Hepatitis B virus genotype A rarely circulates as an HBe-minus mutant: possible contribution of a single nucleotide in the precore region

Influence of hepatitis B virus genotypes on the response to antiviral therapies

Hepatitis B virus (HBV) has been classified into eight genotypes (A-H) based on genome sequence divergence. Genotypes of HBV have distinct geographical distributions, and two genotypes account for most HBV worldwide. Hepatitis B e antigen expression lasts longer and liver disease is more severe with graver outcomes in carriers of genotype C than B in Asia. Accumulating lines of evidence indicate a better response to interferon and lamivudine in patients with chronic hepatitis B who are infected with genotype B rather than C. The therapeutic response may differ, however, in patients infected with HBV of the same genotype. For example, the response to lamivudine is poorer in patients infected with subtype Ba, which contains a recombination with genotype C, than in those with subtype Bj without such a recombination. Influence of genotypes on therapeutic response needs to be examined in patients infected with the other genotypes, particularly in those with genotype A or D infection.

Occult hepatitis B virus infection in chronic liver disease: full-length genome and analysis of mutant surface promoter

BACKGROUND AND AIMS

Genome sequence of hepatitis B virus (HBV) from occult chronic infection is scarce. Fifty-six (9.4%) of 591 patients seronegative for hepatitis B surface antigen (HBsAg) with chronic liver disease were positive for HBV DNA. The complete HBV genome from 9 of these patients (S1-S9) and 5 controls positive for HBsAg (SWT.1-SWT.5) were analyzed.

METHODS

Overlapping genome fragment amplification, cloning, and sequencing was performed on these cases. Functional analysis of surface promoter was conducted using fusion construct.

RESULTS

All patients with occult infection except one (S8) had a low viral titer. Eight patients had infection with genotype A (S1-S5, SWT.1-2, SWT.5) and 6 had infection with genotype D (S6-S9, SWT.3-4). S4 and S5.1 of genotype A had the characteristic nucleotide deletions in core and pre-S1 region seen in genotype D. The major observations in patients with occult HBV infection were as follows: frequent quasispecies variation, deletions in pre-S2/S region affecting the surface promoters (nt 3025-54) and pre-S protein (S3, S5, S6, S8), truncated precore (S6, S8, S7.1) and core (S9) owing to stop signal, alternate start codon for the Polymerase gene (S3, S9), and YMDD mutation (S1, S4, S9) in patients not on antiviral therapy. HBsAg and core proteins could be shown immunohistochemically in 3 of 5 liver biopsy specimens available. The mutant surface promoters (pre-S2 and S) on functional analysis showed alterations in HBsAg expression.

CONCLUSIONS

These changes in the regulatory region with possible alterations in the ratio of large and small surface proteins along with other mutations in the genome may decrease the circulating HBsAg level synergistically, making the immunodetection in serum negative.

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.

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.

Hepatitis B virus genotypes and precore and core mutants in Brazilian patients

A method for genotyping hepatitis B virus by partial HBsAg gene sequencing with primers common to all known genotypes was developed. Mutations related to anti-HBs resistance are also detected with this method. Samples from 103 Brazilian patients were analyzed. Precore and core region of these viruses were also sequenced in 101 patients. Genotypes A, B, C, D, and F were found with frequencies of 49.5, 2.9, 13.6, 24.3, and 9.7%, respectively. Genotypes B and C were found only in Asian patients, whereas genotypes A, D, and F were more common in patients without an Asian background. Precore mutants were found in 32 (31.7%) of 101 patients, with a higher frequency in those infected with genotype D (22 of 25 [88.0%]). Analysis of nucleotide 1858 showed presence of thymine in all patients with genotypes B, C, and D and in a few patients with genotypes A (10.0%) and F (30.0%), who showed more frequently the presence of cytosine. This nucleotide was closely related to the presence of precore mutants. Mutations in the basal core promoter were found in 64 of 101 (63.4%) samples. These mutations were more frequent in patients infected with genotype F (90.0%) and less frequent in patients infected with genotype B (33.3%). Deletions in this region were found in two genotype C-infected patients.

Epidemiological and sequence differences between two subtypes (Ae and Aa) of hepatitis B virus genotype A

Complete nucleotide sequences of 19 hepatitis B virus (HBV) isolates of genotype A (HBV/A) were determined and analysed along with those of 20 previously reported HBV/A isolates. Of the 19 HBV/A isolates, six including three from Japan and three from the USA clustered with the 14 HBV/A isolates from Western countries. The remaining 13 isolates including four from The Philippines, two from India, three from Nepal and four from Bangladesh clustered with the six HBV/A isolates reported from The Philippines, South Africa and Malawi. Due to distinct epidemiological distributions, genotype A in the 20 HBV isolates was classified into subtype Ae (e for Europe), and that in the other 19 into subtype Aa (a for Asia and Africa) provisionally. The 19 HBV/Aa isolates had a sequence variation significantly greater than that of the 20 HBV/Ae isolates (2.5+/-0.3 % vs 1.1+/-0.6 %, P<0.0001); they differed by 5.0+/-0.4 % (4.1-6.4 %). The double mutation (T1762/A1764) in the core promoter was significantly more frequent in HBV/Aa isolates than in HBV/Ae isolates (11/19 or 58 % vs 5/20 or 25 %, P<0.01). In the pregenome encapsidation (epsilon) signal, a point mutation from G to A or T at nt 1862 was detected in 16 of the 19 (84 %) HBV/Aa isolates but not in any of the 20 HBV/Ae isolates, which may affect virus replication and translation of hepatitis B e antigen. Subtypes Aa and Ae of genotype A deserve evaluation for any clinical differences between them, with a special reference to hepatocellular carcinoma prevalent in Africa.

Double point mutation in the core promoter region of hepatitis B virus (HBV) genotype C may be related to liver deterioration in patients with chronic HBV infection

BACKGROUND AND AIM

Hepatitis B virus (HBV) genotype C has a more severe pathogenesis than genotype B in Japan. We retrospectively investigated the relationship between HBV genotype and the core promoter (CP) (nt 1762 and 1764) and precore (PreC) (nt 1896) mutations of the HBV genome.

