correlated with clinicopathological parameters, basic core promoter, precore and the nucleotide 1858 mutations of the HBV genome.

RESULTS

Among 90 cases, 20 (22.2%) had genotype B and 70 (77.8%) had genotype C HBV. Genotype B patients were older than genotype C patients (44.0 +/- 13.9 vs 34.7 +/- 11.0 P = 0.0022). The HBeAg was more prevalent in genotype C than B patients (P = 0.0008) while anti-HBe was more common in genotype B than C patients (P = 0.0002). Serum aspartate aspartate aminotransferase/alanine aminotransferase levels (B: 220.7 +/- 612.8/257.0 +/- 498.0 IU/L vs C: 111.3 +/- 122.8/201.6 +/- 229.4 IU/L, P = 0.16/0.48) and HBV viral loads in blood (B: 6.1 +/- 3.1 log genome equivalent [LGE]/mL vs C: 6.7 +/- 2.3 LGE/mL, P = 0.42) were equivalent. The seroconversion from HBeAg to anti-HBe occurred significantly earlier in genotype B than C patients (62 +/- 53 months vs 136 +/- 54 months, P = 0.0028) during the mean observation period of 149 +/- 82 months even under various therapeutic modalities. The categories III and IV of the histological activity index in genotype C were higher (III: P < 0.005, IV: P < 0.05, n = 68) than that in B patients whereas category II was higher in genotype B than C patients (P < 0.05). The double mutation (1762T/1764A) in the basic core promoter was more frequently found in genotype C than in B HBV (P = 0.0068), whereas the precore mutation (1896A) was more common in genotype B than C HBV (P = 0.0233). The incidence of 1858C that was complementary to the precore mutation site in the stem-loop structure in, was equally rare in both genotype B and C HBV.

CONCLUSIONS

Genotype B patients were older, had earlier HBeAg seroconversion and exhibited more severe lobular necroinflammation, less portal inflammation and fibrosis than genotype C patients. This genotypic difference is related to the basic core promoter and precore mutations irrespective of 1858C. (c) 2004 Blackwell Publishing Asia Pty Ltd.

Low frequency of mutations in the X gene, core promoter and precore region of hepatitis B virus infected Vietnamese

Numerous mutations in the hepatitis B virus (HBV) genome have been described, but in most cases their role in the pathogenesis of HBV infection is still unclear. Therefore, we analysed specific mutations in HBV-infected Vietnamese patients and assessed their potential relationship with their clinical outcome. A total of 153 HBV-infected Vietnamese patients with well-characterised clinical profiles were enrolled. None of the study participants had a history of alcohol or drug use and none received any antiviral or immunosuppressive therapy before or during the course of this study. The HBx- and core promoter regions were analysed by sequencing. The majority of isolates corresponded to genotype A. The presence of hepatitis B e antigen (HBeAg) was associated with significantly higher viral loads in the chronic HBV-infection group (P = 0.026). Double mutations in the core promoter (1762/1764) were more frequent in those with cancer than in noncancer patients (P < 0.01). Mutations at nucleotide (nt) 1766/1773 were found at low prevalence but with no obvious association to clinical presentation. Cytosine at nt 1858 was predominant but the stop codon mutation in the precore region was not detected. In the study, 4/48 hepatocellular carcinoma (HCC) patients revealed truncated HBx, whilst the serine to alanine mutation (codon 31) of HBx was more prevalent in cancer patients than in asymptomatic HBV carriers (P < 0.01). Thus, the low frequency of mutations indicates the relation of the absence of antiviral pressure in this population. The exclusively found prevalence of certain mutations detected in those with HBV-related carcinoma nevertheless indicates a degree of association with disease progression.

Hot-spot mutations in hepatitis B virus core gene: eliciting or evading immune clearance?

The biological implications of substitutions L60V and I97L in the core (c) gene of hepatitis B virus (HBV) were investigated in order to determine whether they could change the immunogenicity of HBcAg or influence the immune response in mice. Three strains of recombinant adenoviruses--AdHBV-WT, AdHBV-L60V and AdHBV-I97L--containing wild-type or mutant HBV genomes were constructed using the AdEasy system and used to infect BALB/c mice intranasally. Infected mice produced anti-HBc efficiently to comparable levels. IgG1 and IgG2a specific for HBcAg were present in mice sera, and the response was dominated by IgG2a. The lymphocyte proliferative response specific for HBcAg was assessed by [3H]-thymidine uptake. We found that AdHBV-WT induced a stronger T-cell proliferation response than AdHBV-L60V and AdHBV-I97L. In conclusion, the L60V and I97L substitutions had no influence on humoral immune responses, but could downregulate T-cell responses to HBcAg, suggesting that L60V and I97L were immune escape mutants.

Effect of mutating the two cysteines required for HBe antigenicity on hepatitis B virus DNA replication and virion secretion

Hepatitis B virus (HBV) variants with impaired expression of e antigen (HBeAg) frequently arise at the chronic stage of infection, as exemplified by precore and core promoter mutants. Since an intramolecular disulfide bond maintains the secondary structure of HBeAg, we explored effect of missense mutations of either cysteine codon. Consistent with earlier reports, substitution of each cysteine rendered HBeAg nearly undetectable. With underlying nucleotide changes at the loop of pregenome encapsidation signal, the C-7 mutants were severely impaired in pregenomic RNA packaging and hence DNA replication. Although none of the missense mutations at C61 reduced DNA replication, replacement with arginine, but not alanine, aspartic acid, phenylalanine, or serine, blocked virion secretion. Consistent with the detection of C61R genome from a patient serum, secretion block of the C61R mutant could be overcome by co-expression of wild-type core protein. In conclusion, point mutations of the C61 codon may generate viable HBeAg-negative variants.

Hepatitis B virus mutations associated with fulminant hepatitis induce apoptosis in primary Tupaia hepatocytes

Hepatitis B virus (HBV) core promoter mutations have been implicated in the pathogenesis of fulminant hepatitis B. Due to the limited availability of primary human hepatocytes, the functional characterization of HBV mutants has been performed predominantly in transformed cells, which may not represent ideal model systems for studying virus-cell interactions. We and others have shown that primary hepatocytes of the tree shrew Tupaia belangeri support HBV infection and replication. In this study, we used primary Tupaia hepatocytes to analyze the phenotype of two HBV core promoter mutations that have been associated with a clinical outbreak of fatal fulminant hepatitis. Similar to previous findings in human hepatoma cells, the HBV core promoter mutations resulted in enhanced viral replication and core expression. Surprisingly, however, the presence of the mutations had a marked effect on hepatocyte viability not previously observed in hepatoma cells. Reduced cell viability was found to be due to the induction of apoptosis, as evidenced by caspase-3 activation and nuclear fragmentation. In conclusion, HBV mutants exhibit a novel phenotype in primary hepatocytes distinctly different from previous findings in hepatoma cell lines. This phenotype may have important implications for the understanding of the fulminant clinical course associated with HBV mutations.

Genotype characterization and phylogenetic analysis of hepatitis B virus isolates from Iranian patients

Hepatitis B virus (HBV) is one of the major causative agents of acute and chronic liver disease worldwide and is believed to be responsible for a million deaths annually. Eight genotypes of HBV, A to H, have been described on the basis of similarity of the complete genomes sequence. Although, it is reported that the predominant HBV genotype in the Mediterranean area and the middle east is genotype D, there are no reports on HBV genotypes prevalent in Iran. In this study, the C and S regions of HBV from 26 chronic hepatitis B Iranian patients were amplified and sequenced. Phylogenetic analysis revealed that all Iranian HBV isolates sequences were classified into genotype D with bootstrap values of 100%, 73%, and 100% (1,000 replicates each) for S, C, and preS2 regions, respectively. The mean percent intra-distance of S and C regions were 0.8% and 2.3%, respectively. The mean percent inter-distance of S and C regions between Iranians and genotype D isolates were 1.7% and 3.0%, respectively, and the range of mean percent nucleotide distance of S and C regions between Iranians and the other reference isolates were 7.9%-17.5% and 4.8%-14.7%, respectively. Thirteen out of 23 HBV C region sequences showed nucleotide "A" at position 1896 (precore mutant) in C region. Nucleotide 1858 showed presence of "T" in all isolates. No insertion or deletion was found in both regions. SimPlot and BootScanning analyses did not show any recombination between Iranian isolates and other genotypes in both regions.

