Hepatitis B virus genotype distribution among chronic hepatitis B virus carriers in Shanghai, China

A novel hepatitis B virus genotyping system by using restriction fragment length polymorphism patterns of S gene amplicons

AIM: Traditional hepatitis B virus (HBV) genotyping methods using restriction fragment length polymorphism (RFLP) can reliably identify genotypes A to F. As HBV genotypes G and H have been recently identified, this study was to establish an accurate and simple genotyping method for all eight HBV genotypes (A to H).

METHODS: Two hundred and forty HBV small S sequences obtained from GeneBank were analysed for restriction enzyme sites that would be genotype-specific. Restriction patterns following digestion with restriction enzymes BsrI, StyI, DpnI, HpaII, and EaeI, were determined to identify all eight HBV genotypes. Mixed genotype infections were confirmed by cloning and further RFLP analysis.

RESULTS: The new genotyping method could identify HBV genotypes A to H. Genotypes B and C could be determined by a single step digestion with BsrI and StyI in parallel. This was particularly useful in the Far East where genotypes B and C are predominant. Serum samples from 187 Chinese HBV carriers were analysed with this genotyping system, and the genotype distribution was 1.1% (2), 51.9% (97), 40.6% (76) and 4.8% (9) for genotypes A, B, C, and D, respectively. Mixed genotypes were found in only 3 patients (1.6%). Sequence data analysis confirmed the validity of this new method.

CONCLUSION: This HBV genotyping system can identify all eight HBV genotypes. It is accurate and simple, and can be widely used for studies on HBV genotyping.

Quantification and genotyping of hepatitis B virus in a single reaction by real-time PCR and melting curve analysis

BACKGROUND/AIMS

Both viral titer and genotype of hepatitis B virus (HBV) play critical roles in determining clinical outcome and response to antiviral treatment in hepatitis B patients. In this study, a method was developed to determine both parameters in a single-tube reaction.

METHODS

The method contains two consecutive steps, the first step used real-time PCR for quantification and second step used melting curve analysis for genotyping. For accurate quantification, the PCR primers and hybridization probes were selected from highly conserved regions to ensure the equivalent amplification and hybridization of all genotypes of HBVs. Within the sensor probe there exists signature single nucleotide polymorphisms (SNPs), which could effectively differentiate different HBV genotypes by showing different melting temperatures.

RESULTS

The quantification results showed great consistency with the commercial assays in linear range from 10(2) to 10(11) copies/ml. By comparison with the traditional restriction fragment length polymorphism (RFLP) methods, 99% of samples were accurately genotyped by current assay, and with a higher detection rate. In addition, this method can detect mixed HBV infections.

CONCLUSIONS

Currently, this methodology can be applied to areas prevalent with HBV genotypes B and C, providing an efficient alternative for clinical diagnosis and large-scaled longitudinal studies.

Simultaneous quantitation and genotyping of hepatitis B virus by real-time PCR and melting curve analysis

Hepatitis B virus (HBV) genotype and HBV DNA levels have been implicated in clinical evaluation and prognosis of patients with chronic HBV infection. The aim of the present study was to develop a rapid and sensitive method for simultaneous HBV DNA quantitation and differentiation between HBV genotypes B and C in a single-step reaction by real-time PCR and melting curve analysis using SYBR Green I fluorescent dye. The genotypes obtained by this method were compared with those examined by PCR-RFLP and direct sequencing on 52 serum samples of patients with chronic HBV infection. Using the results obtained by direct sequencing and phylogenetic analysis as the reference, the accuracy of HBV genotyping by PCR-RFLP and melting curve analysis was 90.38 and 92.31%, respectively. The geometric mean of HBV DNA levels was 3.42 x 10(6), 2.10 x 10(6), 1.19 x 10(5) and 3.10 x 10(4) copies/microl in asymptomatic carriers, patients with chronic hepatitis, cirrhosis and hepatocellular carcinoma, respectively. It is concluded that this method has the advantages of rapidity, reproducibility and accuracy, which would be feasible and attractive for large-scale analysis, particularly in regions where HBV genotypes B and C are prevalent.

