Mutations in the pre-core region of hepatitis B virus serve to enhance the stability of the secondary structure of the pre-genome encapsidation signal

Hepatitis B virus basal core promoter mutation and DNA load correlate with expression of hepatitis B core antigen in patients with chronic hepatitis B

BACKGROUND

Expression of intrahepatic hepatitis B core antigen (HBcAg) is related to the immunopathogenesis of hepatitis B virus (HBV) infection. This study investigated the role that HBV genotype and basal core promoter (BCP) mutation play in the expression of HBcAg.

METHODS

A total of 70 hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis (genotype B in 52 patients and genotype C in 18 patients; BCP mutation T1762/A1764 in 16 patients) were enrolled. Clinical, virologic, and histologic features were compared with regard to localization and expression of intrahepatic HBcAg. The effects that HBV genotype and BCP mutation T1762/A1764 had on expression of HBcAg were further evaluated by in vitro assays.

RESULTS

Cytoplasmic, mixed cytoplasmic/nuclear, and nuclear localization of intrahepatic HBcAg was found in 38 (56.7%), 25 (37.3%), and 4 (6.0%) patients, respectively; HBcAg was not discernible in 3 patients. A total of 58 (82.9%) of these patients expressed a high level of HBcAg. In multivariate analysis, cytoplasmic localization of HBcAg correlated only with a low HBV load in serum (P = .045) and BCP mutation (P = .04). A high expression level of HBcAg also correlated with a high HBV load in serum (P = .015) and with BCP wild-type sequence (P = .037). In vitro assays indicated that the HBV BCP mutant strain had lower subcellular expression of HBcAg than did the BCP wild-type strain.

CONCLUSIONS

HBV BCP mutation and HBV load, but not genotype, contribute to the expression of intrahepatic HBcAg.

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

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

Adding interferon to lamivudine enhances the early virologic response and reversion of the precore mutation in difficult-to-treat HBV infection

BACKGROUND

The virologic impact of adding interferon to antiviral nucleoside therapy was studied in Japanese patients having perinatally transmitted hepatitis B virus (HBV) genotype C.

METHODS

Sixty-four patients including 41 positive for hepatitis B e antigen (HBeAg) were assigned to receive either (1) a combination of interferon-alpha (6 million units daily for 2 weeks, then three times weekly) plus lamivudine (100 mg daily) for 24 weeks followed by lamivudine alone for 28 weeks (n = 30) or (2) 52-week lamivudine monotherapy (n = 34).

RESULTS

The combination treatment enhanced the early virologic response, and HBV clearance was more frequent at week 8 for patients with baseline HBV DNA < or = 7 log copies/ml (90% vs. 33%, P = 0.013) and at week 24 for patients with baseline HBV DNA > 7 log copies/ml (75% vs. 40%, P = 0.080). In the combination arm, YMDD mutants emerged less often at week 52 (8% vs. 30%, P = 0.047). However, reversion of the precore mutation was more prominent with combination treatment than with monotherapy (McNemar test, P = 0.014 and P = 0.103, respectively). HBeAg seroconversion (P = 0.429) and sustained off-treatment HBV suppression to < or =5 log copies/ml (log-rank test, P = 0.195) were not improved.

CONCLUSIONS

Simultaneous commencement of treatment with interferon and a nucleoside analog may be worthy as a treatment option to augment the early virologic response and prevent drug resistance in difficult-to-treat patients. Combination treatment was also shown to enhance reversion of the precore mutation. Further studies are warranted to clarify the therapeutic implications of this phenomenon.

Clinical significance of precore and core promoter mutations in genotype D hepatitis B-related chronic liver disease

The impact of mutations in the precore and basal core promoter (BCP) regions of the hepatitis B virus on the course of chronic liver disease is not well established. We sought to examine the relationship of these characteristics to the clinical expression of liver disease in patients infected with genotype D chronic hepatitis B (CHB). BCP and precore mutations in 110 patients with genotype D1 CHB were determined and correlated with clinical phenotype. Of 110 patients, 95 (86.5%) were HBeAg-negative. Compared with HBeAg-positive subjects, HBeAg-negative patients were over a decade older and had lower viral loads (3.70 +/- 0.98 vs 5.77 +/- 0.69 log copies/ml, P < 0.001). The double mutation A1762T-G1764A was more prevalent in patients with advanced liver disease (AdLD) and was associated with higher alanine aminotransferase and viral load. After adjusting for age, there was a more than fourfold increase in the risk of AdLD with this mutation (OR = 4.4; 95% CI: 1.13-16.92, P < 0.03). Conversely, the G1757A substitution was associated with protection, being 90% less frequent among patients with AdLD (P = 0.001). The results indicate that in genotype D CHB, the presence of the A1762T-G1764A mutation was associated with more aggressive liver disease while the G1757A substitution was associated with protection from advanced disease.

A complete genomic analysis of hepatitis B virus genotypes and mutations in HBeAg-negative chronic hepatitis B in China

We aimed to study the distribution of hepatitis B virus (HBV) genotypes/subgenotypes in different parts of China and their clinical impact on the severity of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. Residual serum samples from a cohort of HBeAg-negative chronic hepatitis B patients in Hong Kong, Shanghai and Beijing were studied. Complete HBV genomic sequencing was performed for phylogenetic tree analysis and determination of HBV mutations was carried out. Mutations associated with severe liver fibrosis (Ishak score 4 or more) were selected by computerized information gain criteria. Genotype B (all subgenotype Ba) HBV was present in 19 of 45 (42%), 12 of 31 (39%) and 5 of 25 (20%) patients in Hong Kong, Shanghai and Beijing, respectively (P = 0.16). Ninety-seven per cent of genotype C HBV in Shanghai and Beijing belonged to subgenotype Ce whereas 69% of genotype C patients in Hong Kong belonged to subgenotype Cs (P < 0.001). Patients infected by subgenotype Cs had the lowest serum albumin and highest alanine aminotransferase levels compared with subgenotype Ce and Ba. Patients infected by subgenotype Cs also had more severe histological necroinflammation than subgenotype Ce. Two HBV mutations were identified to associate with severe liver fibrosis (G2858C and C2289A) and one mutation was protective against severe liver fibrosis (T2201C). The T2201C mutation was found exclusively among patients (21 of 46 patients, 45%) infected by HBV subgenotype Ce. The clinical differences in HBeAg-negative chronic hepatitis B in China may be influenced by different distribution of subgenotype C HBV.

A valine to phenylalanine mutation in the precore region of hepatitis B virus causes intracellular retention and impaired secretion of HBe-antigen

AIM

Hepatitis B virus (HBV) e antigen (HBeAg) is translated from precore mRNA as a precore/core protein, which is post-translationally modified to give rise to the protein that is secreted into the serum. The G1862T mutation in HBV occurs in the bulge of the encapsidation signal within the pregenomic RNA. When the precore mRNA is translated, this mutation results in a valine to phenylalanine substitution at the -3 position to the signal peptide cleavage site at the amino end of the precursor protein. The aim of this study was to determine whether this mutation could affect HBV replication and/or HBeAg expression.

METHODS

Following transfection of Huh 7 cells, HBV replication was followed using real time polymerase reaction (PCR) and expression of HBeAg expression was monitored using confocal microscopy.