METHODS

A total of 129 Japanese patients (42 genotype B and 87 genotype C) with chronic HBV infection, living in two different geographical areas in Japan, were evaluated (mean follow-up period 10.1 +/- 3.8 years). In 2000, CP and PreC HBV mutations were analyzed by direct sequencing from sera. Hepatitis B e antigen (HBeAg), HBV DNA and serial alanine aminotransferase (ALT) changes were followed and determined using serological methods.

RESULTS

Genotype C patients had significantly higher rates of HBeAg (40.2%vs 2.4%), HBV DNA positivity (75.9%vs 7.1%) and ALT abnormality (71.3%vs 11.9%) than genotype B patients (all P < 0.05). Among genotype B patients, CP wild type (92.9%) was predominant and PreC mutation (88.1%) was predominant. However, among genotype C patients, CP mutation (75.9%) was predominant and PreC mutation (66.7%) was predominant. The CP mutation was found significantly more in genotype C than in genotype B (P < 0.05). Of the 67 patients with ALT abnormality, five (7.5%) genotype B and 62 (92.5%) genotype C patients (31 HBeAg positive and 31 negative) were found. Among the 31 genotype C patients who were HBeAg positive, the combination of CP mutation and PreC wild (54.8%) was predominant, while among the remaining 31 genotype C patients who were HBeAg negative, the combination of CP mutation and PreC mutant (71.0%) was predominant.

CONCLUSION

Genotype C might be one of the worse prognostic markers in patients with chronic HBV infection, possibly because of mutation in the CP region.

Uncommon mutation pattern of a hepatitis B virus isolate from genotype F infecting a patient with AIDS

OBJECTIVE

To study the genomic variations of a hepatitis B virus (HBV) isolate in a patient coinfected with human immunodeficiency virus type 1 (HIV-1) who developed severe hepatitis and died of AIDS.

METHODS

Two blood samples were collected, the first one during the asymptomatic phase of HIV-1 infection, and the other, 3 years later, few months before the death of the patient. Both samples were HBsAg and anti-HBe positive. Pre-S/S and precore-core genome regions were PCR amplified and analyzed.

RESULTS

The HBV isolate belonged to genotype F, cluster IV. A number of unique amino acid substitutions were found in the surface antigen gene and the overlapping polymerase coding region of HBV genomes derived from both samples. However, these substitutions reflected natural variations rather than mutations of clinical significance. The precore stop codon mutation A(1896) was present in both genomes. Furthermore, the HBV genome derived from the second, but not first sample, showed two out-of-frame core interval deletions, one and 103 nucleotides in length, respectively.

CONCLUSIONS

This is the first report of an HBV isolate from genotype F with core internal deletions. Our results suggest an association between specific core mutations and the severe hepatitis developed by the patient.

Wild-type precore and core promoter sequences in patients with acute self-limited or chronic hepatitis B

BACKGROUND

Mutations in the precore region and core promoter were compared between patients with acute and chronic hepatitis B.

METHODS

There were 69 patients with acute self-limited hepatitis B and 210 with chronic hepatitis B who had been followed for > 15 years. The hepatitis B virus (HBV) of genotypes A, B and C was detected in 14 (23%), 8 (13%) and 28 (45%) of the patients with acute self-limited hepatitis, respectively, in contrast to 11 (5%), 25 (12%) and 167 (80%) of those with chronic hepatitis.

RESULTS

At presentation, hepatitis B e antigen (HBeAg) in serum was the more common (82% versus 65%, P < 0.05), and the wild-type sequences of the precore region (100% versus 74%, P < 0.001) and core promoter (88% versus 36%, P < 0.00001) were more frequent in the 50 patients with acute self-limited hepatitis than the 203 patients with chronic hepatitis B who were infected with HBV of genotype A, B or C. Wild-types of both the precore region and core promoter persisted in acute self-limited hepatitis, while they decreased from 28% to 10% in chronic hepatitis over the course of > 15 years.

CONCLUSION

HBV with the wild-type sequences of the precore region and core promoter prevails in patients with acute self-limited hepatitis, unlike in patients with chronic hepatitis.

Distribution of hepatitis B viral genotypes and mutations in the core promoter and precore regions in acute forms of liver disease in patients from Chiba, Japan

BACKGROUND

Although it has been reported that different hepatitis B virus (HBV) genotypes induce different clinical characteristics in patients with chronic liver diseases (CLD), there have been few reports that have detailed the distribution of HBV genotypes in acute forms of liver disease.

METHODS

HBV genotypes were determined in 61 patients who had acute forms of liver disease (45 had acute self limited hepatitis (AH) and 16 had fulminant hepatitis (FH)) and in 531 patients with CLD, including 19 patients with severe acute exacerbation of CLD. We also analysed the enhancer II, core promoter, and precore region sequences for the presence of mutations.

RESULTS

Expression of genotype B in patients with acute forms of liver disease was significantly greater than in those with CLD (39.3% v 11.7%, respectively; p<0.001). Furthermore, expression of genotype B was significantly greater in patients with FH than in those with AH (62.5% v 31.1%, respectively; p=0.027). The precore mutation A1896 and the core promoter mutation at nt 1753 and 1754 were found more frequently in FH than in AH, and genotype B was predominant in FH regardless of the presence of these mutations.

CONCLUSIONS

HBV genotype B was found more frequently in patients with acute forms of liver disease than in patients with CLD, and more frequently in patients with FH than in those with AH. These results suggest that this HBV genotype may induce more severe liver damage than other viral genotypes, at least in patients from Chiba, Japan.

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.