Practical difficulties in the management of hepatitis B in the Asia-Pacific region

The Asia-Pacific Expert Committee on Hepatitis B Management recently reviewed the impact of hepatitis B in the region and assessed the differences and similarities observed in the practical management of the disease in individual Asia-Pacific countries. Hepatitis B is a major health concern in the Asia-Pacific region, and of all chronically infected carriers worldwide, approximately 75% are found in Asia. The disease poses a considerable burden on healthcare systems, and is likely to remain a cause of substantial morbidity and mortality for several decades. Disease prevention activities, including screening and vaccination programs, have been implemented successfully in some Asia-Pacific countries and similar measures are being established in other parts of the region. The management of hepatitis B in the Asia-Pacific varies throughout the region, with each country confronting different issues related to treatment options, disease monitoring and duration of therapy. The influence of cost, availability of diagnostic equipment, and patient awareness and compliance are of additional concern. Although guidelines such as those developed by the Asian Pacific Association for the Study of the Liver have been created to address problems encountered in the management of hepatitis B, many physicians in the region still find it difficult to make satisfactory management decisions because of the treatment choices available. This article examines the different approaches to hepatitis B management in a number of Asia-Pacific countries, and highlights the difficulties that can arise when adhering to treatment guidelines and disease prevention solutions that have proved to be successful in the region.

Eight genotypes (A-H) of hepatitis B virus infecting patients from San Francisco and their demographic, clinical, and virological characteristics

Clinical lines of evidence have been accumulated that hepatitis B virus (HBV) genotypes have characteristic geographical distributions and distinct clinical impact on liver diseases. The distribution of HBV genotypes was determined with reference to hepatitis B e antigen (HBeAg) and alanine aminotransferase (ALT) levels in 165 patients with hepatitis B in San Francisco. HBV genotypes were determined by enzyme-linked immunosorbent assay (ELISA) and the unclassified samples were sequenced within the S region for phylogenetic analysis. Genotype A occurred in 60 (36%) patients, B in 16 (10%), C in 56 (34%), D in 19 (12%), E in 1 (1%), F in 1 (1%), G in 8 (5%), and H in 4 (2%). Caucasians were infected predominantly with HBV genotype A (HBV/A) (38 of 57 [67%]), Asians with HBV/C (45 of 63 [71%]), and Hispanics with HBV/F and HBV/H (4 of 9 [44%]). Serum ALT levels were higher in the patients infected with HBV/A (P = 0.03) or HBV/G (P = 0.02) than HBV/C. HBeAg was more frequent in patients infected with HBV/G than HBV/C or HBV/D (7 of 8 [88%] vs. 25 of 56 [45%] or 6 of 19 [32%], P = 0.03 or 0.01). In conclusion, eight genotypes (A-H) were identified in San Francisco in association with various ethnicities and then influenced ALT levels as well as the prevalence of serum HBeAg. HBV genotype H might be identified by combination of preS2 serotpe bksf and HBsAg serotype adw.

Epidemiological study of hepatitis B virus genotypes, core promoter and precore mutations of chronic hepatitis B infection in Hong Kong

BACKGROUND/AIMS

We conducted a population study to document the prevalence of hepatitis B virus (HBV) genotypes in Hong Kong.

METHODS

HBV genotypes, core promoter (CP) and precore mutations were determined in 776 asymptomatic patients.

RESULTS

92.6% patients had single genotype [B (32.5%), C (62.5%)]. 99.1% of genotype B was subtype Ba. Patients with age <50 years had a lower prevalence of genotype B than patients with age >51 years (32.5% vs. 41%, respectively, P=0.028). Compared to patients with genotype C, patients with genotype B had a higher cumulative rate (P=0.018) and younger age (40.1 vs. 34.2 years, respectively, P=0.018) of HBeAg seroconversion. There were no differences in the HBV DNA levels between patients with genotypes B and C, and with wild-type and mutants of CP and precore regions. By multivariate analysis, patients with genotype C and with CP mutations had higher alanine aminotransferase (ALT) levels.

CONCLUSIONS

B and C were the two most common HBV genotypes in Hong Kong. The former had a higher chance of earlier HBeAg seroconversion and lower ALT levels. The prevalence of genotype B was lower in patients with age <50, probably related to influx of immigrants from China since 1949.

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.