Epidemiology and Prevention of Hepatitis B Virus Infection

Hepatitis B is one of the most common infectious diseases globally. It has been estimated that there are 350 million chronic hepatitis B virus (HBV) carriers worldwide. The prevalence of chronic HBV infection varies geographically, from high (>8%), intermediate (2-7%) to low (<2%) prevalence. HBeAg-negative chronic hepatitis B (e-CHB) and occult HBV infection are two special clinical entities, and the prevalence and clinical implications remain to be explored. The predominant routes of transmission vary according to the endemicity of the HBV infection. In areas with high HBV endemicity, perinatal transmission is the main route of transmission, whereas in areas with low HBV endemicity, sexual contact amongst high-risk adults is the predominant route. HBV has been classified into 7 genotypes, i.e. A to G, based on the divergence of entire genome sequence and HBV genotypes have distinct geographical distributions. Three main strategies have been approved to be effective in preventing HBV infection. They are behavior modification, passive immunoprophylaxis, and active immunization. The implement of mass HBV immunization program is recommended by the WHO since 1991, and has dramatically decreased the prevalence of HBV infection and HCC in many countries.

Patients with and without loss of hepatitis B virus DNA after hepatitis B e antigen seroconversion have different virological characteristics

The characteristic differences between patients with and without loss of hepatitis B virus (HBV) DNA after achieving hepatitis B e antigen seroconversion were analyzed by comparing changes in HBV DNA and HBV core-related antigen levels during a period from 3 years before to 3 years after the seroconversion. Of the 24 seroconverters, 6 (inactive replication group) showed continuous loss of HBV DNA in serum after the seroconversion and the remaining 18 did not lose HBV DNA (active replication group). The HBV DNA level was similar between the two groups, while the HBV core-related antigen level was significantly lower in the active replication group than in the inactive replication group before the seroconversion. The levels of both HBV DNA and HBV core-related antigen decreased remarkably around the time of seroconversion in the inactive replication group, while these levels did not change or decreased slightly in the active replication group. After the seroconversion, the HBV DNA level was significantly higher in the active replication group than in the inactive replication group, while the HBV core-related antigen level was similarly low between the two groups. Because the serum level of HBV core-related antigen mainly reflects that of HBe antigen, the low level of HBV core-related antigen seen after seroconversion in both groups might have contributed to the occurrence of seroconversion. The precore and core promoter mutations which cause diminished excretion of hepatitis B e antigen were significantly more frequent in the active replication group than in the inactive replication group. It was therefore considered that the seroconversion was caused mainly by a decrease in viral replication in the inactive replication group, and mainly by a decrease in HBe antigen production in the active replication group.

Hepatitis B Virus e Antigen Variants

More than 300 million people worldwide are chronically infected with hepatitis B virus (HBV). Considering the very short generation time for a virus, and the high error rate associated with the reverse transcription step of HBV replication, decades of HBV infection are probably equivalent to million years of human evolution. The most important selective force during the natural course of HBV infection appears to be the immune response. The development of anti-HBe antibody in hepatitis B patients usually correlates with reduction of HBV viremia. As a consequence, escape mutants of anti-HBe are selected. The core promoter mutants express less HBe antigen (HBeAg) through transcriptional down regulation, while precore mutants express truncated products. We recently identified additional mutations that modulate HBeAg translation initiation, proteolytic cleavage, and secondary structure maintenance through a disulfide bond. The core promoter mutants have been associated with the development of fulminant hepatitis during acute infection and liver cancer during chronic infection. Consistent with their enhanced pathogenicity, core promoter mutants were found to replicate at up to 10-fold higher levels in transfected human hepatoma cells than the wild-type virus. Moreover, some core promoter mutants are impaired in virion secretion due to missense mutations in the envelope gene. These virological properties may help explain enhanced pathogenicity of core promoter mutants in vivo.

Long-term results of lamivudine monotherapy in Korean patients with HBeAg-positive chronic hepatitis B: response and relapse rates, and factors related to durability of HBeAg seroconversion

OBJECTIVE

The aim of this study was to evaluate retrospectively the long-term effects of lamivudine in 461 Korean patients with chronic hepatitis B who were treated for more than 12 months.

METHODS

The annual rates of virological response and breakthrough were examined and the predictive factors for post-treatment relapse in 114 patients who achieved hepatitis B e antigen (HBeAg) loss or seroconversion after lamivudine therapy were also analyzed.

RESULTS

During follow-up, the rates of HBeAg seroconversion after 1, 2, 3, 4 and 5 years of treatment were 22.9, 33.2, 47.6, 54.2 and 58.8%, respectively, while those for virological breakthrough at 1, 2, 3 and 4 years were 8.2, 41.7, 55.7 and 64.8%, respectively. Ninety-five patients (20.6%) had HBeAg seroconversion and 19 (4.1%) showed HBeAg loss alone with disappearance of hepatitis B virus DNA in serum. Seroconversion was higher with prolonged treatment in patients who had elevated serum alanine aminotransferase. The cumulative relapse rates in the seroconversion group were 52.0 and 55.7% 1 and 2 years after treatment, respectively. Age and the duration of additional treatment were significant predictive factors for post-treatment relapse. Patients aged 12 months after seroconversion had the lowest relapse rate (p < 0.001).

CONCLUSIONS

These results suggest that additional treatment for over 12 months after HBeAg seroconversion in younger patients may produce a better long-term outcome.

Nucleotide mutations associated with hepatitis B e antigen negativity

One hundred and forty four patients with chronic hepatitis B were tested to identify new mutations associated with hepatitis B e antigen (HBeAg) negativity, using a full genome sequence analysis. All the patients were Chinese and had hepatitis B virus infection of genotype C. Patients with none of the pre-core or core promoter mutations were significantly (P < 0.001) less common in the group with anti-HBe (13%) than in the group with HBeAg (56%). The complete nucleotide sequence was determined in four anti-HBe-positive patients who had neither pre-core nor core promoter mutations and in five HBeAg-positive patients who also had neither of these mutations (the groups were matched for age and sex). Six mutations were found to be significantly more common in the former group than in the latter: G529A (3/4 vs. 0/5), C934A (4/4 vs. 1/5), A1053G (4/4 vs. 1/5), G1915T/A (4/4 vs. 0/5), T2005C/A (4/4 vs. 0/5), and C3026T (3/4 vs. 0/5). Three of the six mutations were significantly more common in the four anti-HBe-positive patients who had neither pre-core nor core promoter mutations, compared to 11 HBeAg-positive patients who had pre-core and core promoter mutations, and also compared to 15 anti-HBe-positive patients who had pre-core and core promoter mutations, suggesting further the specificity of these mutations. Of the six mutations, two resulted in amino acid substitution in the polymerase protein, and one is located near the enhancer I region. The results suggest that the six newly discovered mutations are associated with HBeAg negativity.

Genotype prevalence, viral load and outcome of hepatitis B virus precore mutant infection in stable patients and in patients after liver transplantation

OBJECTIVE

The precore mutant is detectable in most Israeli patients with persistent hepatitis B virus (HBV) infection. The aim of this study was to determine the prevalence of HBV genotypes, viral load and outcome of precore mutant infection in stable patients and in patients after liver transplantation.

METHODS

The prevalence of HBV genotype and viral load were investigated in 81 patients with HBV precore mutant infection. Of these, 50 patients (40 males, 10 females; mean age 43.4 +/- 11.0 yr) underwent liver transplantation and were serum HBV DNA-negative by hybridization at the time of transplantation. Patients received long-term HBV immunoprophylaxis and immunosuppression, and lamivudine in cases of graft HBV recurrence. The remaining 31 patients were stable, with serum anti-HBe-positivity. Genotypes were tested by restriction fragment length polymorphism of an S gene amplicon. Precore mutations were studied with an INNO-LiPA probe assay.

RESULTS

Follow-up was 46.6 +/- 37.7 months. Most of the transplanted group was of Middle Eastern origin (53.6%); the remainder were from Eastern Europe (21.4%), Western Europe and the USA (10.8%), Africa (7.1%), and Asia (7.1%). In the transplanted group, the pre-transplant HBV genotype D was the most prevalent (96%), while genotype A was found in only 4%. Eleven patients (22%) developed recurrent HBV infection post-transplantation. There were no differences in genotype distribution between patients with graft reinfection or lamivudine resistance and patients without recurrence. Mean viral load at recurrence was 148.4 x 10(6) +/- 60.4 x 10(6) copies/mL. The stable group had a similar origin and HBV genotype prevalence, but a lower mean viral load of 12.4 x 10(6) +/- 29.4 x 10(6) copies/mL (p = 0.007). The prevalence of mutations at the precore region and codon 28 was similar in both groups.

CONCLUSIONS

The chronic precore mutant HBV-infected patients were characterized as follows: (i) genotype D was the most frequent genotype, (ii) the HBV genotype distribution was similar in patients with stable infection and after liver transplantation, (iii) viral load at recurrence was significantly higher than in stable infection, and (iv) HBV genotype was unrelated to the development of recurrence or lamivudine resistance in the tested population.