The T(1858) variant predisposing to the precore stop mutation correlates with one of two major genotype F hepatitis B virus clades

The precore mutation G(1896)-->A occurs frequently in anti-HBe-positive carriers of HBsAg with T(1858) in the stem of the encapsidation signal. Hepatitis B virus (HBV) genotype F, considered an Amerindian genotype, subdivides into two clades and the precore mutation occurs in Central American F strains. To investigate the relationship between substitutions at position 1858 and these clades, the precore and small S genes of 48 strains of HBV genotype F were subjected to phylogenetic analyses. Isolates of one clade, formed mainly of Central American strains, all had T(1858) and Thr(45) in the S gene, whereas in the other clade, formed mainly of South American strains and one strain from Polynesia, all had C(1858) and Leu(45). The latter strain was related to strains from Venezuela and Colombia, supporting an Amerindian contribution to the Polynesian population. The position of the Polynesian strain in the phylogenetic tree indicates that the two clades have resulted from an early split, showing a high degree of genetic stability of the stem of the HBsAg encapsidation signal.

Hepatitis B virus genotypes and virologic response in 694 patients in phase III studies of adefovir dipivoxil1

BACKGROUND & AIMS

Hepatitis B virus (HBV) genotype may influence disease progression and antiviral response. We therefore analyzed the frequency and distribution of genotypes in patients from 2 multinational phase III studies of adefovir dipivoxil. Antiviral efficacy of adefovir dipivoxil 10-mg therapy was examined with respect to HBV genotype, hepatitis B e antigen (HBeAg) serostatus, and race.

METHODS

HBV genotypes were assigned by phylogenetic analyses of DNA sequences amplified from baseline serum samples (n = 694).

RESULTS

Patients from Asia/Oceania were infected predominantly with genotypes B and C, whereas patients from Western European countries were infected predominantly with genotypes A and D. In Mediterranean countries, genotype D was dominant. The most common genotype in North America was C, followed by A, B, and D. Regardless of location, Asian patients were infected predominantly with genotypes B or C, whereas Caucasian patients were infected predominantly with A or D. There were significant differences in the baseline serum HBV-DNA levels of patients infected with different HBV genotypes regardless of HBeAg serostatus. Forty-eight weeks of adefovir dipivoxil 10-mg therapy resulted in potent reductions in serum HBV DNA with no significant differences based on genotype, HBeAg status, or race; similarly, there was no statistical difference in HBeAg seroconversion rates between genotypes in these patients.

CONCLUSIONS

HBV genotypes were distributed asymmetrically with respect to race, geography, and HBeAg status. Forty-eight weeks of adefovir dipivoxil therapy resulted in significant decreases in serum HBV-DNA levels in patients regardless of HBV genotype, HBeAg status, or race.

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.

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.

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.

Viral genotypes and response to interferon in patients with acute prolonged hepatitis B virus infection of adulthood in Japan

Acute hepatitis B virus (HBV) infection was diagnosed in 57 adults admitted to Toranomon Hospital in Tokyo, Japan. Genotypes of HBV were determined by a serological method and compared to those in 1,077 patients with chronic hepatitis B. The distribution of genotypes were: genotype A (acute, 22.8% vs. chronic, 1.9%; P < 0.00001); B (14.0% vs. 9.4%); C (43.9% vs. 87.7%, P = 0.004); D (1.8% vs. 0.2%); F (1.8% vs. 0.2%); and unable to be typed (15.8% vs. 0.6%, P = 0.001). The infection persisted in seven (12%) of them. They included six (86%) of the seven patients who received prednisolone or glycyrrhizin during an acute phase of illness and one of the 41 (2%) who did not (P = 0.01). Interferon was given to the seven patients with acute prolonged HBV infection, and four of them responded by clearing hepatitis B e antigen (HBeAg) and surface antigen (HBsAg) from serum. Of the four responders, one was infected with HBV genotype B and three with genotype C. HBsAg persisted in the remaining three patients all of whom were infected with HBV genotype A, and HBeAg stayed positive in one of them. These results indicate that HBV genotype A prevails in Japanese patients with acute hepatitis B, and suggest a high efficacy of interferon in the adult patients with acute prolonged HBV infection, except in those infected with HBV genotype A.

Clinical relevance of viral dynamics and genotypes in hepatitis B virus

Advances in molecular diagnostic technology make it possible to accurately measure viral loads and this has allowed the detailed study of viral dynamics of HIV, hepatitis C virus (HCV) and hepatitis B virus (HBV). Following antiviral therapy, there are at least two phases of viral load decay: one corresponding to clearance of free virions and a second, slower phase corresponding to eradication of infected cells. Application of mathematical models allows for the assessment of antiviral efficacy and improved design of therapeutic regimens. The clinical application of these tools should help optimize patient outcome. Another advantage of molecular diagnostics is characterization of the heterogeneity of viruses in particular patient populations under selective pressure situations. The HBV can be classified into seven major genotypes (A-G) that have mainly a geographic distribution. Recent genotypic studies have revealed the clinical and therapeutic relevance of viral genotyping in HBV infections.

Influence of hepatitis B virus genotype on the long-term outcome of chronic hepatitis B in western patients

BACKGROUND & AIMS

The aim of this study was to investigate if the variable outcome of chronic hepatitis B may be related to hepatitis B virus (HBV) genotype.

METHODS

The clinical and virologic events observed over prolonged follow-up in 258 Spanish patients with chronic hepatitis B infected with different genotypes of HBV were compared.

RESULTS

The prevalence of genotype A, D, and F was 52%, 35%, and 7%, respectively. Concomitant sustained biochemical remission and clearance of HBV DNA occurred at a higher rate in genotype A- than in genotype D- (log-rank, 14.2; P = 0.002) or genotype F-infected patients (log-rank, 4.2; P = 0.03). The rate of hepatitis B surface antigen (HBsAg) clearance was higher in genotype A than in genotype D hepatitis (log-rank, 4.6; P = 0.03). Sustained remission and clearance of HBsAg were associated with infection with genotype A by Cox regression analysis. Seroconversion to antibody to hepatitis B e antigen (anti-HBe) was unrelated to HBV genotype, but the rate of sustained remission after seroconversion was higher in genotype A than in genotype D hepatitis both in patients who seroconverted to anti-HBe during follow-up (log-rank, 4.5; P = 0.03) and in patients with positive anti-HBe at baseline (log-rank, 6.66; P = 0.009). Death related to liver disease was more frequent in genotype F than in genotype A (P = 0.02) or genotype D (P = 0.002) hepatitis.