Acute hepatitis B virus infection in Turkey: epidemiology and genotype distribution

The aim of this study was to investigate the prevalence of hepatitis B virus (HBV) genotypes in Turkey. Epidemiological and clinical data for 158 patients with acute HBV infection from 22 medical centres in the period February 2001 to February 2002 were collected prospectively. HBV genotyping was based on analysis of restriction fragment length polymorphisms and nested PCR. There were 59 female and 99 male patients, with a mean age of 34.2 +/- 15.6 years. The most common probable transmission route was blood contact in 63 (41.1%) cases, but was unknown in 78 (49.4%) cases. The mean alanine aminotransferase level was 1718 +/- 1089 IU/L. Four of the 158 patients (2.5%) died because of fulminant hepatitis. One year after discharge, 11 (10.6%) of 103 cases were positive for hepatitis B surface antigen (HBsAg) and 80 (77.7%) were positive for anti-HBsAg. Genotype determination was unsuccessful in 11 cases because of a negative PCR; genotype D was found in the remaining 147 cases. The results suggested that acute HBV infection constitutes a significant health problem in Turkey and that genotype D is predominant.

Epidemiology of HBV genotypes by nested PCR with multi-paired primers

AIM: To investigate the epidemiology of HBV genotypes among HBV-infected persons in northern China.

METHODS: The HBV DNA in 801 sera samples collected from hepatitis patients (594), healthy controls (154), and HCV-infected patients (53) were tested by nested PCR, the positive sera were then genotyped by nested PCR with six pairs of HBV genotype-specific primers (A to F).

RESULTS: 464 samples (57.9%) were HBV DNA positive among the 801 samples. Among 594 cases with various hepatitis B clinical manifestations, 74.4% (442/594) were HBV-DNA positive, while 8.4% (13/154) of healthy controls were HBV-DNA positive. There was significant difference between the hepatitis patients and healthy controls (P < 0.01). 17% (9/53) of HCV-infected patients were HBV-DNA positive, too. Among the 464 HBV-DNA positive samples, the persentage of genotype A was 5.2% (24/464), genotype B 7.1% (33/464), and type C 77.2% (358/464), type D 2.4% (11/464), while none of type E and F had been found in those samples. 14 samples (3%) were both type B and C positive. The 24 samples could not be genotyped in this study.

CONCLUSION: The HBV genotypes prevailed among HBV-infected persons in northern China are types A, B, C, and D, and the major genotype is type C (77.2%). Type C is also the major genotype among the clinical groups. There is no statistical difference between the groups.

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.

Hepatitis B virus X protein (HBx)-induced apoptosis in HuH-7 cells: influence of HBV genotype and basal core promoter mutations

BACKGROUND

Hepatitis B virus (HBV) infection is a serious, world-wide problem. HBV genotype and basal core promoter (BCP) mutations affect the clinical course of HBV-infected patients. BCP mutations also lead to mutations at HBV X protein (HBx) codons 130/131. The functional significance of naturally occurring variants of human HBx remains largely unknown. The purpose of the study was to investigate whether HBV genotypes or double mutations affect HBx-induced apoptosis.

METHODS

We constructed genotype A, B, C, and D HBx expression vectors and HBx expression vectors with double mutations at HBx codons 130K and 131V or positions 130M and 131I using site-directed mutagenesis. A transient expression system in HuH-7 cells was established and this model was utilized to address the effect of HBx on cell viability.

RESULTS

HBx-transfected cells showed a dose-dependent decrease in cell viability by MTS assay. A subset of cells expressing HBx underwent apoptosis according to terminal transferase enzyme-mediated end labeling of DNA and caspase-3 activity. This study demonstrated that HBx can induce cell death by apoptosis in a dose-dependent manner and that HBV genotypes and double mutations did not affect HBx-induced apoptosis.

CONCLUSIONS

HBV genotypes and mutation of two amino acids directly adjacent to the conserved Kunitz domain essential for transcription activating activity of HBx did not change the pro-apoptotic activity of HBx. Further study is needed to determine whether HBV genotypes and double mutations have any effect on the function of HBx.

Classifying hepatitis B virus genotypes

In 1988, hepatitis B virus (HBV) was classified into four genotypes by a sequence divergence in the entire genome exceeding 8%, and designated by capital letters of the alphabet from A to D. There are seven genotypes of HBV (A-G) at present, and an eighth is on the horizon. They have an uneven geographical distribution, and only a few of them are prevalent in a given area of the world. Thus genotype A is frequent in northwest Europe, Sub-Saharan Africa, India and the North, Central and South America, B as well as C are common in Southeast Asia and Oceania, and D is prevalent in the Mediterranean area, Central Asia and South America. Genotype E is restricted to West Africa, and F is localized in Central and South America. The distribution of genotype G added to the alphabet list very recently has yet to be determined. Coinfection with HBV of distinct genotypes is not infrequent and found in about 10% of infected individuals, and is responsible for intertypic recombination of HBV genomes. The mutation for a stop codon in the precore region (G1896A) for aborting the translation of hepatitis B e antigen (HBeAg) is prohibited in HBV genomes of genotype A, as well as some of genotypes C and F, because they possess C at position 1858 that makes a Watson-Crick pair with G at position 1896. Hence, seroconversion to antibody to HBeAg is forbidden or delayed in individuals who carry them. Evidence is accumulating as regards the influence of HBV genotypes on the progression of chronic hepatitis B and response to antiviral therapies. HBV isolates even of the same genotype can differ in virological and clinical characteristics, and therefore, the genotype needs to be classified further into subtypes, especially if they are clinically relevant.