RESULTS

HBV replication was reduced when this mutation was introduced into genotype D but not into genotype A replication-competent constructs. Using mutant HBeAg-expressing plasmids, we demonstrated a 54% reduction in HBeAg secretion relative to the wild type. Confocal microscopy demonstrated that the mutant HBeAg accumulated in the endoplasmic reticulum, endoplasmic reticulum intermediate compartment and Golgi. These aggregates of mutant protein increased in size following treatment of the cells with a proteasome inhibitor, MG132, and had the hallmark features of aggresomes. They attracted ubiquitin, heat shock proteins and proteasomes and were isolated from the cytosol by the intermediate filaments, vimentin and cytokeratin.

CONCLUSION

The formation of aggresomes, as a result of the G1862T mutation, may play a contributory role in HBV-induced liver disease.

Non-A hepatitis B virus genotypes in antenatal clinics, United Kingdom

In the United Kingdom, the National Screening Programme for identification of hepatitits B virus (HBV) infection in pregnant women uses HBV e antigen (HBeAg) and antibody to HBeAg (anti-HBe) as markers of infectivity to determine use of immunoglobulin for hepatitis B. Serum samples from 114 HBV-infected women were analyzed. Viral loads correlated with HBeAg/anti-HBe status and viral genotypes. Among 95 mothers whose serum contained anti-HBe, viral loads ranged between undetectable and 8.6 x 10(6) IU/mL (median 228 IU/mL). Ten (10.5%) of these mothers had plasma viral loads >10(4) IU/mL; 6 were infected with genotype E and one each with genotypes A, B, C, and D. All viruses had precore stop codon or basal core promoter mutations. Preponderance of genotypes other than A among antenatal mothers in the United Kingdom reflects increasing globalization and trends in immigration. HBeAg serostatus is no longer sufficiently accurate for inferring potential infectivity of pregnant HBV carriers.

Chronic HBV-related liver disease

Thirty years after its discovery, the hepatitis B virus (HBV) still remains a major global public health problem. Worldwide, two billion subjects have been infected, 300 million have a chronic infection and more than 600,000 die annually of HBV-related liver disease or hepatocellular carcinoma; new infections occur because of the presence of a large reservoir of chronic carriers of the virus. The knowledge of the HBV organization and replication cycle and the availability of sensitive HBV-DNA assays have led to remarkable progress in our understanding of the natural history of chronic hepatitis B infections. Crucial to the prevention of new infections, to the management and the monitoring of HBV carriers and to the choice of best treatment strategy, is the understanding of the natural dynamism of HBV infection and of the virus-host interactions that induce liver damage.

A pilot study of extended duration peginterferon alfa-2a for patients with hepatitis B e antigen-negative chronic hepatitis B

OBJECTIVES

Forty-eight weeks of peginterferon alfa-2a is the approved regimen for chronic hepatitis B (CHB). Standard interferon is more effective for hepatitis B e antigen (HBeAg)-negative CHB when given for longer than 1 yr. This study evaluated peginterferon alfa-2a for 60 wk, alone or in combination with lamivudine.

METHODS

Thirteen patients with HBeAg-negative CHB received peginterferon alfa-2a (180 microg/week) for 60 wk or peginterferon alfa-2a (180 microg/week) for 12 wk followed by 48 wk of peginterferon alfa-2a plus lamivudine. The primary end point, sustained virologic response (SVR), was defined as a reduction in hepatitis B virus deoxyribonucleic acid (HBV DNA) of >or=2 log10 copies/mL and HBV DNA<20,000 copies/mL at 24 wk of follow-up (week 84). Hepatitis B surface antigen (HBsAg) concentrations were analyzed and compared to changes in HBV DNA.

RESULTS

SVR was achieved by 9/13 patients (69%). At week 84, HBV DNA was undetectable by polymerase chain reaction in 5/13 (38%) patients, and 3 additional patients had a sustained 2-3 log reduction in HBV DNA. Five patients demonstrated a >90% decrease in HBsAg concentration at week 60, including 3 with undetectable HBV DNA at week 84 and a fourth who met criteria for SVR.

CONCLUSIONS

Sixty weeks of peginterferon alfa-2a with or without lamivudine resulted in a higher rate of SVR compared to historical controls with HBeAg-negative CHB treated with 48 wk of pegylated interferon. Larger studies are necessary to assess if longer duration therapy is more effective than the standard regimen and results in a greater decline in HBsAg concentration.

Mutational patterns of hepatitis B virus genome and clinical outcomes after emergence of drug-resistant variants during lamivudine therapy: analyses of the polymerase gene and full-length sequences

It remains unclear whether mutational patterns of the hepatitis B virus (HBV) genome are associated with the development of severe hepatitis after the emergence of tyrosine-methionine-aspartate-aspartate (YMDD) variants during lamivudine treatment. Thirty patients with chronic hepatitis B who had YMDD variants during lamivudine therapy and were followed up subsequently while receiving lamivudine alone for at least 6 months were examined retrospectively. The lamivudine resistant mutations in the HBV polymerase gene were detected by a line probe assay, and the full-length sequences of HBV DNA were determined in some patients. Between months 5 and 33 of therapy, mutations from methionine to isoleucine at rt204 (rtM204I) were detected in 18 patients, and mutations from methionine to valine at rt204 (rtM204V) were detected in 12. The rtM204V mutations were always accompanied by mutations from leucine to methionine at rt180 (rtL180M), while rtM204I mutations were not. Baseline characteristics, alanine aminotransferase (ALT) levels, and HBV DNA levels within 6 months after the emergence of YMDD variants did not differ significantly between patients with rtM204I alone and those with rtL180M/rtM204V. No specific mutation was identified on full-length sequence analysis in three patients with a hepatitis flare. During long term follow-up, the addition of rtL180M to rtM204I was found in four patients 7-31 months after detecting the change at rt204 and was linked to increased ALT levels. In conclusion, mutational patterns of HBV DNA at the time of emergence of YMDD variants were apparently unrelated to the clinical outcomes in Japanese patients with chronic hepatitis B during lamivudine therapy.

Hepatitis B virus DNA prediction rules for hepatitis B e antigen-negative chronic hepatitis B

After hepatitis B e antigen (HBeAg) seroconversion, hepatitis B may become inactive or progress to HBeAg-negative hepatitis with persistent or intermittent alanine aminotransferase (ALT) elevation. The aim of this study was to prospectively identify factors predictive of the clinical course in HBeAg-negative chronic hepatitis B (CHB). Patients were stratified by ALT and HBeAg status and followed every 3 months for up to 5 years. Kaplan-Meier and Cox regression analysis using the change from normal ALT to elevated ALT as endpoints were performed to determine factors associated with ALT elevation/normalization. Seventy-four HBeAg-negative and 32 HBeAg-positive patients were prospectively evaluated. For HBeAg-negative patients, hepatitis B virus (HBV) DNA was predictive of future ALT. Only 1 patient with normal ALT and an HBV DNA value lower than 10,000 copies/mL developed an elevated ALT within the subsequent year, whereas 67% with an HBV DNA value greater than 100,000 copies/mL had a rise in ALT above normal within 1 year. Patients with a previous history of ALT elevation and longer follow-up at all levels of HBV DNA were more likely to experience ALT elevations. For HBeAg-negative patients with elevated ALT and all HBeAg-positive patients, HBV DNA did not predict future ALT. Other viral and host factors were not predictive of future ALT.