CONCLUSIONS

The long-term outcome of chronic hepatitis B is different in patients infected with HBV genotype A, D, or F.

Histologic activity of childhood chronic hepatitis B related to viremia levels, genotypes, mutations, and epidemiologic factors

BACKGROUND

Despite high viral load, children with chronic hepatitis B virus (HBV) infection may lack significant biochemical signs of liver dysfunction. Failure to develop abnormal liver chemistriesis is probably due to immunologic hyporeactivity. Despite the absence of biochemical abnormalities in these patients, there is still a risk for long-term complications. The pathogenic importance of viral load and genetic variability is less well studied in children than in adults.

METHODS

We evaluated viremia levels, genotypes, and mutations related to histologic evidence of liver damage in 71 HBV carriers, aged 2 to 18 years, all of non-Swedish origin.

RESULTS

None of the of 22 children who were hepatitis B e antigen (HBeAg) negative had severe liver disease or had HBV DNA levels greater than 10 copies/mL (mean 10 ); 3 (14%) of them had increased alanine aminotransferase (ALT). The 49 HBeAg-positive children had a mean HBV DNA level of 10 copies/mL, and increased ALT was seen in 28 (55%). Core promoter mutations (at nt 1764) or precore mutations (at codon 1, 2, or 28) were rare; they were seen in four and one HBeAg-positive children, and in four and nine HBeAg-negative children, respectively, without association to liver damage. C-1858 was associated with more liver inflammation. Genotype did not significantly influence liver damage. Children with horizontal transmission had a faster rate of seroconversion and more inflammation of the liver.

CONCLUSIONS

Severe HBeAg-negative hepatitis with high HBV DNA levels and mutations in the core promoter or precore regions seems to be less common in children than in adults. C-1858 strains may be more pathogenic, but this requires further study. Epidemiologic factors influence the course of infection.

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.

Core promoter mutations (A(1762)T and G(1764)A) and viral genotype in chronic hepatitis B and hepatocellular carcinoma in Guangxi, China

Hepatitis B viruses (HBV) with core promoter mutations (A(1762)T, G(1764)A) were found in a previous study to be highly prevalent in patients from Guangxi, China with hepatocellular carcinoma (HCC). The aim of this study was to determine whether the mutations are prevalent in areas of Guangxi with high and lower incidences of HCC and whether they are associated with other severe sequelae of chronic hepatitis B, including the development of cirrhosis. In addition, the genotypes of the various HBV sequences were determined. Core promoter mutations were significantly more common in HCC patients than asymptomatic carriers from both regions of Guangxi and also were common in patients with cirrhosis and chronic hepatitis. The data also support the hypothesis that genotype C HBV causes more severe liver disease than does genotype B.

Detection and significance of a G1862T variant of hepatitis B virus in Chinese patients with fulminant hepatitis

The prevalence of a G1862T variant of hepatitis B virus (HBV) has been investigated in patients with fulminant hepatitis and chronic liver disease, using primer mismatch amplification, followed by restriction fragment length polymorphism analysis. This variant was five times more common in patients with fulminant hepatitis (13.7%, 7 of 52) than in chronic carriers (2.5%, 2 of 81). The G-->T substitution at position 1862 leads to an amino acid change in codon 17 of the precore protein of the virus, which is part of a signal peptidase recognition motif. Variants with this mutation were only seen in patients infected with genotype B. In vitro translation experiments showed that this variant has greatly reduced capacity to produce hepatitis B e antigen (HBeAg) from its precore protein precursor. Furthermore, 88.5% of patients with fulminant hepatitis had mutations that are known to be associated with abrogated or reduced production of HBeAg. This suggests that, following HBV infection, the absence or reduced amounts of HBeAg may be a contributing factor in fulminant disease.

Hepatitis B virus genotypes in Uzbekistan and validity of two different systems for genotyping

Hepatitis B virus (HBV) has been classified into seven genotypes, designated A-G. The HBV genotype has a characteristic geographical distribution. The Republic of Uzbekistan is located in the heart of Asia and has been considered to be a region with high endemicity of hepatitis viruses. However, the present distribution of hepatitis virus infection in this region is unknown. The aim of this study was to investigate the distribution of HBV genotypes and to elucidate the validity of two genotyping systems in Uzbekistan. Fifty-four patients with hepatitis B surface antigen were investigated. HBV genotypes were determined by two methods: one based on restriction fragment length polymorphism (RFLP) targeting to S region, and another on enzyme-linked immunosorbent assay (ELISA), using monoclonal antibodies to pre-S2 region. Seven (13%) and 47 (87%) of the 54 subjects were classified into genotypes A and D, respectively. Dual infection of two viral populations of the same genotype was observed in one subject. No significant difference of ALT level (203.3 +/- 244.7 vs. 190.6 +/- 39.5) and HBeAg (42.9% vs. 42.6%) were found between genotypes A and D. In this study, the validity of the genotyping systems in this region was confirmed.

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

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

'Hbe minus' mutants of hepatitis B virus. Molecular characterization and its relation to viral genotypes

The precore-core and S genes of HBV were directly sequenced from serum samples of 42 patients with chronic hepatitis B (16 hepatitis Be antigen [HBeAg]+and 26 anti-HBe+). Viral genotype A was identified in 12 cases, genotype D in 11 and genotype F in 19 cases. Precore mutations, mainly M1 (G1896A, stop at codon 28) were similarly found among viral genotypes A and D: seven cases (58%) and six cases (55%), respectively. The selection of M1 mutants from genotype D resulted in a more stable encapsidation signal but was less stable for genotype A precore mutants. Oddly enough, the encapsidation signal of M1 precore mutants from genotype F sequences were evenly distributed among less stable (genotype A M1 mutants) and more stable encapsidation signal (genotype D M1 mutants). This study shows that the selection of precore mutants that preclude the HBeAg expression, including the M1 mutation, does not necessarily depend on the stabilization of the encapsidation signal or the viral genotype In addition, the particular behavior of genotype F genomes at precore region is described.