Hepatitis B virus genotypes and hepatocellular carcinoma in Taiwan

With phylogenetic analysis of hepatitis B virus (HBV) isolates, eight different genotypes (A to H) have been recognized worldwide. The impact of HBV genotypes on the clinical aspects of HBV infection in Taiwan, including the clinical outcome of chronic infection and therapeutic response to antiviral treatments, has been clarified. Our data showed that genotypes B and C are the predominant HBV strains in Taiwan, and genotype C is associated with more severe liver disease including cirrhosis and hepatocellular carcinoma (HCC), whereas genotype B is associated with the development of HCC in young noncirrhotic patients. Serologically, genotype C tends to have a higher frequency of hepatitis B e antigen (HBeAg) positivity and a higher serum HBV DNA level than genotype B. In addition, genotype C patients, compared to genotype B patients, have a delayed HBeAg seroconversion in the immune clearance phase of chronic HBV infection. Virologically, genotype C bears a higher frequency of basal core promoter mutation than genotype B. Our recent data further indicated that patients with basal core promoter mutation are significantly more associated with the development of HCC than those without, which applies to both genotypes B and C. In addition, the prevalence of basal core promoter mutation in young HCC patients is comparable to older HCC patients but is significantly higher than that in age-matched inactive carriers, irrespective of genotypes. Although superinfection of HBV on hepatitis B carriers indeed occurs in Taiwan, it is rarely associated with acute exacerbations. As to the response to antiviral treatments, genotype C is associated with a lower response rate to interferon therapy compared to genotype B. In addition, genotype B seems to have a better virological response to lamivudine as compared to genotype C, but both genotypes have a similar risk in the development of lamivudine resistance. These lines of evidence highlight the remarkable differences in the clinical and virological characteristics between Taiwanese patients infected with different genotypes. In conclusion, pathogenic and therapeutic differences do exist among HBV genotypes in Taiwan, and determining the genotype in patients with chronic HBV infection would help gain further information in anthropologic, clinical, virological and prognostic investigations.

Hepatitis B virus genotypes and hepatocellular carcinoma in Japan

Hepatitis B virus (HBV) is one of the major causative agents of hepatocellular carcinoma (HCC) in Southeast Asia where HBV genotype B (HBV/B) and genotype C (HBV/C) are prevalent. Clinical and virological differences were evaluated between HCC patients in Japan and Taiwan, all of whom were infected with HBV/B and HBV/C. In Japan, the prevalence rates of HBV/B and HBV/C were 12 and 85%, respectively, in patients with chronic HBV infection, which is similar to those of 13 and 86% in patients with HCC. In the HCC patients with HBV/B, the mean age was 70 years and higher than that of 55 years in those with HBV/C. In Taiwan, however, HBV/B was detected in 61% and HBV/C in 31% of patients with HCC. Furthermore, the mean age of HCC patients with HBV/B in Taiwan was 50 years and younger compared to the 59 years of those with HBV/C. These differences may be explained by a distinct distribution of subtypes of HBV/B between the two countries. In Taiwan as well as in most Asian countries only the subtype Ba of HBV/B is found, while the majority of Japanese patients with HBV/B have the subtype Bj. Although the risk factors associated with HCC should be investigated with respect to host and environmental factors, the differences in genotypes and subtypes of HBV would need to be taken into consideration in etiological and clinical studies on HCC.

Genotypic distribution of hepatitis B virus in the Czech Republic: a possible association with modes of transmission and clinical outcome

OBJECTIVE

The relationship between hepatitis B virus (HBV) genotype with disease or treatment outcome is beginning to be characterized. However, the link between genotype and disease transmission route has not been closely examined. We addressed this question in high-risk populations in Prague, Czech Republic.