CONCLUSION

HBeAg-negative CHB has a fluctuating course. HBV DNA values lower than 10,000 copies/mL predict persistently normal ALT for at least 1 year. Patients with HBV DNA values between 10,000 and 100,000 copies/mL can safely be followed at 6 monthly intervals, whereas HBV DNA values greater than 100,000 copies/mL are highly predictive of future ALT elevation and should prompt regular follow-up.

Subgenotypes of hepatitis B virus genotype C do not correlate with disease progression of chronic hepatitis B in Taiwan

BACKGROUND

Hepatitis B virus (HBV) genotype C (HBV/C) has two subgenotypes: HBV/Cs and Ce. The prevalence and clinical implications of subgenotype Cs and Ce in Taiwanese HBV carriers remain unknown.

METHODS

Subgenotypes of HBV/C were determined in 242 Taiwanese HBV carriers with various stages of liver disease. The clinical as well as virologic features between patients with HBV/Cs and HBV/Ce infection were further compared.

RESULTS

HBV/Ce was the predominant subgenotype in Taiwan. The prevalence of HBV/Ce was 93.6% in the inactive carriers group, 84.2% in chronic hepatitis patients, 81.2% in cirrhosis patients, 92.5% in hepatocellular carcinoma (HCC) patients without cirrhosis and 91.9% in HCC patients with cirrhosis. There was no significant difference in the distribution of the HBV/C subgenotypes among patients with different stages of liver disease.

CONCLUSIONS

Subgenotypes of HBV/C may not have a clinical impact on the disease progression of chronic hepatitis B in Taiwan.

Genetic characteristics of hepatitis B virus genotypes as a factor for interferon-induced HBeAg clearance

The factors determining the responsiveness of different hepatitis B virus (HBV) genotypes to interferon treatment are not fully understood. We investigated the relationship between HBV genetic characteristics and the outcome of short (16 weeks) or prolonged (32 weeks) treatment with standard interferon-alpha in a prospectively followed cohort of 103 patients across Europe with HBeAg positive chronic hepatitis B. INNO-LiPA assays and HBV DNA sequencing were used to determine HBV genotypes, mutations in the core promoter and precore/core regions. After 16-weeks interferon-alpha treatment, the rate of HBeAg clearance was higher in genotype A versus all other genotypes (P = 0.014), or genotype D alone (P = 0.05). The HBV genome analysis revealed that: (i) after 16-weeks treatment, an HBV subpopulation with core promoter mutations emerged or increased (P < 0.001) only in genotype A; (ii) the core gene of genotype A has the lowest number of amino acid variations in comparison with genotypes B, C, or D. Logistic regression analysis identified genotype A as a positive predictor of short (16 weeks) treatment response (P = 0.001; odds ratio 6.19, 95 confidence interval 1.94-19.8), having a greater impact than baseline HBV DNA or alanine aminotransferase (ALT) levels. In contrast, the response to prolonged interferon-alpha treatment was not different between HBV genotypes. These results suggest that HBV genotype A responds earlier to interferon treatment than other genotypes, which is associated with its molecular characteristics. The optimal duration of interferon-based therapies in chronic hepatitis B may vary between different HBV genotypes.

Natural history of hepatitis B virus infection: an update for clinicians

Hepatitis B virus (HBV) is a common viral pathogen that causes a substantial health burden worldwide. Significant progress has been made in the past few decades in understanding the natural history of HBV infection. A dynamic balance between viral replication and host immune response is pivotal to the pathogenesis of liver disease. In immunocompetent adults, most HBV infections spontaneously resolve, whereas in most neonates and infants they become chronic. Those with chronic HBV may present in 1 of 4 phases of infection: (1) in a state of immune tolerance, (2) with hepatitis B e antigen (HBeAg)positive chronic hepatitis, (3) as an inactive hepatitis B surface antigen carrier, or (4) with HBeAg-negative chronic hepatitis. Of these, HBeAg-positive and HBeAg-negative chronic hepatitis may progress to cirrhosis and its long-term sequelae including hepatic decompensation and hepatocellular carcinoma. Several prognostic factors, such as serum HBV DNA concentrations, HBeAg status, serum aminotransferases, and certain HBV genotypes, have been identified to predict long-term outcome. These data emphasize the importance of monitoring all patients with chronic HBV infection to identify candidates for and select optimal timing of antiviral treatment, to recognize those at risk of complications, and to implement surveillance for early detection of hepatocellular carcinoma.

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

BACKGROUND/AIMS

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Hepatitis B virus genotypes in Europe

There are eight genotypes of hepatitis B virus (HBV). Most genotypes can be further divided into subgenotypes. HBV genotypes influence the course of disease and treatment, and show geographic preferences. In Europe, A and D are the main genotypes found. Genotype A is more prevalent in northern Europe, where genotype D is mainly found in countries surrounding the Mediterranean Sea and in Eastern Europe. Subgenotype A2 is the dominant subgenotype in Europe, but the geographic prevalence of the four subgenotypes found in genotype D is not yet clear. On treatment with interferon HBV, genotype A, compared to genotype D, showsbetter virological response and in a large proportion of patients, even development of anti-HBs. However, in the first year of treatment with lamivudine, higher rates of emergence of YMDD variants are observed in genotype A. This work summarizes the current knowledge on HBV genotypes in countries with low and intermediate HBV carriership from Europe.

Impact of viral genotypes and naturally occurring mutations on biological properties of hepatitis B virus

Hepatitis B patients worldwide are infected with different viral genotypes. Within the same individual the dominant viral species evolves over the course of chronic infection to generate viral variants or mutants. The mutations, often selected by the host immune response or antiviral therapy, are sometimes restricted by viral genotypes. We are interested in characterizing mutations that affect the expression of hepatitis B e-antigen (HBeAg), a protein with a large effect on duration of infection and severity of liver diseases. HBeAg is encoded by the precore region in addition to the core gene. Core promoter mutations reduce HBeAg expression at the transcriptional level. We found that the hot spot mutations (A1762T/G1764A) only mildly reduced HBeAg expression and enhanced genome replication, while incorporation of additional core promoter mutations intensified both phenotypes. At the step of translation, a G1896A nonsense mutation in the precore region abolishes HBeAg expression. We first reportedthat the G1896A mutation rarely occurred in genotype A. Subsequent studies by others established the role of polymorphism at nucleotide 1858, rather than genotype, as the determinant for the G1896A mutation. Conversion of the precore/core protein to HBeAg requires proteolytic removal of both the amino and carboxy termini, and a (151)RRGR(154) motif has been implicated as the carboxy terminal cleavage site. In this regard, genotype A is unique in possessing a dipeptide insertion that expands the motif into (151)RRDRGR(156). We found that genotype A is cleaved primarily at R156, generating a mature HBeAg that is two amino acids longer than HBeAg from other genotypes. There are different avenues whereby HBeAg expression or its antigenicity can be modulated by viral genotype and naturally occurring mutations.