Hepatitis B virus genotypes and clinical manifestation among hepatitis B carriers in Thailand

BACKGROUND

Hepatitis B virus (HBV) genotypes have distinct geographic distributions. The aim of the present study was to evaluate the distribution of HBV genotypes and their clinical relevance in Thailand.

METHODS

Hepatitis B virus genotypes among 107 hepatitis B carriers residing in Thailand were evaluated using serologic and genetic methods. They were clinically classified into asymptomatic carriers with normal serum alanine transaminase (ALT) levels and patients with chronic liver disease, such as those with chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular carcinoma (HCC).

RESULTS

Hepatitis B virus genotype distribution among the 107 patients was 25.2% for genotype B, 72.0% for genotype C and 2.8% for genotype D. The serum ALT levels, HBV-DNA and hepatitis B e antigen positivity were significantly higher in carriers infected with genotype C HBV than in those infected with genotype B (P < 0.05). The proportion of genotype B HBV was higher in asymptomatic carriers than in patients with CH and those who developed liver disease, such as LC and HCC (45.5, 16.9 and 25.0%, respectively; P < 0.05). In contrast, the proportion of genotype C HBV was higher in patients who developed liver disease and CH than in asymptomatic carriers (68.7, 83.0 and 50.0%, respectively; P < 0.05). Phylogenetic analysis based on entire genome sequences revealed three HBV isolates, which were classified into a subgroup of genotype C in isolates from South-East Asian countries.

CONCLUSIONS

Genotypes B and C are the predominant types among hepatitis B carriers residing in Thailand and those genotypes influence the clinical manifestation in carriers with chronic hepatitis B infection.

Genetic variability in hepatitis B viruses

In 1988, it was reported that the full nucleotide sequences of 18 hepatitis B virus (HBV) strains clustered into four genetic groups (A to D) with more than 8% divergence between the groups. This classification of strains in terms of genome sequence has since proven to be an important tool in the understanding of HBV epidemiology and evolution and has been expanded to include three more genotypes. In parallel with the HBV genotypes described in humans, HBV strains isolated from different primates and hepadnaviruses found in woodchucks, ground squirrels, ducks and herons have been studied. Sequence differences between HBV genotypes can lead to structural differences at the level of the pregenome and can also lead to dramatic differences at the translational level when specific and commonly occurring mutations occur. There is increasing evidence that the clinical picture, the response to treatment and the long-term prognosis may differ depending on which genotype has infected the patient. The consideration of traditional serological patterns in a patient must therefore take the genotype of the infecting strain into account. Nucleotide variability between HBV strains has been used in several studies to trace routes of transmission and, since it is becoming increasingly clear that the differences between HBV genotypes are important, the need for reliable and easy methods of differentiating HBV genotypes has arisen. This review summarizes the knowledge of HBV genotypes with regard to their genetic, structural and clinically significant differences and their origin and evolution in the context of the hepadnaviruses in general.

Pretransplantation pre-S2 and S protein heterogeneity predisposes to hepatitis B virus recurrence after liver transplantation

Liver transplantation (LT) in patients with hepatitis B virus (HBV) infection often is complicated by recurrence of infection despite immunoglobulin treatment. To evaluate whether variability in HBV genomic sequences and the target of antibody to hepatitis B surface antigen action in pre-LT samples may be associated with a high recurrence rate, HBV pre-S/S regions of 14 HBV-positive candidates for LT (in 9 of these patients, HBV infection subsequently recurred) were amplified and sequenced. Two hundred ninety-one mutations in 1,167 sequenced nucleotides (24.9%) were found. Of these, 120 mutations (10.2%) led to an amino-acid change. The only significant difference between patients with and without recurrent disease was in the number of mutations in the pre-S2 region (total mutations, P =.042; missense mutations, P =.012) of pre-LT HBV DNA. In addition, a difference in amino-acid level was present in the pre-S2 region (P =.030). The delay in HBV infection recurrence was proportional to the number of pre-LT HBV mutations in the pre-S2 and S genes: the higher the number, the longer the interval between LT and recurrence of infection (pre-S2, P =.0124; S, P =.0060; total number of mutations in S protein, P =.0421). In conclusion, pre-LT determination of pre-S/S gene sequence variability showed that heterogeneity of the pre-S2 and, to a lesser extent, S genes was associated with a greater chance for HBV recurrence. Modification of B-cell epitopes of S, but especially of pre-S2, protein leading to conformational changes and alterations in the viral encapsidation and secretion process may facilitate HBV recurrence and contribute to the failure of immune globulin therapy.

Viral genotype and hepatitis B virus DNA levels are correlated with histological liver damage in HBeAg-negative chronic hepatitis B virus infection

OBJECTIVES

We aimed to study the relationship between the hepatitis B virus (HBV) genotypes, core promoter/precore stop codon mutations, and histological liver damage among hepatitis B e antigen (HBeAg)-negative patients.

METHODS

Liver biopsy specimens of 55 HBeAg-negative chronic HBV-infected patients were studied. A histological activity index was scored for degree of necroinflammation (HAI-NI) and fibrosis (HAI-F) as described by Knodell et al. HBV DNA was determined by a cross-linking assay and polymerase chain reaction (PCR) at the core promoter/precore region and the S region. PCR-positive samples were directly sequenced for core promoter and precore mutations and examined by restriction fragment length polymorphism for genotyping.