DESIGN

Patients with HBV infection were consecutively recruited into the study at an outpatient clinic between June 2000 and March 2001. Their serum samples were analysed for HBV S gene segments by polymerase chain reaction (PCR) test. The amplified product sequences were compared to those of known HBV genotypes. Patients were evaluated for other virus co-infections, and parenteral and sexual exposure histories.

RESULTS

Of 57 consecutively recruited patients with evidence of HBV infection, 45 (79%) had PCR-detectable S gene sequences. Only genotypes A (n = 33; 73%) and D (n = 12; 27%) were found. There was no difference in the development of chronic infection between the two genotypes. Of nine patients co-infected with TTV, all were infected with HBV genotype A. There was a trend towards an association between number of lifetime sex partners and genotype A but not genotype D.

CONCLUSIONS

In Prague, the number of HBV genotypes appears to be limited compared to other northern European countries, suggesting that the virus has recently spread in the high-risk populations. While a large proportion of HBV infections occur in intravenous drug users, a subset of HBV genotype A may be transmitted by sexual contact. An HBV subtype may influence modes of transmission of HBV.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Difference in prognosis between patients infected with hepatitis B virus with genotype B and those with genotype C in the Okinawa Islands: a prospective study

The factors contributing to the prognosis of hepatitis B virus (HBV)- related chronic liver disease were assessed prospectively in 72 patients with chronic hepatitis B confirmed clinically and pathologically. A comparative study was undertaken between patients infected with genotype B and those with genotype C. During the follow-up period, 13 (81.3%) of 16 patients with genotype B who were initially hepatitis B e antigen (HBeAg) positive became HBeAg negative and 14 (51.9%) of 27 with genotype C became HBeAg negative. HBeAg had been cleared in 8 (61.5%) of 13 patients with genotype B within the first 2 years of the follow-up, but in only one (7.1%) of 14 with genotype C (P < 0.05). Four (11.4%) of 35 patients with genotype B had progressed to cirrhosis, whereas, 12 (32.4%) of 37 patients with genotype C progressed to cirrhosis, including two patients with hepatocellular carcinoma. Multivariate analysis showed that difference in HBV genotype influenced significantly either the clearance of HBeAg or the development of cirrhosis. In conclusion, HBeAg was cleared from sera more frequently and earlier in patients with genotype B compared with those with genotype C, and development of cirrhosis occurred less frequently in patients with genotype B compared with those with genotype C. Thus, HBV genotypes may influence the prognosis of HBV-related chronic liver disease.

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Characterization of hepatitis B virus surface antigen and polymerase mutations in liver transplant recipients pre- and post-transplant

We evaluated serum samples from 18 chronic hepatitis B virus (HBV) patients who underwent liver transplantation for the presence of HBV polymerase and S gene mutations and HBV genotype using a new commercially available sequencing assay. All three patients with hepatitis B immune globulin (HBIG) treatment failure followed by nucleoside analogue treatment failure were infected with HBV genotype C; a pre-existing HBV S antigen (HBsAg) mutation (sD144A) was identified in one patient pretransplant, while sG145R mutations emerged in the other two patients post-transplant. These HBsAg mutations persisted for the duration of the study (5-6 years), despite the absence of HBIG administration for a 4-5-year period. Significant viral polymerase mutations (rtL180M and rtM204I/V) also emerged in all of these patients following treatment with lamivudine and/or famciclovir. Four of six patients with HBIG breakthrough without nucleoside analogue treatment failure yielded potentially significant HBsAg mutations post transplant. These data do not support previous reports highlighting the disappearance of HBsAg mutants in liver transplant recipients after discontinuation of HBIG. Determination of HBV genotype, as well as identification of HBV polymerase and S gene mutations in liver transplant candidates may be warranted to optimize HBV management strategies post transplant.

Molecular and serological aspects of HBsAg-negative hepatitis B virus infections in North America