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.

Significance of HBV DNA levels in liver histology of HBeAg and Anti-HBe positive patients with chronic hepatitis B

OBJECTIVE

To determine the relationship between hepatitis B virus (HBV) DNA levels and total histologic activity index (HAI), necroinflammation (HAI-NI), and fibrosis (HAI-F) scores.

PATIENTS AND METHODS

Liver histology and HBV DNA levels were determined in 94 patients with chronic hepatitis B.

RESULTS

There was no association between HBV DNA levels and liver histology in hepatitis-B-e antigen-positive patients (n = 43). In anti-HBe-positive patients (n = 51), HBV DNA levels correlated positively with HAI-NI (r = 0.31, p= 0.014) and HAI-F (r = 0.33, p= 0.017) scores. Though the majority of anti-HBe-positive patients with HBV DNA levels <10(5) copies/ml had mild necroinflammation and no fibrosis, 14.3% had established fibrosis. Anti-HBe-positive patients with core promoter mutations had a poorer histology compared to those without. There was no difference in the histology between anti-HBe-positive patients with and without precore mutations. Alanine aminotransferase (ALT) level correlated positively with HAI-NI score. Patients with persistently normal ALT levels had a significantly lower median HAI-NI score compared to patients with either persistently or intermittently elevated ALT levels.

CONCLUSIONS

In anti-HBe-positive patients, though HBV DNA level <10(5) copies/ml was associated with better histology, 14.3% patients had established fibrosis. Further studies to define a better cut-off HBV DNA level to differentiate low- and high-risk patients for disease progression are required.

Basal core promoter and precore mutations in the hepatitis B virus genome enhance replication efficacy of Lamivudine-resistant mutants

During chronic hepatitis B virus (HBV) infection, mutations in the precore (PC) or basal core promoter (BCP) region affecting HBV e antigen (HBeAg) expression occur commonly and represent the predominant virus species in patients with HBeAg-negative chronic hepatitis B. The PC mutation (G1896A+C1858T) creates a translational stop codon resulting in absent HBeAg expression, whereas BCP mutations (A1762T/G1764A) reduce HBeAg expression by transcriptional mechanisms. Treatment of chronic HBV infection with lamivudine (LMV) often selects drug-resistant strains with single (rtM204I) or double (rtL180M+rtM204V) point mutations in the YMDD motif of HBV reverse transcriptase. We cloned replication-competent HBV vectors (genotype A, adw2) combining mutations in the core (wild type [wt], PC, and BCP) and polymerase gene (wt, rtM204I, and rtL180M/M204V) and analyzed virus replication and drug sensitivity in vitro. Resistance to LMV (rtM204I/rtL180M+rtM204V) was accompanied by a reduced replication efficacy as evidenced by reduced pregenomic RNA, encapsidated progeny DNA, polymerase activity, and virion release. PC mutations alone did not alter virus replication but restored replication efficacy of the LMV-resistant mutants without affecting drug resistance. BCP mutants had higher replication capacities than did the wt, also in combination with LMV resistance mutations. All nine HBV constructs showed similar sensitivities to adefovir. In conclusion, BCP-PC mutations directly impact the replication capacity of LMV-resistant mutants. PC mutations compensated for replication inefficiency of LMV-resistant mutants, whereas BCP mutations increased viral replication levels to above the wt baseline values, even in LMV-resistant mutants, without affecting drug sensitivity in vitro. Adefovir may be an effective treatment when combinations of core and polymerase mutations occur.

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

Precore nucleotide 1896 and core promoter mutations may account for hepatitis B e antigen (HBeAg) seroconversion in chronic hepatitis B virus (HBV) infection, yet the mutational profiles of the core promoter are largely unknown in children. An age-matched, case-control study enrolled 110 chronic HBV-infected children, including 55 HBeAg seroconverters and 55 nonseroconverters. Precore and core promoter genes of HBV were sequenced and the serum viral genomes were genotyped from three serial serum samples of the seroconverters and from one serum sample of the nonseroconverters. Higher frequency of A1775G and G1799C mutation rates and lower frequency of A1752G mutation rate were found in the seroconverters. Precore 1896 mutation appeared more in seroconverters than in nonseroconverters (45.5% versus 10.9%; p < 0.001). 1762 + 1764 mutation rates were not different between the seroconverters (9.1%) and the nonseroconverters (5.5%). Genotype B was the major type. Genotype C was associated with core promoter 1762 + 1764 mutations in the seroconverter group (p = 0.023). The conclusions of this study include the following: 1) mutations of core promoter at nucleotide position 1752, 1775, and 1799 have significant correlations with HBeAg seroconversion; 2) core promoter 1762 + 1764 mutations play a minimal role in HBeAg seroconversion; 3) precore 1896 mutant accounted for half of childhood HBeAg seroconversion; 4) genotype C is associated with 1762 + 1764 mutations during the process of HBeAg seroconversion.

A case-control study for differences among hepatitis B virus infections of genotypes A (subtypes Aa and Ae) and D

There are two subtypes of hepatitis B virus genotype A (HBV/A) and they are provisionally designated Aa ("a" standing for Africa/Asia) and Ae ("e" for Europe). In a case-control study, 78 HBV/Aa, 78HBV/Ae, and 78HBV/D carriers from several countries were compared. The prevalence of HBe antigen (HBeAg) in serum was significantly lower in carriers of HBV/Aa than in carriers of HBV/Ae (31% vs. 49%; P = .033), with a difference more obvious in the carriers aged 30 years or younger (34% vs. 67%; P = .029). HBV DNA levels in the carriers of HBV/Aa (median, 3.46 log copies/mL; 95% CI, 2.93-3.95) were significantly lower than those of carriers of HBV/Ae (6.09 log copies/mL; 95% CI, 4.24-7.64) or of carriers of HBV/D (5.48 log copies/mL; 95% CI, 4.06-7.02), regardless of the HBeAg status (P < .001). The most specific and frequent substitutions in 54 HBV/Aa isolates were double substitutions for T1809 (100%) and T1812 (96%) immediately upstream of the precore initiation codon, which would interfere with the translation of HBeAg in HBV/Aa infections. They were not detected in 57 HBV/Ae or 61 HBV/D isolates examined. The double mutation in the core promoter (T1762/A1764) was more frequent in both HBV/Aa (50%) and HBV/Ae (44%) than in HBV/D isolates (25%; P < .01), whereas the precore mutation (A1896) occurred in HBV/D isolates only (48%; P < .0001). In conclusion, the clearance of HBeAg from serum may occur by different mechanisms in HBV/Aa, HBV/Ae, and HBV/D infections, which may influence clinical manifestations in the Western countries where both genotypes A and D are prevalent.

Regulation of hepatitis B virus core promoter by transcription factors HNF1 and HNF4 and the viral X protein

Hepatitis B virus (HBV) core promoter contains a binding site for nuclear receptors. A natural double mutation in this binding site, which changes nucleotide (nt) 1765 from A to T and nt 1767 from G to A, selectively abolishes the binding of several nuclear receptors without affecting that of HNF4. This double mutation also creates a binding site for the transcription factor HNF1 and changes two amino acids in the overlapping X protein sequence. In this study, we have examined the roles of HNF1, HNF4, and the X protein in the regulation of the core promoter activities in Huh7 hepatoma cells. Our results indicate that HNF4 could stimulate the expression of the precore RNA and the core RNA from the core promoter of both the wild-type (WT) HBV and the double mutant, although its effect on the former was more prominent. In contrast, HNF1, which did not affect the WT core promoter, suppressed the precore RNA expression of the double mutant. Further analysis using HBV genomic constructs, with and without the ability to express the X protein, indicates that the X protein did not affect the HNF4 activity on the core promoter and affected the HNF1 activity on the core promoter of only the double mutant. Thus, our results indicate that the phenotypic differences of HBV WT and double-mutant core promoters are at least partially due to the differential activities of HNF1, HNF4, and the X protein on these two promoters.

Complete hepatitis B virus genome analysis in HBsAg positive mothers and their infants with fulminant hepatitis B

Background

After perinatal transmission of hepatitis B virus, infants of anti-HBe positive HBsAg carrier mothers may develop fulminant hepatitis B. Previously it has been suggested, that fulminant hepatitis B in adults was associated with specific mutations in the HBV-genome. The aim of this study was to investigate, whether specific viral variants are associated with fulminant hepatitis B in young infants.

Methods

The complete HBV-genomes of five mothers and their infants with fulminant hepatitis were isolated from the sera, amplified and directly sequenced.