Changes in viral loads of lamivudine-resistant mutants during entecavir therapy

AIM

Entecavir therapy is effective against lamivudine-resistant virus in patients with hepatitis B virus infection. We investigated viral load changes of YMDD mutant virus (rtM204I [YIDD sequence], rtM204V [YVDD]) in serial serum samples during entecavir treatment for lamivudine-resistant virus and determined changes in viral precore and core promoter mutants.

METHODS

Nineteen patients were treated in randomized, double-blind phase II clinical trials of entecavir at 0.5 or 1.0 mg for breakthrough hepatitis due to lamivudine-resistant virus. Viral changes in YMDD mutants (rtM204I, rtM204V), amino acid changes in the polymerase reverse transcriptase region and precore/core promoter mutations at 52 weeks were determined in 18 patients.

RESULTS

Changes in viral loads of rtM204I and rtM204V were similar. No differences in load changes were seen betweenthe 0.5 and 1.0 mg groups. However, load changes for rtM204I alone were greater than those for the rtM204I + rtM204V mixed-type (P = 0.042, at both 40 and 52 weeks). Load changes in rtM204I and rtM204V with G1896A tended to be greater than those without. Moreover, G1896A was replaced by wild-type virus in two patients at 52 weeks.

CONCLUSION

RtM204I only or the existence of precore mutation was more sensitive to entecavir therapy against lamivudine-resistant virus.

Hepatitis B virus (HBV) genotypes/subgenotypes in China: mutations in core promoter and precore/core and their clinical implications

BACKGROUND

The association of hepatitis B virus (HBV) genotypes with clinical course of infection is increasingly recognized.

OBJECTIVES

In order to investigate the genetic diversity of HBV and its clinical implications, 241 HBV-infected patients including 34 with hepatocellular carcinoma (HCC) were enrolled in this study.

METHODS

HBV genotyping was performed with an ELISA assay. HBV subgenotypes were determined by PCR-RFLP. HBV core promoter/precore/core mutations were analyzed by direct sequencing.

RESULTS

The overall prevalence of HBV/B and C was 65% and 33%, respectively. Among HBV/C, 42% were Cs/C1 and 58% were Ce/C2. The HBV/C1 was only found in the patients originating from Southern China (p=0.0001). Among HCC patients, HBV/C2 was only found in the elder age group (> or =51 years; p<0.05) and HBV/Ba was associated with young HCC patients (<35 years). Mutations associated with HCC were V1753 and T1762/A1764 (p<0.01). The prevalence of the V1753 was higher in HBV/C1 strains (p<0.04), A1898 was only found among HBV/C1 (p=0.056). T1762/A1764 was frequently demonstrated in both subgenotypes. The T1858 (90%) and A1896 (40%) mutations were most frequent in HBV/C2 (p<0.008).

CONCLUSIONS

HBV/C1 and HBV/C2 have distinct geographic distributions in China. V1753 in addition to T1762/A1764 double mutation in the basal core promoter region seems to be associated with HCC development, especially in the patients with HBV/C1.

Clinical and virological characteristics of hepatitis B virus subgenotypes Ba, C1, and C2 in China

Hepatitis B virus (HBV) subgenotypes Ba, C1 (Cs), and C2 (Ce) are the most prevalent HBV variants in China. To investigate the virological characteristics of these subgenotypes and their clinical implications, we enrolled a cohort of 211 patients in the Guangdong Province of China, including 132 with chronic hepatitis B virus infection (CH), 32 with liver cirrhosis (LC), and 47 with hepatocellular carcinoma (HCC) according to clinical examination, liver function test, and ultrasonograph results. Overall, HBV Ba was found in 51.2% (108/211), HBV C1 in 33.6% (71/211), and HBV C2 in 15.2% (32/211) of the cases. The distribution of HBV genotype C was greater among patients in the LC and HCC groups than among patients in the CH group, while the distribution of HBV genotype B was greater among the CH patients than among the LC and HCC patients. No significant differences in clinical features were found among patients with HBV Ba, C1, and C2. Virologically, HBV C1 had the strongest association with the A1762T G1764A double mutation, while the mutation at position 1896 resulting in A (1896A) was uncommon. In contrast, HBV Ba had the highest frequency of 1896A but the lowest of A1762T G1764A, and HBV C2 had intermediate frequencies of these mutations. Mutations of 1653T and 1753V were specifically associated with HBV C2 and C1, respectively. Multivariate analyses showed that the 1653T, 1753V, and A1762T G1764A mutations and patient age significantly increased the risk of HCC development. In conclusion, HBV Ba, C1, and C2 have different mutation patterns in the enhancer II/core promoter/precore region. Therefore, genotyping and detecting the 1653T and 1753V mutations, in addition to the A1762T G1764A double mutation, might have important clinical implications as predictive risk factors for hepatocarcinogenesis.

Initial load of hepatitis B virus (HBV), its changing profile, and precore/core promoter mutations correlate with the severity and outcome of acute HBV infection

BACKGROUND

The pathogenesis of the fulminant or severe form of acute hepatitis B virus (HBV) infection remains unclear, although both host- and virus-specific factors are considered to have a great impact on the c course. We aimed to define possible viral factors implicated in the severe form of acute HBV infection.

METHODS

We investigated viral factors in 42 patients with acute HBV infection: 11 had fulminant hepatitis (FH); 9 had a severe form of acute hepatitis (SAH), defined as having a prothrombin activity of less than 40% without encephalopathy; and 22 had acute self-limited hepatitis (AH).

RESULTS

Although there was no significant difference in serum HBV DNA levels on admission among the three groups, the level decreased more rapidly in patients with SAH or FH than in those with AH. In patients with SAH or FH, the HBV load on admission was higher in patients who died than in those who recovered (7.0 +/- 1.6 vs 5.6 +/- 1.0 log copies/ml; P=0.0293). In univariate analysis, seronegativity for hepatitis B envelope antigen (HBeAg) and mutations in both the precore (G1896A and/or G1899A) and core promoter (T1753A/C and/or T1754C/G and/or A1762T/G1764A) were associated with FH (odds ratio [OR], 5.60; P=0.0269 and OR, 52.0; P=0.0006; respectively). In multivariate logistic regression analysis, only the presence of precore/core promoter mutations was associated with FH (OR, 42.8; P=0.0020).

CONCLUSIONS

The rapid decrease in viral load in the early phase of acute HBV infection was associated with the severity of the disease. A high viral load on admission and the presence of both precore and core promoter mutations in patients with severe coagulopathy closely correlated with mortality.