A few hepatitis B virus (HBV) infections are characterized by the presence of HBV DNA in serum or liver tissue, or both, in the absence of detectable hepatitis B surface antigen (HBsAg) in serum. However, such infections have rarely been described previously in North American patients. In the present study, 31 hepatocellular carcinoma (HCC) patients from the United States and Canada who had no detectable HBsAg in their serum were studied. In these 31 HBsAg-negative HCC patients, HBV DNA was detected in HCC and/or in adjacent nontumorous liver tissue using nested polymerase chain reaction (PCR) in 5/9 (56%) patients from the United States and in 12/22 (55%) from Canada. The 17 HBV DNA-positive/HBsAg-negative patients from the United States and Canada included 9 without any serological markers for HBV and 8 with detectable antibodies to hepatitis B core antigen. In these patients, HBV genotype C was the most prevalent genotype (11/17; 64%). HBV genotypes have not been previously reported in HCC patients from North America. Replicative intermediate forms of HBV (covalently closed circular HBV DNA) were detected in 2/17 (12%) HBV DNA-positive/HBsAg-negative patients, indicating that at least two of these patients had actively replicating HBV infections. The use of tests to detect HBV DNA permitted the identification of HBV infections in HBsAg-negative HCC patients from North America. Among these patients, those with antibody to hepatitis C virus (HCV) would otherwise have been designated "HCV-associated HCCs" based on serological tests alone. These findings provide a new perspective on determining the possible viral etiologies of HCCs in North America.

Detection of HBV, PCNA and GST-π in hepatocellular carcinoma and chronic liver diseases

AIM: To investigate the change of HBV DNA, PCNA and GST-π in chronic liver disease and hepatocellular carcinoma (HCC).

METHODS: Hepatitis B surface antigen (HBsAg), proliferating cell nuclear antigen (PCNA) and glutathione S-transferases (GST-π) were detected by immunohistochemical staining and HBV DNA was detected by in situ hybridization (ISH) in formalin-fixed and paraffin-embedded sections with a total of 111 specimens of chronic hepatitis, liver cirrhosis, paratumorous tissue, HCC and normal liver tissue.

RESULTS: The positive rates of HBsAg and HBVDNA were 62.5%(15/24) and 75.0%(12/16) in chronic hepatitis, 64.0%(16/25) and 83.3%(15/18) in liver cirrhosis, 72.7% (16/22) and 85.7%(12/14) in the paratumorous tissu and 45.0%(14/31) and 64.3%(9/14) in HCC. The positive HBVDNA granules in chronic hepatitis, liver cirrhosis and the paratumorous tissue were more intense than that in HCC. The positive rates of PCNA and GST-π were 34.8%(8/23) and 25.0%(4/16) in chronic hepatitis, 73.7%(14/19) and 17.6%(3/17) in liver cirrhosis, 86.7%(13/15) and 53.3% (8/15) in the paratumorous tissue, 100%(15/15) and 60.0% (9/15) in HCC, respectively, and the positive rate of GST-π in the paratumorous tissue was significantly higher than that in the liver cirrhosis without tumor (P < 0.05), but same as that in HCC(P > 0.05).

CONCLUSION: The HBV infection may increase expression of PCNA and GST-π. The paratumor cirrhosis may be a sequential lesion of precancerous cirrhosis around HCC.

Influence of hepatitis B virus genotypes on the progression of chronic type B liver disease

To investigate the hepatitis B virus (HBV) genotype-related differences in the progression of liver disease, 585 patients with chronic HBV infection including 258 with histologically verified chronic liver disease (CLD) and 74 with hepatocellular carcinoma (HCC) were examined. The mean ages of both patients with advanced fibrosis (F3 or F4) and with HCC were significantly older in genotype B than in genotype C patients (P =.018, P =.024, respectively). Both the hepatitis B e antigen (HBeAg) negativity rate at biopsy and the cumulative HBe seroconversion rate in patients with CLD were significantly higher in genotype B patients than genotype C patients (P <.01, P =.022, respectively). Multivariate analysis revealed that genotype B, presence of precore mutation, high ALT levels, and severe histologic activity were independent factors for HBe seroconversion. Among all the biopsy-proven CLD patients, the ratio of patients with advanced fibrosis in genotype B was significantly lower than that in genotype C (4/30 vs. 74/224, respectively; P =.034). This difference was more remarkable in younger patients (< or =45 years; 1/25 vs. 47/180, respectively; P =.020), and there was no difference in older patients (>45 years). The distribution of each genotype between CLD and HCC was very similar (B and C: 11.2% and 87.0% vs. 10.8% and 89.2%, respectively). In conclusion, our results suggest that, although the patients with genotype B experience earlier HBe seroconversion, slower progression of liver fibrosis, and slower development of HCC, the life-long risk of progression to advanced fibrosis and development of HCC may not differ among genotypes B- and C-related chronic liver disease.

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.