RESULTS

Forty-one males and 14 females at a median age of 43 were studied. HBV DNA was detectable in 32 (58%) and 37 (67%) patients by the cross-linking assay and PCR, respectively, at the time of liver biopsy. The median (range) HAI-NI and HAI-F scores were 5 (1-10) and 2 (0-4), respectively. HBV DNA detectable by either the cross-linking assay or PCR was associated with a higher HAI-NI score. Eleven and 31 patients had genotypes B and C HBV, respectively. Genotype C HBV was associated with higher HAI-NI than genotype B HBV. Core promoter mutations and precore stop codon mutation were detected in 74% and 40% patients, respectively, but they were not associated with higher HAI-NI or HAI-F scores.

CONCLUSIONS

Detectable HBV DNA and genotype C HBV, but not core promoter or precore stop codon mutations, are associated with more severe liver damage in HBeAg-negative patients.

World-wide epidemiology of HBeAg-negative chronic hepatitis B and associated precore and core promoter variants

Hepatitis B is a serious disease that is endemic in many parts of the world. A significant proportion of patients with chronic hepatitis B (CHB) are infected with a variant form of the hepatitis B virus (HBV) which decreases or abolishes the production of hepatitis B e-antigen (HBeAg). The purpose of this literature review is to describe the epidemiology of HBeAg-negative CHB (e-CHB) worldwide. A literature search was conducted to identify studies pertaining to e-CHB and underlying variants (precore and core promoter). Fifty studies were included in our analysis. The median prevalence of e-CHB among patients with chronic HBV infection was 33% in the Mediterranean, 15% in Asia Pacific, and 14% in the USA and Northern Europe. The pre core stop codon variant was detected in a median of 60% (range 0-100%) of HBeAg-negative patients overall, 92% in the Mediterranean, 50% in Asia Pacific and 24% in the USA and Northern Europe. There were very few data on the prevalence of core promoter variants outside Asia where the median prevalence among HBeAg-negative patients was 77%. This literature review revealed that e-CHB is more common than previously suspected and that it is present worldwide with marked variations in the prevalence of associated HBV variants across different geographical regions. Additional research using population based samples of adequate size based on a consensus definition of e-CHB and using standardized HBV DNA assays is needed to better estimate the true prevalence of e-CHB and its associated HBV variants.

Laboratory diagnosis of viral hepatitis in China: the present and the future

Viral hepatitis is one of the most prevalent infectious diseases in China. To date, all five types, hepatitis A, B, C, D and E have been reported in China, and the incidences of all these types are high in the Chinese population. Serological tests are mainly used for the diagnosis of hepatitis A, B, C and E in patients, epidemiological surveys and for efficacy studies of vaccines. Currently, nucleic acid-based assays are only used in research and for evaluation of antiviral and immuno-therapies.

Hepatitis B virus harboring nucleotide deletions in the core promoter region and genotype B correlate with low viral replication activity in anti-HBe positive carriers

BACKGROUND

Emergence of anti-HBe following seroconversion of HBe antigen indicates reduced hepatitis B virus (HBV) replication in the liver and low infectivity in the natural course of infection. However, some patients show continued replication or reactivation even in the presence of anti-HBe.

OBJECTIVE

To clarify the cause of HBV replication, we investigated genotype differences and mutations in the core promoter and precore region in relation to virus titer.

STUDY DESIGN

Using quantification of HBV DNA, nucleotide sequencing of the core promoter and precore region, and genotyping with the S gene by restriction fragment length polymorphism (RFLP), we analyzed sera of 26 anti-HBe positive carriers (28 serum samples).

RESULTS

Various mutations were detected including C to T point mutation at nt 1653, A to T and G to A contiguous point mutations at nt 1762 and 1764 in the core promoter region, and G to A point mutation at nt 1896 in the precore region, but no common mutations were detected that were directly related to the virus titer from earlier reported mutations. In contrast, the mean titer of genotype B virus was 1.5 x 10(5) copies per ml and that of mutant HBV of genotype C having 8 base pairs (8-bp) deletion (nt 1768-1775) in the core promoter region was 7.9 x 10(4) copies per ml (mean titer). These titers showed commonly lower than that of genotype C virus without 8-bp deletion (median titer 5.0 x 10(6) copies per ml). Transition of genotype from C to B after viral reactivation and reduction of proportion of 8-bp deletion mutant at reactivation period was observed in a patient who demonstrated exacerbation of liver dysfunction due to immunosuppressive therapy and increased viral replication.

CONCLUSIONS

These results confirm those of our earlier study describing low replication ability of 8-bp deletion mutant HBV in vitro, and also indicate that the presence of genotype B correlates with reduced titer of HBV.

Structural and functional heterogeneity of naturally occurring hepatitis B virus variants

Most organisms have developed sophisticated machineries to preserve their genomic integrity. On the contrary hepatitis B virus (HBV), like a lot of other viruses can undergo rapid and drastic sequence changes, especially if the virus has to cope with natural or therapy induced antiviral mechanisms in the host. Here, we try to summarize possible implications for the molecular pathogenesis of HBV based on the extensive research on the genetic variants of HBV.

Genotype may correlate with liver carcinogenesis and tumor characteristics in cirrhotic patients infected with hepatitis B virus subtype adw

To identify the influence of hepatitis B virus (HBV) genotype on development of hepatocellular carcinoma (HCC) and clinical outcome in chronic HBV infection, 26 consecutive cirrhotic patients infected with HBV subtype adw were investigated prospectively. HBV serology was undertaken using subtype-specific antibodies against hepatitis B surface antigens. The HBV genotype was determined by sequencing directly the polymerase chain reaction products of the HBV S gene. When HCC occurred, patients underwent transcatheter arterial embolization therapy. If tumor necrosis was incomplete, additional embolization therapy was carried out after a 3- to 4-month interval. At a median follow-up of 14.1 years (range 2.2 to 31.7), HCC occurred in 9 (35%) of 26 patients. Nineteen patients were infected with genotype B and 7 with genotype C. Four of the 19 genotype B patients (21%) and 5 of the 7 genotype C patients (71%) developed HCC (P = 0.058). Patient age (<45 years or 45 < or = ) at diagnosis of cirrhosis was the only significant independent factor influencing liver carcinogenesis by multiple logistic regression analysis and Cox's regression analysis (P = 0.0069 and 0.029, respectively). When analysis was limited to the age of 45 years or more at the last visit, genotype was the only contributory factor to HCC development by univariate analysis (P = 0.038). Whereas genotype B patients responded well to embolization therapy and had no recurrence of HCC for a prolonged period of time, genotype C patients showed poor responses and died of hepatic failure due to rapid HCC progression despite embolization therapy. The cumulative incidence of survival was significantly higher in the genotype B group (P = 0.0049). The HBV genotype correlated with the development of HCC, response to embolization therapy, and recurrence of HCC. Determination of HBV genotype may be useful in predicting outcomes in HBV subtype adw-related cirrhosis.