Results

Between 6 and 43 base pair exchanges between the HBV genomes of the infants and their mothers were identified. The mutations spread over the entire virus genome. Nucleotide exchanges in the basic core promotor and precore region were identified in all cases. A heterogeneous virus population was detected in four mothers.

Conclusions

Many new mutations were proved to emerge during fulminant hepatitis B in infants, who had been perinatally infected. HBeAg negative variants were the predominant population in all children, whereas these mutants could only be detected as subpopulations in four mothers. The data suggest that the selection of a specific HBeAg negative viral strain may be associated with the development of fulminant hepatitis B in children.

Fibrosing cholestatic hepatitis secondary to precore/core promoter hepatitis B variant with lamivudine resistance: successful retransplantation with combination adefovir dipivoxil and hepatitis B immunoglobulin

Fibrosing cholestatic hepatitis (FCH) is a peculiar variant of hepatitis B virus (HBV) infection in immunocompromised patients characterized by rapid viral replication. Posttransplant patients receiving lamivudine for prophylaxis or treatment of HBV infection may develop drug resistance due to viral mutants, but FCH is rare because escape mutants are usually replication deficient. We report the development of FCH due to lamivudine-resistant HBV mutants in 2 patients at 12 and 13 months after liver transplantation. Rapidly progressive graft failure, accompanied by an escalating HBV DNA level, developed within weeks of onset. Analysis of gene sequence variation by polymerase chain reaction (PCR) and direct sequencing showed that both had a core promoter variant A1762T/G1764A and 1 had a concomitant precore stop codon G1896A variant in prelamivudine and postrecurrence serum samples. Comparison of the HBV polymerase gene in the 2 serum samples revealed a single mutation with methionine-to-isoleucine substitution at codon 552 (M552I) in both patients. "Add-in" treatment with adefovir dipivoxil resulted in a more than 2 to 3log10 reduction in HBV DNA level within 2 weeks and retransplantation was performed with adefovir dipivoxil and hepatitis B immunoglobulin (HBIG) prophylaxis. Both patients were alive at 15 months and 48 months after retransplantation, with normal graft function and serum negative for HBsAg and HBV DNA by quantitative PCR (< 200 copies/mL). The current report demonstrates that recurrent graft infection by precore/core promoter variant with lamivudine-resistant escape mutation may result in FCH. With combination of adefovir and high-dose HBIG, however, long-term survival can be achieved after retransplantation.

Mutations in the basic core promoter region of hepatitis B virus. Relationship with precore variants and HBV genotypes in a Spanish population of HBV carriers

BACKGROUND/AIMS

To determine the prevalence and significance of hepatitis B virus (HBV) basic core promoter (BCP) mutations and to establish their relationship with precore (preC) mutations, HBV genotypes and HBV-DNA levels.

METHODS

BCP and preC mutations and genotypes were determined by sequencing.

RESULTS

Genomic analysis was performed in 129 (71%) of 182 patients. BCP mutations were detected in 83% of 18 HBeAg-negative (e-) chronic hepatitis B (CHB) patients with fluctuating ALT levels, and in 76% of 58 e- CHB with elevated ALT. The prevalence was lower and similar, 55% in 30 HBeAg-positive CHB (e+ CHB) with elevated ALT and in 23 e- inactive carriers. Frequency of preC mutations was higher in e- CHB (80%) than in e- inactive carriers (65%). Among e- CHB, patients with elevated ALT and preC mutations at nt 1896 showed highest HBV-DNA, regardless of BCP mutations. BCP mutations were similar in genotypes A and D, while preC mutations were most common in genotype D (82 vs. 40%). Simultaneous presence of the main BCP (1762, 1764) and preC (1896, 1899) mutations was associated with the degree of histological injury.

CONCLUSIONS

Combined BCP and preC mutational and genotype analysis provides clinically relevant information in the study of HBV infection.

Evaluation of a line probe assay for identification of hepatitis B virus precore variants in serum from chronic hepatitis B carriers

A prototype line probe assay (LiPA) for identifying hepatitis B virus (HBV) precore variants (INNO-LiPA HBV precore) was evaluated using a panel of 50 sera from 46 patients with HBV infection. The assay detected sequence variations detected commonly in the precore promoter region and in amino acid codons 28 and 29 of the precore gene. There was strong agreement between INNO-LiPA HBV precore results and those of a codon 28 point mutation assay (PMA), with identical results obtained in 40 of 43 sera (93%) typeable by both assays (kappa coefficient (kappa)=0.90). In addition, the precore codon 29 sequence identified by the INNO-LiPA HBV precore was confirmed by nucleotide sequencing in all seven samples analysed. However, the INNO-LiPA HBV precore identified precore promoter sequences much less efficiently. The prototype assay could identify codon 28/29 sequences from as little as 10 HBV genome equivalents in 10 microl serum, and in experiments using artificially prepared mixtures of variants could identify a minor component constituting 2.5% of the total viral DNA population. The INNO-LiPA HBV precore was also straightforward technically and rapid, and is therefore likely to be useful for epidemiological investigations into the prevalence, distribution and clinical significance of HBV precore variants.

Effect of acute self-limited hepatitis C virus (HCV) superinfection on hepatitis B virus (HBV)-related cirrhosis. Virological features of HBV-HCV dual infection

We investigated the virological impact of acute hepatitis C virus (HCV) superinfection on two patients with hepatitis B virus (HBV)-related cirrhosis. In both patients, chronic HBV-infection persisted while acute HCV infection resolved spontaneously. HBV DNA was transiently suppressed in both patients but increased with HCV resolution. In Case 1 (HBeAg-positive; wild type of basic core promoter [BCP] and precore [PreC]), fluctuations of HBV DNA and HBeAg state were accompanied by mutations of the BCP and PreC. In Case 2 (HBeAg-negative; mutant type of the BCP and PreC), changes in HBV DNA levels were associated with mutations of PreC. In both cases, mutant PreC changed to the wild type upon HCV resolution, and no nucleotide A insertion at position 193 of the HCV 5'-untranslated region, which influences HCV spontaneous clearance, was detected. The putative DNA-binding motif in the HCV core was SPRG (amino acids 99-102). HCV infection was associated with changes in the nucleotide sequences of the binding site for the nuclear receptor family in HBV enhancer 2 (Enh2) including the BCP rather than Enh1. Our results suggest that the impact of acute HCV infection on chronic HBV infection varies according to HBV virological state.

In vitro and in vivo interactions between the hepatitis B virus protein P22 and the cellular protein gC1qR

gC1qR, a mitochondrial matrix protein, was identified as the main cellular partner of the hepatitis B virus P22 protein. We demonstrated by immunofluorescence studies that some P22 molecules were colocalized with the endogenous gC1qR in both the cytoplasm and the nucleus but never in the mitochondria. We also showed that the last 34 amino acids of P22 were involved in the association with gC1qR.

Evolution of precore/core promoter mutations in hepatitis B carriers with hepatitis B e antigen seroreversion

The evolution of precore stop codon mutation (A1896) and dinucleotide mutation (T1762/A1764) in the basic core promoter (BCP) of hepatitis B virus (HBV) genome during transient seroconversion and seroreversion of hepatitis B e antigen (HBeAg) remains unclarified. Five HBeAg-positive HBV carriers who experienced transient seroconversion followed by seroreversion of HBeAg (Group I, 3.3%) and 3 HBeAg-negative HBV carriers with documented reversion of HBeAg (Group II, 2.5%) in a prospective cohort of 272 patients with chronic hepatitis B were thus identified. The sequential changes at the precore nucleotide 1896 and BCP dinucleotide 1762/1764 were determined by polymerase chain reaction and direct sequencing. At enrollement, precore A1896 and BCP T1762/A1764 were noted in 4 (50%) and 1 (13%) of the eight patients. During a median follow-up period of 58 months (range: 31-76 months), 12 episodes of transient HBeAg seroconversion followed by seroreversion were encountered in Group I patients and 3 episodes of HBeAg seroreversion in Group II patients. Accompanying acute exacerbations were found in two-thirds of patients with either HBeAg seroconversion or seroreversion. Overall, precore nucleotide A1896 remained identical in 73% and 83% of the seroconversion and seroreversion events, respectively. BCP dinucleotide T1762/A1764 remained unchanged in 94% and 92% of the seroconversion and seroreversion events, respectively. At the end of follow-up, only one had both precore and BCP mutations. In conclusion, these data suggested that HBeAg seroreversion might be due to the lack of sustained precore and BCP mutations after HBeAg seroconversion. Although uncommon, HBeAg seroreversion can be associated with hepatitis exacerbation.