Molecular epidemiological study of hepatitis B virus infection in two different ethnic populations from the Solomon Islands

The Solomon Islands is a multi-ethnic nation with a high rate of hepatitis B virus (HBV) infection. The prevalence relative to ethnicity was examined in relation to HBV infection, genotypes, and mutations. Asymptomatic populations (n = 564, 308 Melanesian and 118 Micronesian) from the Western Province were enrolled. Positive samples for Hepatitis B surface antigen (HBsAg) were examined for serological status, genotyping, viral load, and mutations of the basic core promoter (BCP) and pre-core (Pre-C) regions. The positive rate for HBsAg was 21.5%. The major Melanesian genotype was C (HBV/C), whereas the major Micronesian genotype was D (HBV/D). The prevalence of Hepatitis B e antigen (HBeAg) in serum was lower in carriers of HBV/D than of HBV/C. While the prevalence of the BCP mutation (T(1762)A(1764)) tended to be higher in HBV/C, that of the Pre-C mutation (T(1846)) was significantly higher in HBV/D (P < 0.0001). Genetic distance and phylogenetic analyses based on complete genome sequences were also carried out for two strains of HBV/C and two strains of HBV/D, and the findings were compared with those in the DDBJ/EMBL/GenBank database. The full-length sequence revealed that strains from the Solomon Islands were classified into subgenotype C3 (HBV/C3) and D4 (HBV/D4), and that the HBV/D strains were related closely to those from Papua New Guinea. HBV infection in the Solomon Islands is hyperendemic, and the genotype is ethnicity-specific. HBeAg appears to clear from the serum in young adulthood in HBV/D infection, which may be influenced by genotype-dependent features in relation to viral mutations.

Correlation of hepatitis B virus (HBV) genotypes and mutations in basal core promoter/precore with clinical features of chronic HBV infection

BACKGROUND/AIMS

To investigate the correlation of hepatitis B virus (HBV) genotypes and basal core promoter (BCP) and precore (PC) mutations in patients with chronic hepatitis B.

METHODS

HBV genotyping, nucleotide mutation, serum HBV DNA level and serological markers were analyzed in 121 patients with chronic HBV infection using INNO-LiPA HBV genotyping, polymerase chain reaction (PCR) product-based sequencing, fluorescence quantitative PCR and enzyme-linked immunosorbent assays respectively.

RESULTS

Forty (33.0%), 77 (63.6%), two (1.7%) and two (1.7%) patients had genotypes B, C, B/C and D infections respectively. Significant differences were found in serum HBV DNA levels (log10 copies/ml: 6.18 vs. 5.61, P=0.042) and mutations at nucleotide (nt) 1762/1764 (71.4% vs. 42.5%, P=0.002) between genotypes C- and B-infected patients. There were significant differences in the mean age, serum biochemical parameter levels and mutation rates in BCP/PC among hepatitis e antigen (HBeAg)-positive and -negative chronic hepatitis B (CHB) and liver cirrhosis (LC) groups.

CONCLUSION

Genotypes C and B are predominant in China, and the frequent nt 1762/1764 mutation, which occurs commonly in HBeAg-negative CHB, especially in genotype C patients, may be associated with the progress of chronic HBV infection.

Prevalence of hepatitis B virus genotype D in precore mutants among chronic liver disease patients from New Delhi, India

Hepatitis B is one of the most important causes of chronic viral hepatitis world wide. Mutations in the precore region of the hepatitis B virus (HBV) genome are frequently found in hepatitis B envelope antigen-negative cases. Data from India on the HBV genotype-associated distribution of precore mutations are limited. Our objective in this study was to genotype and detect the precore mutant with a point mutation from G to A at nucleotide 1896 using ligase chain reaction (LCR) and direct sequencing. A total of 115 cases of chronic liver disease were screened. The cases were evaluated on the basis of history, clinical examination, liver function profile, and serological test for HBV infection, which includes HBsAg, anti HBcIgG, HBeAg using commercially available ELISA kits. The cases, which were HBeAg+, HBeAg-, and HBV DNA+, were subjected to LCR and confirmed by direct sequencing. Of 115 chronic liver disease cases, 50 (43.5%) cases were HBV DNA positive. All cases were subjected to LCR; 11 (22%) cases confirmed the presence of precore mutants, while the remaining 39 (78%) were classified as the wild form of the virus. HBV genotyping by direct sequencing revealed that genotype D was predominant in both wild and mutant forms of the virus. We conclude that the HBV genotype distribution was not significantly different between precore mutants and the wild form of the virus (P>0.05). North Indian patients with genotype D were more likely to have persistent HBV infection with precore mutants. HBV genotypes correlate with the clinical outcome of chronic HBV infection.

Low replication and variability of HBV pre-core in concomitant infection with hepatitis B and hepatitis C viruses

In an attempt to define the virological profile of HBV in HCV co-infection, we analysed the viral load, the infecting genotype, and the mutational pattern of the HBV pre-core region (pre-C), which is involved in viral encapsidation and DNA replication. Eighty-six patients were studied: 32 with serological HBV/HCV-1b co-infection (group BC), 32 infected by HBV alone (group B), and 22 by HCV-1b alone (group C). Sequence analysis of the HBV pre-S and pre-C regions identified genotypes and mutational patterns. The HBV viral load was significantly lower in group BC than in group B (p < 0.001), and the distribution of HBV pre-C mutations showed a higher prevalence of wild type in concomitant infection than in the control group (p < 0.006). The predominant HBV infecting strain was genotype D in both the BC (96%) and B (87%) groups. No difference was observed in HCV viremia levels between the two groups, whereas in HBV/HCV infection, the low levels of circulating HBV were closely associated with the low degree of variability of pre-C domain (p = 0.005). In conclusion, in HBV/HCV infection, the virological pattern was characterised by the dominance of HCV associated with lower HBV replication capacity and decreased emergence of HBV pre-C variants.

In vitro study of the effects of precore and lamivudine-resistant mutations on hepatitis B virus replication

Understanding the consequences of mutation in the hepatitis B virus (HBV) genome on HBV replication is critical for treating chronic HBV infection. In this study, HBV replication in HepG2 cells initiated by transduction with precore (PC), rtM204I, and wild-type (wt) HBV recombinant baculoviruses was compared. The pattern and magnitude of HBV replication initiated by the PC HBV recombinant baculovirus were similar to those observed for wt HBV throughout the time course examined. In contrast, when the rtM204I mutation was introduced into wt HBV, by day 10 postinfection the levels of intra- and extracellular HBV DNA were markedly reduced compared to those for wt HBV. Although the rtM204I mutation reduced the production of HBV replicative intermediates, no effect on the level of covalently closed circular DNA or HBV transcripts was observed at late time points. Coinfection studies with different ratios of wt and rtM204I baculoviruses showed that the rtM204I variant did not produce a product that inhibited HBV replication. However, the combination of the wt and rtM204I baculoviruses yielded HBV DNA levels at late time points that were greater than those for the wt alone, suggesting that wt polymerase may function in trans to boost rtM204I replication. We concluded that the rtM204I mutation generates a polymerase that is not only resistant to lamivudine but also replicates nucleic acids to lower levels in vitro.

Hepatitis B virus replication

Hepadnaviruses, including human hepatitis B virus (HBV), replicate through reverse transcription of an RNA intermediate, the pregenomic RNA (pgRNA). Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription: it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA, ε, as template, and depends on cellular chaperones; moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids. This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV (DHBV), now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cell-free systems. At this time, they can, unfortunately, not be complemented by three-dimensional structural information on the involved components. However, at least for the ε RNA element such information is emerging, raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal, will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.

Hepatitis B virus genotypes and precore/core-promoter mutations in Tunisian patients with chronic hepatitis B virus infection

OBJECTIVE

The aim of this study was to determine the frequency of genotype and precore/core-promoter mutations in chronic hepatitis B virus (HBV) infected individuals in Tunisia.