Diagnosis and management of pre-core mutant chronic hepatitis B

Chronic hepatitis due to pre-core hepatitis B virus (HBV) mutants presents as hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). HBeAg-negative CHB represents a late phase in the natural course of chronic HBV infection that develops after HBeAg loss and seroconversion to anti-HBe. It is usually associated with pre-core stop codon mutation at nucleotide 1896 (mainly selected in non-A HBV genotypes), but also with other pre-core changes or with mutations in the basic core promoter region (mainly in HBV genotype A). In chronic HBV infections, pre-core mutants can be detected both in patients with HBeAg-negative CHB and in inactive hepatitis B surface antigen (HBsAg) carriers. The diagnosis of HBeAg-negative CHB is based on HBsAg positivity, HBeAg negativity, and mainly on increased alanine aminotransferase (ALT) and serum HBV-DNA levels and exclusion of other causes of liver disease. The differential diagnosis between patients with CHB and inactive HBsAg carriers can be made only by close follow-up of aminotransferase activity and viraemia levels, although the cut-off level of serum HBV DNA has not been definitely determined. IgM anti-HBc levels have also been suggested as an index that increases the diagnostic accuracy for transient hepatitis flares, while liver biopsy confirms the diagnosis and evaluates the severity of the liver disease. Interferon-alpha (IFN-alpha) and lamivudine are the two drugs that have been tried, mainly in the management of HBeAg-negative CHB. A 12-month course of IFN-alpha achieves sustained biochemical remission in about 20% of patients, which has been associated with improvement in the long-term outcome of this subset. A 12-month course of lamivudine is rather ineffective, maintaining remission in less than 15% of patients after cessation of therapy. Long-term lamivudine is associated with progressively increasing rate of virological and subsequent biochemical breakthroughs due to YMDD mutants, with approximately 30% of patients remaining in remission in the third year of therapy. Several other antiviral agents are currently being evaluated in this setting with combined regimens being the most reasonable step for the near future.

Phylogenetic origin of hepatitis B virus strains with precore C-1858 variant

Mutations that prevent the expression of the hepatitis B e antigen frequently emerge in the immunoreactive phase of infection. The predominant mutation, the precore G-->A-1896 mutation, is restricted by the variability at position 1858 and is rare in strains with cytosine at nucleotide 1858. The C-1858 variant is characteristic of genotype A. It also occurs in genotypes C and F, but not in B, D, or E, explaining the geographical variation in the prevalence of precore mutants. C-1858 strains have been frequently observed in southeast Asia, but have not been phylogenetically characterized. By sequencing eight complete hepatitis B virus genomes, C-1858 variants of east Asian origin were found to constitute a phylogenetic entity within genotype C that probably diverged several hundred years ago. Further study of the distribution of this variant is warranted.

Clinical relevance of precore and basal core promoter variants of hepatitis B virus during natural hepatitis B e antigen seroconversion may be overstated

BACKGROUND

Clinical relevance of nucleotide changes in precore and basal core promoters in the hepatitis B virus genome during hepatitis B e antigen seroconversion may be overstated. The authors investigated the existence and changes in the relative proportion of variants to wild virus that occur with seroconversion.

METHODS

Sera from 30 school-aged long-term hepatitis B virus carriers, including 11 tested before and after seroconversion during 1 to 8 years of follow-up, were evaluated for variations in nucleotide sequences of the basal core promoter (T1762 and A1764), precore region (A1869), and carboxyl-terminus of the X region of the hepatitis B virus genome using an amplification refractory mutation detection system with mutant-specific primers.

RESULTS

All variants were found to already exist before seroconversion at various wild-type/mutant ratios. The positive rates of these variants were not changed with loss of hepatitis B e antigen. Although there was a relative increase in the concentration of these mutants in wild-type/mutant mixed populations, most patients with only a wild-type population maintained the same pattern after loss of hepatitis B e antigen.

CONCLUSIONS

Our results indicate that hepatitis B virus exists as a quasi species, and correlations of nucleotide sequences with clinical and serologic findings must be done with caution.

Low frequency of mutations in the core promoter and precore regions of hepatitis B virus in anti-HBe positive Brazilian carriers

BACKGROUND

Mutations in the core promoter and precore regions of the hepatitis B virus (HBV) genome, notably the double substitution (AGG to TGA) at nt positions 1762-1764 in the core promoter, and the precore stop codon mutation G to A at nt 1896, can often explain the anti-HBe phenotype in chronic carriers. However, the A1896 mutation is restricted to HBV isolates that have T at nt 1858. The double substitution at positions 1762-1764 has been described to occur preferentially in patients infected with strains showing C instead of T at nt 1858.

RESULTS

HBV DNAs from 29 anti-HBe Brazilian samples were characterized by nucleotide sequencing of PCR products from precore region. Among them, 18 isolates presented C at nt 1858 (mostly genotype A strains). The 11 remaining isolates (genotypes D and F) had T1858. The stop codon mutation at nt 1896 was found in seven isolates (24% of the total and 63% of the isolates that had T1858). The frequency of the double substitution at positions 1762-1764 was surprisingly low (20%) among C1858 isolates. An association between A1896 and TGA 1762-1764 mutations was observed among genotype D isolates: these showed either none of the two mutations or both. Furthermore, strains mutated at positions 1896 and/or 1762-1764 also presented an elevated number of other, less common substitutions in the core promoter and precore regions.