Core promoter/pre-core mutations are associated with lamivudine-induced HBeAg loss in chronic hepatitis B with genotype C

BACKGROUND/AIMS

To clarify the factors associated with the efficacy of lamivudine.

METHODS

Variables including basic core promoter (BCP) and pre-core (PreC) mutations were evaluated in 60 chronic hepatitis B e antigen (HBeAg)-positive patients with genotype C. Thirty patients were treated with lamivudine and the remaining 30 patients were age- and sex-matched controls.

RESULTS

Severe fibrosis was significantly more frequent in patients with the BCP-mutant/PreC-wild (MW) and BCP-mutant/PreC-mutant (MM) patterns compared to BCP-wild/PreC-wild (WW) pattern (P=0.02). The cumulative rates of HBeAg loss at 6, 12 and 18 months were significantly higher in the lamivudine group (14.2, 36.3, and 60.9%) compared with the control group (17.6, 17.6, and 24.5%, P=0.03), and was especially pronounced in patients with the MW pattern (P=0.04). The rate of lamivudine-related HBeAg loss was significantly lower in patients with the WW pattern (P=0.03). Factors correlating with HBeAg loss were histological fibrosis and activity, hepatitis B virus-DNA levels, BCP/PreC mutation and lamivudine therapy. Multivariate analysis revealed BCP/PreC mutations and fibrosis were independent factors for HBeAg loss.

CONCLUSIONS

With specific reference to the genotype C, we found earlier HBeAg loss was expected in patients carrying MM and MW patterns, while the efficacy of lamivudine was limited in patients with the WW pattern.

Sequence variation upstream of precore translation initiation codon reduces hepatitis B virus e antigen production

BACKGROUND & AIMS

Most South African hepatitis B virus strains harbor point mutations immediately upstream of the precore AUG codon. The aim of this study was to determine their effect on hepatitis B e antigen expression.

METHODS

The hepatitis B virus DNA sequence around the precore region was determined from sera of 45 black South Africans. The South African mutations were introduced into hepatitis B virus dimers of the same genotype, and hepatitis B e antigen was quantified from culture medium of transfected HepG2 or Huh7 cells.

RESULTS

The South African sequence changes were easily detectable in the acute, hepatitis B e antigen-positive phase of infection, suggesting that they were stable traits and were not selected by immune pressure. Triple mutations at the -5, -3, and -2 positions of the AUG codon severely impaired hepatitis B e antigen expression (P < 0.001). The frequent double mutation at the -5 and -2 positions moderately reduced hepatitis B e antigen levels (P < 0.001) to an extent comparable to that of the common core promoter mutations (1762(T)1764(A)). The presence of both South African and core promoter mutations diminished hepatitis B e antigen expression in an additive manner. It is interesting to note that the triple South African mutations enabled core protein translation from precore messenger RNA, which could rescue the replication defect of a hepatitis B virus genome with an ablated core gene.

CONCLUSIONS

We have identified a novel class of hepatitis B e antigen variants with reduced hepatitis B e antigen translation by a ribosomal leaky scanning mechanism. Reduction in hepatitis B e antigen expression may contribute to accelerated seroconversion from hepatitis B e antigen to its antibody in black South Africans infected with hepatitis B virus very early in life.

Integration of hepatitis B virus containing mutations in the core promoter/X gene in patients with hepatocellular carcinoma

Integration of hepatitis B virus is thought to be an essential step in hepatitis B virus associated hepatocarcinogenesis. Mutations at nucleotides 1762 and 1764 in the hepatitis B virus, within a sequence encoding both the core promoter gene and the X gene, have been found frequently in patients with hepatocellular carcinoma. However, integration of these mutant sequences has not been reported to date.

METHODS

A 228-base pair segment of the hepatitis B virus core promoter gene was amplified from hepatocellular carcinomas and adjacent non-tumourous liver tissue by nested PCR and sequenced. Integration of hepatitis B virus into human genomic DNA was investigated using the 'genome walking' method.

RESULTS

Point mutations were found in both hepatitis B virus nucleotides 1762 and 1764 in 8 of 14 hepatocellular carcinoma tissues (57%) and in 11 of 14 adjacent non-tumourous liver tissues (79%). Three patients were evaluated using the 'genome walking' method; all were found to have hepatitis B virus DNA integrated in their hepatocellular carcinoma (two patients) and/or in their non-tumourous liver tissue (three patients). Integration occurred in all tissues near host genomic sites that are prone to integration. Hepatitis B virus was integrated at or near the hepatitis B virus DR1 site in all samples, and all contained truncated X gene sequences that have been reported to be capable of producing fusion transcripts with transactivation potential.

CONCLUSIONS

Integrated hepatitis B virus DNA containing core promoter mutations at nucleotides 1762 and 1764 was found in hepatocellular carcinoma and/or adjacent non-tumourous liver tissue of three patients. These findings leave open the possibility that insertional mutagenesis or transactivation by fusion transcripts resulting from hepatitis B virus integration could play a role in hepatocarcinogenesis in some patients.

Exploring the biological basis of hepatitis B e antigen in hepatitis B virus infection

The function of the hepatitis B e antigen (HBeAg) is largely unknown because it is not required for viral assembly, replication, or infection. In this report we chronicle clinical and experimental studies in an attempt to understand the role of HBeAg in natural infection. These studies largely have focused on clinical-pathologic features of HBeAg-negative variants in acute and chronic HBV infection, mutational analysis in animal models of hepadnavirus infection, and the use of transgenic murine models. The clinical and experimental data suggest that serum HBeAg may serve an immunoregulatory role in natural infection. To the contrary, cytosolic HBeAg serves as a target for the inflammatory immune response. These dual roles of the HBeAg and its ability to activate or tolerize T cells show the complexity of the interactions between the HBeAg and the host during HBV infection.

Prevalence of HBV precore/core promoter variants in the United States

Variants in the precore (G(1896)A) and core promoter (A(1762)T, G(1764)A) regions of hepatitis B virus (HBV) may be related to serum HBV DNA levels and severity of liver disease. The aims of this nationwide study were to determine the prevalence of HBV precore/core promoter variants in the United States and the association between these variants and patient demographics, HBV genotypes, serum HBV DNA level, and severity of liver disease. A total of 694 consecutive chronic HBV-infected patients seen in 17 U.S. liver centers during a 1-year period were enrolled. Demographic, clinical, and laboratory data were collected. Sera were tested for HBV genotypes as well as precore and core promoter variants by line-probe assays. Quantitative HBV DNA levels were determined using Cobas Amplicor HBV Monitor kits. Precore and core promoter variants were found in 27% and 44% of patients with chronic HBV infection in the United States. Precore and core promoter variants were more common in hepatitis B e antigen (HBeAg)-negative than in HBeAg-positive patients (precore, 38% vs. 9%; core promoter, 51% vs. 36%; respectively, P <.001). The prevalence of these variants was related to ethnicity, place of birth, and HBV genotypes. Patients with core promoter variants were more likely to have hepatic decompensation. Precore and/or core promoter variants were associated with higher serum HBV DNA levels in HBeAg-negative but not in HBeAg-positive patients. In conclusion, HBV precore and core promoter variants are not rare in the United States. Physicians should be aware of the existence of HBV precore and core promoter variants and the clinical condition of "HBeAg-negative chronic hepatitis."

Hepatitis B virus: prevalence of precore/core promoter mutants in different clinical categories of Indian patients

To determine the association of precore (Pre-C)/basal core promoter (BCP) mutants with clinical outcome of hepatitis B in Western India, 192 hepatitis B virus (HBV) infected individuals were investigated. HBV-DNA PCR positivity among asymptomatic hepatitis B surface antigen (HBsAg) positive carriers (61/100) was lower (P < 0.0001) than chronic hepatitis B (CHB), acute (P = 0.0001), and fulminant hepatitis B patients (P = 0.047). Pre-C status was based on restriction fragment length polymorphism (RFLP, n = 153) and sequencing (n = 118). Prevalence of Pre-C mutants was higher among carriers (23/61) than CHB (10/62, P = 0.0071) or acute (3/22; P = 0.037) patients. Children from carrier and CHB categories showed significantly higher circulation of Pre-C-wild than mutant HBV. Clinical manifestations were independent of BCP mutations (1762/64-T/A). Hepatitis B e antigen (HBeAg) negative CHB patients [62.5% (15/24)] were circulating wild HBV. Higher HBV-DNA levels were associated with chronic hepatitis and HBeAg positivity, whilst Pre-C mutant positives had lower levels. BCP mutations did not affect HBV-DNA levels. Multivariate regression analysis identified HBeAg (OR = 4.3) and Pre-C mutants (OR = 3.1) to be associated with chronic hepatitis and carriers respectively. In a separate sub-set analysis (n = 59), HBV-DNA level was identified as the only variable. In conclusion, chronic or fulminant hepatitis B was not associated with Pre-C or BCP mutants and switching over to Pre-C mutant was beneficial for the infected individual in maintaining disease free status for extended periods.