METHODS

We studied 164 Tunisian patients (38 HBeAg-positive and 126 HBeAg-negative) with chronic HBV infection. Genotypes and precore/core-promoter mutations were studied using Inno-LiPA and Multiplex-PCR and PCR-RFLP methodology.

RESULTS

Alanine aminotransferase (ALT) levels were higher in HBeAg-positive compared with HBeAg-negative patients (p<0.05). Patients with HBeAg-positive chronic hepatitis B were younger than HBeAg-negative chronic hepatitis B patients. The 164 genotypes were distributed as follows: 1 genotype A (0.6%), 1 genotype B (0.6%), 3 genotype C (1.82%), 139 genotype D (84.75%), and 20 mixed genotypes (12.2%). In the precore region (41.5%) of the patients had exclusively PC mutant and (50.9%) had a mixture of wild-type and variant sequences. PC variant was more commonly found in HBeAg-negative patients than in HBeAg-positive patients (94.5% vs. 87.8%), respectively. The mutations in the core promoter were more common in HBeAg-negative patients (65.4%) than in HbeAg-positive patients (18.2%). These results indicate that genotype D is predominant in Tunisia. Precore mutation occurred invariably among HBeAg-positive and HBeAg-negative patients, whereas core-promoter mutations were more frequently found in HBeAg-negative patients.

CONCLUSION

Analysis of these mutants may prove useful for clinical evaluation and choice of therapy.

Virological analysis, genotypes and mutational patterns of the HBV precore/core gene in HBV/HCV-related hepatocellular carcinoma

We investigated the replicative profile of hepatitis B (HBV) and hepatitis C (HCV) viruses and the mutational pattern of the HBV precore/core (pre-C/C) domain in hepatocellular carcinoma (HCC). Thirty-eight consecutive patients with HCC were included in the study - 18 of them with HBV/HCV co-infection and 20 with HBV single infection. Twenty-three additional patients with co-infection, without HCC were recruited as the control group. Replication activity was evaluated by detecting and quantitating both HBV and HCV genomes. The HBV pre-C/C region, encompassing the pregenome encapsidation signal involved in viral replication, was analysed by direct sequencing. HBV viraemia levels were significantly lower (P = 0.04) in patients with co-infection in comparison with single-infected HCC, whereas two different HBV viraemia profiles were detected in co-infection with or without circulating HCV. HBV genotype D was prevalent in the three groups and HCV genotype 1b was found to be the infecting strain in all patients. Lower variability in the pre-C/C region was found in co-infection in comparison with HBV single infection (P = 0.0004). A synonymous T1936C mutation was found in all co-infected HCC cases not related to the presence or absence of circulating HCV, and a hypermutated pre-C strain, characterized by the same mutational pattern, was identified in three HCC cases. The mutational pattern of the pre-C/C region was closely related to HBV replication efficiency, and specific HBV mutations selectively associated with HCV co-infection could be linked with accelerated HBV/HCV-related disease progression.

Basal core promoter, precore region mutations of HBV and their association with e antigen, genotype, and severity of liver disease in patients with chronic hepatitis B in India

Spontaneous mutations of hepatitis B virus (HBV) could influence the severity of liver disease. Since the basal core promoter (BCP) and the precore (Pc) regions are important for viral replication, these regions were examined for naturally occurring mutations and were correlated with the genotype, e antigen status, and severity of liver disease. In 82 patients with histologically confirmed chronic hepatitis B, the BCP and Pc regions were sequenced and aligned with known wild-type sequences. Sequence based HBV genotyping was done and HBV DNA was quantified. Thirty-three (40%) patients had decompensated chronic liver disease and the remaining patients had chronic hepatitis B. Forty-six (56%) patients were HBeAg positive. HBV genotype A was found in 28%, D in 65%, and B/C in 7.3%. The Pc G1896A mutation was more common in HBeAg-negative (33% vs. 2%, P < 0.01) patients and was genotype D specific. The Pc G1862T mutation was detected more often in HBeAg-positive than HBeAg-negative (37% vs. 11%, P < 0.01) patients and was genotype A specific (P < 0.01). BCP mutations at the 1,762/64 nucleotide positions were common in HBeAg negative than positive (36% vs. 13%, P < 0.05) and were equally common in different genotypes. TA 1-3 region mutations of the BCP were significantly higher in HBeAg-negative as compared to HBeAg-positive patients (78% vs. 26%, P < 0.01). BCP mutations had significantly higher HBV DNA levels. It is concluded that Pc G1862T mutant is Genotype A-specific but is not always associated with e antigen. The TA 1-3 rich mutations of BCP region are also associated with the absence of e antigen in Indian patients.

Genetic variability in the precore and core promoter regions of hepatitis B virus strains in Karachi

BACKGROUND

Hepatitis B virus (HBV) genotypes have distinct geographic distribution. Moreover, much genetic variability has been described in the precore (PC) and basal core promoter (BCP) regions of the HBV genome. The local prevalence of HBV genotypes and mutations has not been well studied. The aim of the present study is to determine the prevalence of HBV genotypes and mutations in the PC and BCP region in HBV strains in Karachi.

METHODS

A total of 109 chronic hepatitis B patients with detectable HBV DNA by a PCR assay were enrolled in the study. Sera were tested for HBeAg, anti-HBe antibody and liver profile. HBV genotypes and mutations in the PC and BCP regions were detected by INNO-LiPA line-probe assays.

RESULTS

Of the 109 patients investigated, 38 (35%) were HBeAg positive while 71 (65%) were HBeAg negative. Genotype D was present in 100% of the patients. Two patients had co-infection with genotype A. There was no significant difference in the baseline characteristics, mean ALT levels, and presence of clinical cirrhosis in patients with HBeAg positive or negative strains with or without PC and BCP mutations. Of the 38 HBeAg positive patients, 9 (24%) had PC and BCP mutations. In the HBeAg negative patient group, mutations were detected in 44 (62%) of the strains investigated. More than one mutation was common, seen in 26 (37%) patients with HBeAg negative disease and 6 (16%) patients with HBeAg positive disease. Twelve (17%) HBeAg negative patients had dual T1762 and A1764 mutations. None of the HBeAg positive patients had T1762 mutation. Mutations were undetectable in 27 (38%) of patients with HBeAg negative disease.

CONCLUSION

Our study shows that type D is the main HBV genotype in Karachi, Pakistan. Significant numbers of patients infected with this genotype have PC and BCP variants. Mutations at more than one site are common. Patients harboring these mutants do not differ significantly in their clinical presentation from patients having wild type infection.

Genotyping Hepatitis B virus from whole- and sub-genomic fragments using position-specific scoring matrices in HBV STAR

Hepatitis B virus (HBV) genomes have been classified into eight genotypes based on phylogenetic analysis of sequence variation. Identifying and tracking the movement of HBV genotypes is important in terms of both monitoring infection rates and predicting disease and treatment. An HBV genotyping tool has been developed that compares query sequences with position-specific scoring matrices representing the eight HBV genotypes. This tool (hbv star) is rapid, robust and accurate and assigns genotype based on a statistically defined scoring model. hbv star confidently assigned 90% of 590 full-length HBV genomes to an HBV genotype (Z score >2.0). Thirty-two of the residual 48 sequences were identified as non-human primate viruses and 16 sequences were identified as recombinant or putative recombinants. Receiver-Operated Characteristic (ROC) analysis was used to compare the accuracy of genotype prediction using basal core promoter sequences and surface and core genes with the accuracy achieved by using full-length sequences. A web interface to hbv star is available at http://www.vgb.ucl.ac.uk/starn.shtml.