CONCLUSIONS

The data reported here are not in accordance with some reports from other parts of the world. In half of the isolates, none of the mutations previously described could explain the anti-HBe phenotype.

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

BACKGROUND AND AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nucleotide divergences in the core promoter and precore region of genotype D hepatitis B virus in patients with persistently elevated or normal ALT levels

BACKGROUND

Mutation in the hepatitis B virus precore codon 28, creating a translational stop codon and double 1762-1764 T/A mutations in the core promoter region, controlling the transcription of the precore RNA and the core RNA have been suggested to correlate with the HBeAg status of patients with HBV infection.

OBJECTIVES

The aim of the study was to further investigate the association of nucleotide divergences in both core promoter and precore regions with liver cell injury (reflected by ALT levels) in patients with chronic HBV infection.

STUDY DESIGN

The sequences of the core promoter and the precore region of HBV isolated from 67 patients, all having genotype D and subtype ayw were analyzed. The patients were divided into two groups and four subgroups according to their HBeAg and Anti-HBe status, and ALT profile.

RESULTS

It was found that the nucleotide divergences in the core promoter but not in the precore region were higher in patients having persistently elevated serum ALT than in serum ALT normal patients in both HBeAg positive and Anti-HBe positive groups (P<0.05). The number of T/A and A1896 stop codon mutations did not yield a statistically significant difference between ALT normal and elevated groups. It was also found that 1762-1764 T/A and precore A 1896 mutation existed in five and six out of 29 HBeAg positive patients, respectively. In 38 anti-HBe positive patients, 1762-1764 T/A and precore A1896 mutation were detected in three and 16 patients respectively, and coexisted in 10 patients.

CONCLUSIONS

Precore A 1896 stop codon mutation seems to play an essential role in the loss of HBeAg in Turkish patients. Serum viremia levels of HBV in patients having precore stop codon and/or T/A mutation were not significantly different from the other patients carrying wild type strains. Nucleotide variability in the core promoter region may be one of the factors linked to hepatitis B disease activity.

Homologous recombination between different genotypes of hepatitis B virus

Phylogenetic analysis was used to examine the evolutionary relationships among 99 complete HBV sequences. Analysis revealed nine viral genomes clustered with different genotypes depending on genome region analyzed. This discordance indicated that recombination events occurred during HBV history. The putative breakpoints between genomes of different genotypes have been mapped. Six mosaic genomes representing B/C hybrids were isolated in East Asia and three A/D hybrids in Italy. At least some recombinant strains appear to be fully viable and possess high evolutionary potential. As a result, B/C recombinants overspread through the East Asia region. They were found among the isolates from Japan, China and Indonesia. Our results suggest that recombination is a significant and relatively frequent event in the evolution of HBV genome. A possible mechanism and the implications of recombination for the natural history of HBV, clinically important properties, and phylogenetic reconstruction are discussed.

Rapid detection of genotypes and mutations in the pre-core promoter and the pre-core region of hepatitis B virus genome: correlation with viral persistence and disease severity

BACKGROUND/AIMS

We aimed to clarify the clinical relevance of hepatitis B virus pre-core mutant detection in patients with chronic hepatitis B using a newly developed assay.

METHODS

Viral genotypes and pre-core mutations were studied in relation to viral persistence and liver disease severity using INNO-LiPA methodology. The study group included 151 patients with chronic hepatitis B, 85 positive for HBeAg (group I) and 66 positive for anti-HBe (group II).

RESULTS

The prevalence of viral genotypes in group I was: 64% A, 1% B, 15% C, 19% D, 0% E, 0% F and in group II: 39% A, 0% B, 2% C, 56% D, 2% E, 2% F (p<0.001). The prevalence of mutations at pre-core codon 28 (M2) was lower in group I (5%) than in group II (64%) (p<0.001). The prevalence of pre-core promoter mutations was also lower in group I (21%) than in group II (61%) (p<0.001). M2 mutations were more frequently detected in genotype D than in genotype A (p<0.001), while the other mutations were not influenced by viral genotype. Serum HBV DNA levels were significantly lower in group II versus group I (p<0.001), and in patients with any of the pre-core mutations versus wild-type sequence (p<0.01). Although cirrhosis was more frequent in group II (37%) versus group I (22%) and in patients with either one of the pre-core mutation (31%) versus wild-type sequence (25%), there was no statistical difference in liver severity assessed by ALT levels and Knodell score.

CONCLUSION

Pre-core mutants, whose molecular pattern is strongly dependent on viral genotypes, are associated with viral persistence in anti-HBe positive patients with ongoing chronic hepatitis B. The availability of this rapid assay should allow a precise monitoring of viral pre-core mutants during the course of chronic hepatitis B.

An aberrant genotype revealed in recombinant hepatitis B virus strains from Vietnam

Six genotypes of hepatitis B virus (HBV) have been described. However, relatively few complete genomes originating from East Asia, where most of the world's HBV carriers live, have been studied. We analysed five complete HBV genomes of Vietnamese origin, which in our previous studies had produced atypical genotyping patterns. All five strains had HBsAg sequences with markers for serotype adw. In phylogenetic tree analysis, two of the genomes clustered with genotype C, and three clustered on a separate branch between genotypes A, B and C, suggesting a new genotype. However, these three strains showed signs of recombination in similarity plot and bootscanning analysis. Phylogenetic tree analysis of two segments separately supported recombination between genotype C and a putative new genotype (or possibly a subgroup of genotype A). The segment between nt 1801 and 2865 was clearly of genotype C origin, while the major part of the genome (nt 2866-1800) was placed on a branch close to genotype A. The findings encourage further study of genotypes and recombination in HBV from this geographical region.