HBV subtype as a marker of the clinical course of chronic HBV infection in Japanese patients

Hepatitis B virus (HBV) genotype C is predominant in Japan. However, many HBV subtypes are involved in each genotype, and the clinical manifestations in the patients associated with each subtype remain unknown. Therefore, we investigated the relationship between HBV subtype and clinical aspects of chronic HBV infection. The subtype of 237 patients with chronic HBV infection, including 74 asymptomatic carriers, was determined. The subtypes of 110 HBV carriers undergoing long-term follow-up management were determined twice to detect subtypic changes. The clinical features of the patients were also studied with regard to presence or absence of subtypic change. The subtypic distribution in the 237 HBV carriers was as follows: subtype adr, 161 (68%); subtype adw, 25 (11%); subtype adwr, 12 (5%); subtype ar, 24 (10%); subtype adyr, 4 (2%); and unclassified, 8 (3%). The proportion of asymptomatic carriers in patients with subtype adw was significantly higher than those in patients with subtype adr (56% vs. 28%, P < 0.05). In addition, the proportion of HCC in patients with subtype adwr was significantly higher than those in patients with subtype adr (25% vs. 6%, P < 0.05). The prevalence of subtype adr in 74 asymptomatic carriers tended to decrease with age (82% in carriers aged < or =35 years vs 43% in those aged > or =61 years, P < 0.05). The subtypic change and the course of chronic HBV infection had no significant correlation. These results suggest that HBV subtypes are associated with the clinical course of chronic HBV infection.

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.

Hepatitis D virus genotypes in intravenous drug users in taiwan: decreasing prevalence and lack of correlation with hepatitis B virus genotypes

Of 368 hepatitis B virus (HBV)-infected intravenous drug users, 144 (39%) were positive for antibody to hepatitis D virus (anti-HDV). Anti-HDV-positive HBV carriers had a lower rate of positivity for HBV DNA than did anti-HDV-negative carriers (52 versus 73%, respectively). From 1986 to 1997, the average rate of decrease in the prevalence of HDV infection in this population was 4.7%/year.

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.

Preponderance of hepatitis B virus genotype B contributes to a better prognosis of chronic HBV infection in Okinawa, Japan

The present study was designed to examine the distribution of hepatitis B virus (HBV) genotypes among patients at various stages of chronic liver disease type B in Okinawa Prefecture, Japan, where the prevalence of hepatitis B surface antigen is the highest in Japan despite the lowest mortality rate from primary liver cancer. Serum samples from 227 HBV carriers were determined for HBV genotype by polymerase chain reaction (PCR)-restriction fragment length polymorphism. Five of 227 sera were negative for HBV DNA by nested PCR and were excluded from the genotype analysis. Genotype B was predominant in asymptomatic carriers (45/67, 67%), whereas genotype C was predominant in chronic liver disease: 49% (50/103) in patients with chronic hepatitis, 63% (20/32) in patients with cirrhosis, and 60% (12/20) in patients with hepatocellular carcinoma. The distribution of genotype B decreased with increasing liver disease severity. However, this tendency was seen among patients aged less than 50 years old, whereas the prevalence of genotype B was similar among carriers with various liver diseases who were older than age 50. In conclusion, HBV genotype B was prevalent and less frequent among patients with advanced liver disease, particularly in patients aged less than 50 years. These findings suggest that the preponderance of genotype B is responsible for the low mortality rate of primary liver cancer associated with HBV seen in Okinawa Prefecture, despite having the highest HBV carrier rate in Japanese.

Global control of hepatitis B virus infection

Worldwide about 350 million people are chronic carriers of the hepatitis B virus (HBV). The infection can cause acute and chronic liver disease including cirrhosis and hepatocellular carcinoma (HCC). Hepatocellular injuries of HBV infection are predominantly immune-mediated, and the natural history of chronic infection can be divided into three phases based on virus-host interactions-namely, immune tolerance, immune clearance, and viral integration phases. Four serotypes (adw, ayw, adr, and ayr) and seven genotypes (A to G) of HBV have been identified, and they show some distinct geographic distributions. The HBV genotypes may have clinical relevance and are currently under investigation. On the basis of disease burden and the availability of safe and effective vaccines, the WHO recommended that by the end of the 20th century hepatitis B vaccine be incorporated into routine infant and childhood immunisation programmes for all countries. The efficacy of universal immunisation has been shown in different countries, with striking reductions of the prevalence of HBV carriage in children. Most important, hepatitis B vaccination can protect children against HCC and fulminant hepatitis, as has been shown in Taiwan. Nevertheless, the implementation of worldwide vaccination against HBV requires greater effort to overcome the social and economic hurdles. Safe and effective antiviral treatments are available but are still far from ideal, a situation that, hopefully, will be improved soon. With hepatitis B immunisation, the global control of HBV infection is possible by the end of the first half of 21st century.