Mutations affecting the replication capacity of the hepatitis B virus

The genetic variability of the hepatitis B virus (HBV) encounters two compounding forces: a high viral copy number produced during active replication and the lack of proofreading activity in the HBV polymerase, resulting in a high mutational rate. A large pool of quasispecies is generated in which the fittest virus, i.e. the virus that replicates best, becomes the dominant species. Immune and antiviral selection pressures result in vaccine/immunoglobulin escape mutants and antiviral resistant variants. Viruses encoding changes associated with antiviral resistance often have reduced replication in vitro, but the accumulation of additional mutations helps restore viral fitness. These compensatory mutations may occur not only in the polymerase gene but also in other genes such as the overlapping envelope gene, the precore gene, or in regulatory regions such as the basal core promoter. In this report we aim to review the new findings that have appeared in recent months.

Phylogenetic, virological, and clinical characteristics of genotype C hepatitis B virus with TCC at codon 15 of the precore region

Hepatitis B virus (HBV) with T-1856 of the precore region is always associated with C-1858 (i.e., TCC at nucleotides 1856 to 1858), and it is reported only in genotype C HBV isolates. We aimed to investigate the phylogenetic, virological, and clinical characteristics of HBV isolates bearing TCC at nucleotides 1856 to 1858. We have previously reported on the presence of two major subgroups in genotype C HBV, namely, HBV genotype Cs (Southeast Asia) and HBV genotype Ce (Far East). We have designed a novel 5' nuclease technology based on the nucleotide polymorphism (C or A) at nucleotide 2733 to differentiate the two genotype C HBV subgroups. The mutations at the basal core promoter and precore regions were analyzed by direct sequencing. Among 214 genotype C HBV-infected patients, 31% had TCC, 37% had CCC, 3% had CTC, and 29% had CCT at nucleotides 1856 to 1858. All except one HBV strain with TCC at nucleotides 1856 to 1858 belonged to subgroup Cs, which has been reported only in Hong Kong; Guangzhou, China; and Vietnam. HBV with TCC at nucleotides 1856 to 1858 was associated with the G1898A mutation (64%). Patients infected with HBV harboring TCC had more liver cirrhosis than those infected with HBV harboring CCC (18% versus 5%; P = 0.008), and more of the patients infected with HBV harboring TCC were positive for HBeAg (58% versus 36%; P = 0.01) and had higher median alanine aminotransferase levels (65 IU/liter versus 49 IU/liter; P = 0.006); but similar proportions of patients infected with HBV harboring TCC and those infected with HBV harboring CCT had liver cirrhosis (18% versus 13%; P = 0.43). In summary, we report that HBV with TCC at nucleotides 1856 to 1858 of the precore region might represent a specific HBV strain associated with more aggressive liver disease than other genotype C HBV strains.

Hepatitis B virus genotypes and G1896A precore mutation in 486 Spanish patients with acute and chronic HBV infection

This study aims to determine the prevalence of hepatitis B virus (HBV) genotypes (A-F) and their association with the G1896A precore mutation in 486 patients positive for HBV surface antigen. Genotypes were determined by RFLP and precore mutation by real-time PCR. Genotypes D (48.1%) and A (39.5%) were the most common, followed by F (4.1%) and B, C and E (<1%). The A to D ratio (A:D) was 1.4 in HBeAg+ chronic hepatitis B (CHB), 0.6 in HBeAg- CHB and 1.4 in HBeAg- inactive carriers. Distribution of these genotypes was different between HBeAg+ CHB and HBeAg- CHB (P = 0.02), and between HBeAg- CHB and HBeAg- inactive carriers (P = 0.009). Genotype A was the most prevalent in HBeAg+ CHB with elevated alanine aminotransferase (ALT) (68.6%) and genotype D in HBeAg+ CHB with fluctuating ALT (60.7%). There was a difference in genotype prevalence between chronic and acute infection (P = 0.03). The precore mutant correlated with high levels of HBV-DNA in genotype d HBeAg- CHB. Genotype D is not as highly prevalent in Spanish patients as would be expected in a Mediterranean area. The unequal prevalence of genotypes between acute and chronic infection suggests that genotype A is associated with a higher tendency to cause chronic infection.

Association of core promoter/precore mutations and viral load in e antigen-negative chronic hepatitis B patients

Apart from core promoter A1762T/G1764A and precore G1896A mutations, other hepatitis B virus (HBV) mutants are detected in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). The aim of this study was to determine the effects of those mutants on clinical manifestation and viral loads of genotypes B and C HBV. Seventy-nine HBeAg-negative CHB patients with hepatitis flare were enrolled in this study and their HBV precore/core region were sequenced. Serial biochemical profiles and viral loads were assessed and compared. Fifty-three patients (67%) were infected by genotype B HBV and 26 (33%) were infected by genotype C HBV. The clinical manifestation and HBV viral loads were comparable between the two groups. However, genotype B was significantly associated with precore G1896A mutation (92.5%), and more mutations within nucleotide 1809-1817 were detected in patients infected by genotype B as compared with those infected by genotype C (18.9%vs 3.8%). Most of the cases had mutations at the -2, -3 or -5 position from the precore AUG initiation codon. Triple core promoter mutations T1753C/A1762T/G1764A [corrected] appeared to be linked to genotype C rather than genotype B HBV (19.2%vs 1.9%; P = 0.013). In multivariate analysis, the presence of either triple core promoter 1753/1762/1764 mutation or nucleotide 1809-1817 mutation was the only factor associated with lower HBV viral load (<70 Meq/mL) (odds ratio = 9.01; 95% CI 1.11-71.43; P = 0.04). In conclusion, minor HBV variants with mutations in the core promoter and precore region were detectable in genotypes B and C. Such HBV variants are genotype specific and related to viraemia levels.

Genotypes and viremia of hepatitis B and D viruses are associated with outcomes of chronic hepatitis D patients

BACKGROUND & AIMS

Genotypes and viremia of hepatitis D virus (HDV) and hepatitis B virus (HBV) may be associated with outcomes. This study evaluated the impact of viral genotypes and viremia on outcomes of dual HBV and HDV infection.

METHODS

Viremia and viral genotypes were analyzed in 194 consecutive chronic hepatitis B patients with HDV superinfection and correlated with outcomes.

RESULTS

The numbers of HBV genotype A, B, C, and nonclassified were 4, 57, 23, and 110, respectively. There were 51 genotype I HDV, 74 genotype II HDV, 8 genotype IV HDV, and 61 nonclassified HDV genotype. In a median follow-up of 135 months, 24 progressed to cirrhosis and 41 developed hepatocellular carcinoma. Patients infected with genotype I HDV had a lower remission rate (15.2% vs 40.2%; P = .007) and more adverse outcomes (cirrhosis, hepatocellular carcinoma, or mortality) (52.2% vs 25.0%; P= .005) than those with genotype II HDV. Patients infected with genotype C HBV had a lower remission rate (0 vs 32.1%; P = .005) and more adverse outcomes (70.0% vs 33.9%; P = .005) than those with genotype B HBV. The presence of HBV or HDV viremia was associated with lower remission rates compared with those negative for both (26.4% and 24.3% vs 69.2%; P < .001). In multivariate analysis, age, genotype C HBV, and genotype I HDV were independent factors associated with adverse outcomes.