Hepatitis B virus genotypes in the United States: results of a nationwide study

BACKGROUND & AIMS

Hepatitis B virus (HBV) genotypes may be related to severity of liver disease and treatment response. The aims of this nationwide study were to determine the prevalence of HBV genotypes in the United States and the association between HBV genotypes and patient demographics, mode of infection, and clinical status.

METHODS

A total of 694 consecutive chronic HBV-infected patients seen in 17 U.S. liver centers during a 1-year period were enrolled. Demographic, clinical, and laboratory data were collected. Sera were tested for HBV genotyping, precore, and core promoter variants by line-probe assays.

RESULTS

All 7 HBV genotypes (A-G) were found, with genotypes A and C the most common. The prevalence of HBV genotypes was different in different regions of the United States. A strong correlation was found between HBV genotypes and ethnicity. HBV genotype A was prevalent among white and black patients, whereas genotypes B and C were most common among Asian patients. The predominant genotype among patients born in the United States, Europe, the Far East, and Southeast Asia were A, D, C, and B, respectively. Genotypes A and C were associated with a higher prevalence of hepatitis B e antigen. Precore variant was detected in 27% of patients and core promoter variant in 44% of patients.

CONCLUSIONS

Our study suggests that the epidemiology of HBV infection in the United States may have changed over time as a result of immigration from countries with a high prevalence of HBV infection. HBV genotypes may account for the heterogeneity in disease manifestations among patients with chronic HBV infection.

Genotypes and phylogenetic characterization of hepatitis B and delta viruses in Egypt

Hepatitis B virus (HBV) and hepatitis D virus (HDV) sequences among HBV carriers from Egypt have not been evaluated sufficiently. The genotypes of HBV isolated from 105 serum samples from Egyptian carriers were determined. Four complete genomes and 11 entire preS1/S2/S genes were sequenced and evaluated. All serum samples were classified into HBV genotype D using serologic and genetic methods. The length of four complete nucleotide sequences was 3,182 bp. In all 15 samples, the common 33 nucleotides (11 amino acids) deletions in the preS1 region specific for HBV genotype D were observed. In the phylogenetic analysis based on the complete nucleotide sequences, all samples were clustered with the HBV isolates reported from previously Western and Mediterranean countries with nucleotide homology ranging from 96.0-98.0%. Of 75 HBsAg positive samples, anti-HDV was found in 15 (20%), and HDV RNA was detected in 9 of 15 (60%). The proportion of the patients with liver disease was higher in HBV carriers of anti-HDV positive with HDV RNA than in HBV carriers of anti-HDV positive without HDV RNA (P < 0.05). In the phylogenetic analysis based on the sequences in nucleotide position 853-1267 of HDV, nine samples were classified into HDV genotype I with the nucleotide homology ranging from 88.3-92.1% (mean; 90.5%) and clustered with HDV strains reported previously from Ethiopia, Somalia, Egypt, and Lebanon. These results indicate that HBV genotype D and HDV genotype I are most prevalent in Egypt, and HDV co-infection in HBV carriers is related to severity of liver disease.

A case-control study for early prediction of hepatitis B e antigen seroconversion by hepatitis B virus DNA levels and mutations in the precore region and core promoter

Factors influencing and predictive of seroconversion from hepatitis B e antigen (HBeAg) to antibody (anti-HBe) were sought in a case-control study of 61 patients with chronic hepatitis B who had been observed from 5 years before to 1 year after seroconversion, and 32 patients who did not seroconvert during the entire 6-year period. Almost all of the patients (96%) were infected with HBV genotype C. HBV DNA levels began to decrease 3 years before seroconversion in the seroconverters, while they remained high in the non-converters. The frequency of precore mutation and the loss of HBeAg (A1896) started to increase 1 year before in the converters, and became significantly higher at seroconversion (23 vs. 3%, P = 0.030) than that in the non-converters. Double mutation in the core promoter (T1762/A1764) was more common in the seroconverters than in the non-converters 5 years before seroconversion (48 vs. 28%), and became significantly more frequent at seroconversion (65 vs. 41%, P = 0.046). Seroconversion occurred in 75% of the patients with at least HBV DNA levels <5.5 logarithmic equivalents/mL; precore mutation in 20% or more of HBV DNA; or core promoter mutation. Seroconversion occurred in 50% of those patients within 1 year, 88% within 2 years, and 93% within 5 years. These results indicate that a decrease in HBV DNA levels and mutations in the precore region and the core promoter were associated significantly and complementarily with seroconversion, and each of them or a combination thereof was predictive of seroconversion years ahead.

Hepatitis B reactivation in patients positive for hepatitis B surface antigen undergoing autologous hematopoietic cell transplantation

Hepatitis due to reactivation of hepatitis B virus is an important cause of liver-related morbidity and mortality in hepatitis B surface antigen (HBsAg) positive patients undergoing autologous hematopoeitic cell transplantation. With the recent introduction of sensitive serum HBV DNA quantitation assay, the diagnosis of hepatitis B reactivation can now be made more reliably. As these hepatitis are driven by the host immune response to a surge of hepatitis B viral load, the availability of effective nucleoside analogues which can inhibit hepatitis B viral replication has opened up new approaches to this previously untreatable condition. Up till now, two such nucleoside analogues, lamivudine and adefovir dipivoxil, have been approved for the treatment of chronic hepatitis B infection. However, further studies are needed to determine which nucleoside analogues should be chosen in this transplant setting. Due to the high dose chemotherapy generally needed in autologous hematopoeitic cell transplantation, there is a high risk of post-transplant hepatitis B reactivation. Hence, all HBsAg positive patients undergoing autologous hematopoeitic cell transplantation should preferably be treated pre-emptively with nucleoside analogous. An alternative approach is to defer treatment with nucleoside analogous until there is evidence of hepatitis B virological reactivation. However, the latter approach would need the patient's hepatitis B viral load be monitored at a very close interval and might not be cost-effective.

Rapid and sensitive assays for determination of hepatitis B virus (HBV) genotypes and detection of HBV precore and core promoter variants

Hepatitis B virus (HBV) genotypes may influence HBeAg seroconversion rates, mutational patterns in the precore (PC) and core promoter (CP) regions, severity of liver disease, and response to antiviral treatment. Development of rapid, simple, and standardized assays to detect viral genotypes and common mutations in the PC and CP regions can accelerate research on the clinical significance of these variants. We aim to assess the accuracy of a line probe assay in determining HBV genotypes and detecting HBV PC and CP variants. HBV genotypes in 701 patients and PC and CP variants in 600 patients with chronic HBV infection from China and the United States were studied using the INNO-LiPA assay. All but one (99.9%) sample were classified by the genotyping assay. All eight genotypes, i.e., A to H, were found. The INNO-LiPA genotyping assay results were completely concordant with those of sequencing. Using the INNO-LiPA PC assay, 99.8 and 94.7% samples were classifiable in the PC and CP regions, respectively. The PC assay results were completely concordant with those of sequencing in all samples that showed either wild-type or variant sequence. The line probe assay was more sensitive in detecting mixtures than was direct sequencing. By INNO-LiPA, only 50 and 27% of the samples, with mixed wild-type and variant sequence in the PC and CP region, respectively, showed mixed sequence by direct sequencing. INNO-LiPA is rapid, sensitive, and reliable-thus enabling accurate determination of HBV genotypes and detection of PC and CP variants in a large population of patients.

HBe antigen loss during lamivudine therapy is not caused by mutations in precore and core promoter genes in patients with chronic hepatitis B

HBe antigen (HBeAg) loss or seroconversion can occur during lamivudine therapy. The purpose of this study was to analyze nucleotide sequences in precore and core promoter regions, and examine the influence of mutations in these regions on the disappearance of HBeAg during lamivudine therapy. Serial serum samples were obtained from 51 patients (HBeAg loss in 26 patients) at commencement of therapy (baseline) and after 1 year of lamivudine therapy. Serum samples were amplified with PCR and nucleotide sequences of HBV were analyzed. At baseline, a precore stop codon mutation (A1896) was identified in 8 of 26 HBeAg loss patients and in 8 of 25 HBeAg non-loss patients. At 1 year, precore mutation was observed in 4 of 14 patients analyzed who showed HBeAg loss. At 1 year, however, a precore mutation was observed also in 3 of 9 analyzed patients who showed no HBeAg loss. Core promoter mutations were noted in 21 of 26 HBeAg loss patients and in 20 of 25 HBeAg non-loss patients. At 1 year, core promoter mutations were noted in 11 of 14 HBeAg loss patients and in 8 of 9 HBeAg non-loss patients. Our data suggested that during lamivudine therapy, core promoter and precore mutations do not influence HBeAg loss or seroconversion but may reduce the viral level upon HBeAg loss or seroconversion.