CONCLUSIONS

In chronic HBV and HDV dual infections, older age, genotype I HDV, and genotype C HBV correlated with adverse outcomes.

The clinical virology of hepatitis B

Hepatitis B virus (HBV) is a major human health problem as approximately 8% of the world’s population are chronic carriers and there are over a million HBV-related deaths annually. Treatment of HBV is extremely difficult, as the unique viral replication strategy results in both a continual source of stable DNA molecules that are the template for viral replication and gene expression, and a pool of viral quasispecies from which different isolates may emerge as selection pressures alter. Although the use of antiviral therapies has improved outcomes significantly for many chronically infected individuals, the emergence of drug-resistant and immune/vaccine-escape viruses ensures there is a continuing need for the development of new and imaginative approaches to control and eventually eradicate HBV.

Prevalence of hepatitis B virus precore stop codon mutations in chronically infected children

AIM: To find out whether there is a significant difference in the prevalence of the precore stop codon mutation between HBeAg positive and anti-HBe positive children.

METHODS: We investigated a large pediatric population of 155 European children (mean age 10.9 years) with chronic hepatitis B by PCR and direct sequencing. Ninety were HBeAg positive and 65 had seroconversion to anti-HBe. Additionally genotyping was performed.

RESULTS: Seventy-four (48%) of the sequenced HBV strains were attributed to genotype D and 81 (52%) to genotype A. In the group of 90 HBeAg positive patients, 2 (2.2%) 1896-G-to-A transitions leading to precore stop codon mutation were found, and in the group of 65 anti-HBe positive children, 5 (7.7%) were identified harbouring HBeAg-minus mutants. The difference was not statistically significant (P= 0 .13).

CONCLUSIONS: HBeAg minus variants as predominant viral HB strains play a minor role in the course of chronic hepatitis B in European children.

Clinical significance of hepatitis B virus (HBV) genotypes and precore and core promoter mutations affecting HBV e antigen expression in Taiwan

To assess the prevalence and clinical significance of hepatitis B virus (HBV) genotypes and precore and core promoter mutations in Taiwan, a cohort of 200 Taiwanese chronic hepatitis B patients was analyzed. The HBV genotypes and sequences of the precore and the core promoter regions were determined in 66 asymptomatic carriers and 134 patients who had liver biopsy-verified chronic hepatitis and liver cirrhosis. The HBV e-antigen (HBeAg)-negative patients had a higher frequency of mutations at core promoter nucleotides 1753 and 1773 and precore nucleotides 1846, 1896, and 1899 than HBeAg-positive patients. Among the 200 patients, the frequencies of genotype C, T1762 and A1764, C1753, T1766 and A1768, and A1896 mutations increased and the frequencies of T or G1752, T1773, G1799, and C1858 mutations decreased with advancing liver diseases. These factors were different between those with HBeAg-positive status and those with HBeAg-negative status. Based on multiple logistic regression analysis, the risk factors of liver cirrhosis for 200 patients were the presence of T1762 and A1764 mutations (odds ratio [OR] = 11.11; 95% confidence interval [CI] = 3.91 to 31.25; P < 0.001), age > or =35 years (OR = 3.42; 95% CI = 1.33 to 8.77; P = 0.011), and genotype C (OR = 2.87; 95% CI = 1.21 to 6.81; P = 0.017). Further categorical analysis found that 62.1% of patients with genotype C, T1762 and A1764 mutations and age > or =35 years had liver cirrhosis. None of the 55 patients infected with the genotype B, A1762 and G1764 wild type and age <35 years showed liver cirrhosis. In conclusion, our data suggest that pathogenic differences between HBeAg-positive and -negative patients may exist. In Taiwan, HBV genotype C and the T1762 and A1764 mutations may play a role in HBV-related liver cirrhosis, and these could serve as molecular markers for prediction of the clinical outcomes of chronic HBV patients.

Changes in viral loads of lamivudine-resistant mutants and evolution of HBV sequences during adefovir dipivoxil therapy

The addition of adefovir dipivoxil (ADV) to ongoing lamivudine therapy is effective against lamivudine-resistant virus in patients with hepatitis B virus (HBV) infection. We studied 39 patients who received ADV added to lamivudine for breakthrough hepatitis. We determined early viral changes (12 weeks) in YMDD mutants (rtM204I [YIDD sequence], rtM204V [YVDD]) and rtL180M in all 39 patients as well as amino acid changes in the polymerase reverse transcriptase (rt) region and precore/core promoter mutations in 15 patients who received long-term treatment (more than 1 year). Changes in rtM204I and rtL180M viral loads were greater than that of the rtM204V, albeit statistically insignificant. Moreover, the greatest change in viral load was seen for rtM204I without hepatitis B e antigen (HBeAg). The precore mutant was replaced with wild-type virus in three of eight patients after 1 year of added ADV therapy. Compared to baseline with lamivudine therapy only, new amino acid mutations were seen in the rt region at baseline with ADV in seven patients. At 1 year after ADV coadministration, the YMDD motif was replaced with wild-type (rt204M) in two patients, in whom mutations were fewer and of a different type. We conclude that the rtM204I may be more sensitive to ADV in vivo. ADV tended to select wild-type virus from precore mutants. Moreover, viruses that were wild-type in the rt region reappeared after 1 year of ADV coadministration in some patients.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Correlations of HBV genotypes, mutations affecting HBeAg expression and HBeAg/ anti-HBe status in HBV carriers

This study was carried out to determine the effects of hepatitis B virus genotypes, core promoter mutations (A1762G1764-->T1762A1764) as well as precore stop codon mutations (TGG-->TAG) on HBeAg expression and HBeAg/ anti-HBe status. Study was also performed on the effects of codon 15 variants (C1858/ T1858) on the predisposition of precore stop codon mutations (TGG-->TAG). A total of 77 sera samples were analyzed. Fifty one samples were successfully genotyped of which the predominant genotype was genotype B (29/ 51, 56.9 %), followed by genotype C (16/ 51, 31.4 %). Co-infections by genotypes B and C were observed in four samples (7.8 %). To a lesser degree, genotypes D and E (2.0 % each) were also observed. For core promoter mutations, the prevalence was 68.8 % (53/ 77) for A1762G1764 wild-type and 14.3 % (11/ 77) for T1762A1764 mutant while 9.1 % (7/ 77) was co-infected by both strains. The prevalence of codon 15 variants was found to be 42.9 % (33/ 77) for T1858 variant and 16.9 % (13/ 77) for C1858 variant. No TAG mutation was found. In our study, no associations were found between genotypes (B and C) and core promoter mutations as well as codon 15 variants. Also no correlation was observed between HBeAg/ anti-HBe status with genotypes (B and C) and core promoter mutations.