Genome replication, virion secretion, and e antigen expression of naturally occurring hepatitis B virus core promoter mutants

The core promoter mutants of hepatitis B virus (HBV) emerge as the dominant viral population at the late HBeAg and the anti-HBe stages of HBV infection, with the A1762T/G1764A substitutions as the hotspot mutations. The double core promoter mutations were found by many investigators to moderately enhance viral genome replication and reduce hepatitis B e antigen (HBeAg) expression. A much higher replication capacity was reported for a naturally occurring core promoter mutant implicated in the outbreak of fulminant hepatitis, which was caused by the neighboring C1766T/T1768A mutations instead. To systemically study the biological properties of naturally occurring core promoter mutants, we amplified full-length HBV genomes by PCR from sera of HBeAg(+) individuals infected with genotype A. All 12 HBV genomes derived from highly viremic sera (5 x 10(9) to 5.7 x 10(9) copies of viral genome/ml) harbored wild-type core promoter sequence, whereas 37 of 43 clones from low-viremia samples (0.2 x 10(7) to 4.6 x 10(7) copies/ml) were core promoter mutants. Of the 11 wild-type genomes and 14 core promoter mutants analyzed by transfection experiments in human hepatoma cell lines, 6 core promoter mutants but none of the wild-type genomes replicated at high levels. All had 1762/1764 mutations and an additional substitution at position 1753 (T to C), at position 1766 (C to T), or both. Moreover, these HBV clones varied greatly in their ability to secrete enveloped viral particles irrespective of the presence of core promoter mutations. High-replication clones with 1762/1764/1766 or 1753/1762/1764/1766 mutations expressed very low levels of HBeAg, whereas high-replication clones with 1753/1762/1764 triple mutations expressed high levels of HBeAg. Experiments with site-directed mutants revealed that both 1762/1764/1766 and 1753/1762/1764/1766 mutations conferred significantly higher viral replication and lower HBeAg expression than 1762/1764 mutations alone, whereas the 1753/1762/1764 triple mutant displayed only mild reduction in HBeAg expression similar to the 1762/1764 mutant. Thus, core promoter mutations other than those at positions 1762 and 1764 can have major impact on viral DNA replication and HBeAg expression.

The effects of hepatitis B virus core promoter mutations on hepatitis B core antigen distribution in hepatocytes as detected by laser-assisted microdissection

BACKGROUND/AIMS

The severity of liver damage in patients with chronic hepatitis B is dependent on several factors such as subcellular localization of hepatitis B core antigen (HBcAg) and mutation of hepatitis B virus (HBV) DNA. Here we studied the interrelationship between these two factors both in situ and in vitro.

METHODS

Hepatocytes from liver biopsies showing expression of HBcAg only in the cytoplasm (n=6), only in the nucleus (n=4) and in both cytoplasms or nucleus of different hepatocytes (n=5) were picked up by laser-assisted microdissection and were checked for nucleotide sequences of core promoter region of HBV DNA. HepG2 and Huh7 cell lines transfected with wild and mutant HBV DNA were checked for localization of HBcAg.

RESULTS

The frequencies of core promoter mutations at nucleotide (nt) 1762 and nt 1764 was significantly higher in hepatocytes with cytoplasmic expression of HBcAg compared to that of nuclear expression of HBcAg (P<0.05). Cytoplasmic expression of HBcAg was observed more frequently in HepG2 and Huh7 cells transfected with HBV mutant type (nt 1762 and 1764) than HBV wild type (P<0.05).

CONCLUSIONS

Cytoplasmic localization of HBcAg was associated with HBV DNA mutations at nt 1762 and 1764.

Distribution of hepatitis B virus (HBV) genotypes among HBV carriers in the Cote d'Ivoire: complete genome sequence and phylogenetic relatedness of HBV genotype E

The characteristics of hepatitis B virus (HBV) genotype E are not well known because only a few studies have been carried out by complete genome analysis. The aim of this study was to elucidate the distribution of HBV genotypes in Cote d'Ivoire, and to clarify the genotype-related characteristics of genotype E. The distribution of HBV genotypes among 48 HBV carriers in Cote d'Ivoire was determined using serological and genetic methods. The characteristics of genotype E were evaluated by complete genome sequences, and further investigations of small S gene, basic core promoter (BCP) mutation, and precore mutation were undertaken. HBV genotype distribution among the 48 carriers was 6.3% for genotype A, 6.3% for genotype D, and 87.4% for genotype E. Complete genomes of two genotype E strains were sequenced, and found to have 98.2% to 99.2% homology at the nucleotide level when compared with genotype E strains reported previously. In 24 genotype E carriers, the precore mutation was detected in 75% of the patients without HBeAg, in contrast to only 25% of the patients with HBeAg (P < 0.05). All 24 strains have T at nucleotide 1858 in the precore region. In contrast, BCP double mutation was detected in 17% of the patients with HBeAg, and 33% of the patients without HBeAg. These results indicated as the following: (1) genotypes A, D, and E of HBV exist in Cote d'Ivoire and genotype E is the most prevalent; (2) genotype E spread with low genetic diversity over the complete genome in West Africa; (3) HBV precore and/or BCP double variants were common among the patients with genotype E infections.

Epidemiologic and virologic characteristics of hepatitis B virus genotype B having the recombination with genotype C

BACKGROUND & AIMS

Hepatitis B virus (HBV) isolates of genotype B (HBV/B) with or without the recombination with genotype C over the precore region plus core gene have been reported.

METHODS

All the 41 HBV/B isolates having the recombination with genotype C (HBV/Ba) possessed the nucleotide 1838 of A in contrast to that of G in all 29 of those without the recombination (HBV/Bj). Taking advantage of this single nucleotide polymorphism, a restriction fragment length polymorphism method was developed that distinguished HBV/Ba from HBV/Bj.

RESULTS

HBV/Bj was detected in 90 of the 97 (93%) carriers of HBV/B from Japan, whereas HBV/Ba occurred in all 177 carriers of HBV/B from other countries (China, 20; Hong Kong, 45; Taiwan, 32; Thailand, 30; Vietnam, 30; and the United States, 20 [all of an Asian ethnicity]). In a case-control study, hepatitis B e antigen (HBeAg) and the double mutation in the core promoter (T1762/A1764) were significantly more frequent in 80 carriers each of HBV/Ba than HBV/Bj (35% vs. 18%, P < 0.05 and 33% vs. 15%, P < 0.05, respectively). Differences in the prevalence of HBeAg were more conspicuous between the carriers of HBV/Bj and HBV/Ba older than 30 years (5 of 66 or 8% vs. 16 of 62 or 26%, P < 0.01).

CONCLUSIONS

HBV/B having the recombination with genotype C is frequent in Asia, except in Japan, and HBeAg is more prevalent in carriers of HBV/Ba than HBV/Bj.

Suppression of hepatitis B virus core promoter by the nuclear orphan receptor TR4

The TR4 orphan receptor is a member of the nuclear receptor superfamily that modulates gene expression via binding to the AGGTCA direct repeat hormone response element. Here we report a functional study of TR4 interaction with the core promoter of the hepatitis B virus (HBV). The electrophoretic mobility shift assay shows that TR4 can bind to the direct repeat 1 sequence element (AGGTTAAAGGTCT, nucleotide coordinates 1757-1769, TR4RE-HBV) on the HBV core promoter. TR4 also can enhance the activity of a synthetic luciferase reporter linked with four copies of TR4RE-HBV in either liver HepG2 or non-liver H1299 cells in a dose-dependent manner. Surprisingly, TR4 represses the activity of a luciferase reporter containing the entire HBV genome sequences. Moreover, mutation of this TR4RE-HBV site in the HBV core promoter diminishes the TR4 suppression effect. This TR4-induced suppression of HBV core promoter activity is further confirmed by primer extension analysis of the HBV core RNAs, showing that TR4 represses both pre-core and core mRNAs. Further dissection of this repressive mechanism indicates that TR4 may suppress the HBV core promoter activity via repressing HNF4alpha-mediated transactivation by protein-protein interactions without inhibition of HNF4alpha DNA binding. Furthermore, our results indicate that the N- and C-terminal regions of TR4 protein are required for TR4-HNF4alpha interaction. It is possible that TR4-HNF4alpha interaction may block the HNF4alpha function that results in the suppression of HBV gene expression. Together, these results demonstrate that TR4 can serve as a negative modulator in the transcriptional regulation of HBV core gene expression.

Molecular epidemiology of gibbon hepatitis B virus transmission

Although transmission of human hepatitis B virus (HBV) variants to nonhuman primates is well documented, it remains to be elucidated whether nonhuman primate HBV is transmissible to humans. The prevalence and transmission routes of gibbon HBV were analysed in 101 captive gibbons in Thailand. Approximately 40 % of these animals showed at least one marker of HBV infection; 19 animals were chronic HBV carriers, characterized by elevated levels of alanine amino transferase and the presence of HBV DNA. Some of the chronic animals were found to be anti-HBc (HBV core antigen) negative (4 of 19), while precore promoter point mutations (nt 1762 or 1764) were determined in four animals by RFLP analysis. Phylogenetic tree analysis of the complete surface gene sequences revealed that gibbon viruses clustered separately from hepadnaviruses of other hosts. Evidence for horizontal and vertical transmission in captive gibbons was obtained. HBV DNA was also detected in the saliva of HBV carrier gibbons. Although some of the animal caretakers at the Krabok Koo Wildlife Breeding Centre were found to be chronic HBV carriers, genotype and sequence analysis did not reveal any evidence for zoonotic disease transmission.

Complete genome sequence of hepatitis B virus (HBV) from a patient with fulminant hepatitis without precore and core promoter mutations: comparison with HBV from a patient with acute hepatitis infected from the same infectious source

BACKGROUND/AIMS

There is a paucity of information regarding hepatitis B virus (HBV) from patients with fulminant hepatitis (FH) without precore (pre-C, nt 1896) and core promoter (CP, nt 1762, 1764) mutations.

METHODS

Pre-C and CP mutations were studied in eight patients with FH and 26 patients with acute hepatitis (AH) due to HBV. One patient with FH (FH1) was infected with HBV without these mutations. Interestingly, the sera of the infectious source (IS1) and of a patient with AH (AH1) infected from IS1 were available. Complete HBV genomes from these three patients were analyzed.

RESULTS

These mutations were found in seven of eight FH and five of 26 AH (P<0.01). HBV from FH1, IS1 and AH1 belonged to genotype D. Nucleotide difference between FH1 and AH1 was six of 3182 bases (nt 493, 998, 1173, 2928, 3067, and 3078). Two and five substitutions of deduced amino acid sequences were found in the pre-S1 and polymerase regions, respectively. The same nucleotide substitutions at nt 493, 1173, 2928 and 3067 were found in several patients with FH in our laboratory or GenBank.

CONCLUSIONS

These six nucleotide substitutions of HBV DNA could be candidates of mutations relating to FH.

Mutations of polymerase, precore and core promoter gene in hepatitis B virus during 5-year lamivudine therapy

BACKGROUND/AIMS

The effects of long-term lamivudine therapy on changes in polymerase and precore/core promoter mutations are unknown. The aim of this study was to determine the changes in these regions in patients with chronic hepatitis B virus (HBV) infection treated with lamivudine for 5 years.

METHODS

Serum samples obtained from 16 patients at the beginning of and during therapy were polymerase chain reaction-amplified, and nucleotide sequences of HBV analyzed.

RESULTS

By the end of 5-year therapy, mutations in YMDD motif emerged in ten patients. Mutations in L526M, M550V and M550I in polymerase were found in seven, six and six patients, respectively. The L526M mutant was found at the time or after detection of M550V/I mutant in six of seven patients. At baseline, precore and core promoter mutations were found in eight and 12 of 16 patients, respectively. Mutants of precore and core promoter were replaced by wild-type virus in each of three patients infected with mutants at 1 year. However, at 5 years of treatment, precore and core promoter mutations reappeared in some patients.

CONCLUSIONS

Our data showed that lamivudine initially selected from precore/core promoter mutants to wild-type virus, but precore mutation reappeared during prolonged therapy.

Core promoter mutations 3 years after anti-hepatitis B e seroconversion in patients with chronic hepatitis B or hepatitis B and C infection and cancer remission

OBJECTIVES

In this study, we aimed to evaluate the persistence of hepatitis B virus (HBV) DNA and the role of HBV core promoter and precore region mutations in 28 young cancer survivor patients with HBV or HBV and hepatitis C virus (HCV) infections, and persistently normal ALT levels, after spontaneous or interferon (IFN)-induced anti-hepatitis B e (HBe) seroconversion.

METHODS

Sera from 15 patients with HBV and 13 with dual HBV-HCV infection were analyzed for the presence of HBV-DNA and HCV-RNA by polymerase chain reaction 3 yr after anti-HBe seroconversion. A total of 21 patients had seroconverted spontaneously and seven did so after IFN treatment. The core promoter and the precore regions were amplified sequenced directly.

RESULTS

Among patients with HBV infection, HBV-DNA was detected in five of nine (55%) with spontaneous anti-HBe and in all six treated patients (p = 0.092). In the coinfected patients, four had cleared both HBV-DNA and HCV-RNA, five were HBV-DNA negative/HCV-RNA positive and four had the reverse viral pattern. Among the 15 patients with persistence of HBV-DNA, a 7-base pair nucleotide deletion in the core promoter (1757-1763) was present in seven of 10 patients with spontaneous and in one of five patients with IFN-induced seroconversion (p = 0.033). The G1896A precore stop codon mutation was never observed. HBV-DNA levels were significantly lower in patients with the core promoter deletion (p = 0.011). The 7-base pair deletion generated a truncated X protein at amino-acid position 132.

CONCLUSIONS

A core promoter deletion after anti-HBe seroconversion was associated with low HBV-DNA levels, probably because of downregulation of pregenomic RNA production and truncation of the X protein. HBV-DNA persistence was a frequent event, even in the absence of active liver disease.

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.

Mechanisms of inhibition of nuclear hormone receptor-dependent hepatitis B virus replication by hepatocyte nuclear factor 3beta

The nuclear hormone receptors hepatocyte nuclear factor 4 (HNF4) and the retinoid X alpha (RXRalpha) plus the peroxisome proliferator-activated receptor alpha (PPARalpha) heterodimer support hepatitis B virus (HBV) replication in nonhepatoma cells. Hepatocyte nuclear factor 3 (HNF3) inhibits nuclear hormone receptor-mediated viral replication. Inhibition of HBV replication by HNF3beta is associated with the preferential reduction in the level of the pregenomic RNA compared with that of precore RNA. Hepatitis B e antigen (HBeAg), encoded by the precore RNA, mediates part of the inhibition of viral replication by HNF3beta. The amino-terminal transcriptional activation domain of HNF3beta is essential for the inhibition of HBV replication. The activation of transcription by HNF3 from HBV promoters downstream from the nucleocapsid promoter appears to contribute indirectly to the reduction in the steady-state level of 3.5-kb HBV RNA, possibly by interfering with the elongation rate of these transcripts. Therefore, transcriptional interference mediated by HNF3 may also regulate HBV RNA synthesis and viral replication.

Naturally occurring hepatitis B surface gene variants in chronic hepatitis B virus infection: correlation with viral serotypes and clinical stages of liver disease

Virus variants escaping from host immunity may be implicated in the pathogenesis of hepatitis B virus (HBV) infection. In this cross-sectional study, the association was evaluated of the frequency of amino acid variation within the immunogenic epitopes of surface gene with different disease stages of chronic HBV infection. The surface gene of HBV encompassing the a determinant (amino acids 124-148) and the putative HLA class I restricted cytotoxic T lymphocyte (CTL) epitope (amino acids 28- 51) were amplified and directly sequenced in 33 asymptomatic carriers (Group I), 31 patients with chronic hepatitis (Group II), 22 with cirrhosis (Group III), and 36 with hepatocellular carcinoma (Group IV). The amino acid sequences were compared subsequently with the consensus sequences of HBV serotype adw or adr. The frequency of amino acid variation per site per sequence (FEQ) was analyzed by generalized estimating equation with Poisson model after stratification by clinical and virological features. The FEQ was 1.21% overall, and was highest in Group IV patients and in patients above 50 years of age. In contrast, nine Group IV patients aged below 50 years who were infected with serotype adw had an inversely higher FEQ than those above 50; the age effect among hepatocellular carcinoma patients was significantly different from that among non-cancerous patients (P = 0.04). Variation of amino acid clustered within a determinant and CTL epitope for serotype adw but was distributed at random for serotype adr. Mutation hotspots differed between serotypes adw and adr. The FEQ of HBV surface protein is correlated positively with advancing age and severity of liver disease, and certain variants may contribute to the persistence of HBV infection.