Hepatitis B virus genotype B is associated with earlier HBeAg seroconversion compared with hepatitis B virus genotype C

BACKGROUND & AIMS

Recent studies suggest that hepatitis B virus (HBV) genotype B is associated with less active liver disease than HBV genotype C. The aim of our study was to determine if HBV genotype B is associated with higher rates of spontaneous hepatitis B e antigen (HBeAg) seroconversion compared with genotype C.

METHODS

A retrospective study using stored sera from 332 Chinese patients with chronic HBV infection followed for a mean of 48 months (range, 12-98) were tested for HBV genotype using a line-probe assay.

RESULTS

HBV DNA was detected in 273 patients, 122 had HBV genotype B and 147 genotype C. Patients with genotype B had a significantly lower prevalence of HBeAg at presentation and significantly higher rates of spontaneous HBeAg seroconversion during follow-up. HBV genotype B patients who were HBeAg positive were significantly younger, and spontaneous HBeAg seroconversion occurred approximately 1 decade earlier compared with HBV genotype C patients. Multivariate analyses identified high alanine aminotransferase (baseline and follow-up), age >30 years, and genotype B as independent factors associated with spontaneous HBeAg seroconversion.

CONCLUSIONS

HBV genotype B is associated with earlier HBeAg seroconversion than genotype C. This finding may explain the less active/progressive liver disease in patients with genotype B.

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.

Hepatitis B viral genotypes: clinical relevance and molecular characteristics

Hepatitis B virus (HBV) infection is a global health problem and the clinical outcome of chronic HBV infection depends on the frequency and severity of hepatitis flares in the immune clearance phase. Currently, four subtypes and seven genotypes of HBV are identified and most have specific geographic distributions. The impact of HBV genotypes on the clinical outcome of chronic HBV infection has been partially clarified. In Taiwan, genotype C is associated with more severe liver disease and genotype B is associated with the development of hepatocellular carcinoma (HCC) in young non-cirrhotic patients. In contrast, genotype B has a relatively good prognosis in Japan and China and is rarely associated with the development of HCC. Similarly, genotype D is associated with more severe liver disease than genotype A in India and may predict occurrence of HCC in young patients. Although superinfection of HBV on top of hepatitis B carriers occurs in Taiwan, it is rarely associated with acute exacerbations. As to the response to antiviral treatment, genotypes C and D are associated with a lower response rate to interferon therapy compared with genotypes B and A. In addition, the subtype adw is reported to be associated with a higher risk of lamivudine resistance than ayw. In HBV subtype adw-infected HCC patients, genotype B responds better to embolization therapy and has a lower rate of HCC recurrence than genotype C. In summary, pathogenic and therapeutic differences do exist among HBV genotypes and determining the genotype in patients with chronic HBV infection would help gain further information for etiologic, clinical, virologic and anthropologic investigations. Further studies to clarify the molecular virological factors that contribute to these differences are awaited.

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.

Profile, spectrum and significance of HBV genotypes in chronic liver disease patients in the Indian subcontinent

BACKGROUND AND AIM

Certain hepatitis B virus (HBV) genotypes have been alleged to be associated with the development of cirrhosis and hepatocellular carcinoma (HCC), and the response to interferon therapy in Taiwanese patients. We undertook to study the prevalence and significance of HBV genotypes in the Indian subcontinent.

METHODS

One hundred and thirty histopathologically proven chronic HBV-infected patients, including 52 incidentally detected asymptomatic hepatitis B surface antigen (HBsAg)-positive subjects (IDAHS) with chronic HBV infection (group I), 48 cirrhotics (group II) and 30 hepatocellular carcinoma (HCC; group III) patients were studied. Hepatitis B virus genotypes were determined by using restriction fragment length polymorphism, and direct sequencing of the s gene including the 'a' determinant region.

RESULTS

Only genotypes A (46%) and D (48%) were found in the chronic HBV-infected patients. A mixed infection with genotypes A and D was seen in 6% of patients. Genotype A was found in 42, 48 and 50%, and genotype D in 48, 50 and 47% of group I, II and III patients, respectively (P = NS). The patients who had mixed genotypes were significantly younger (P < 0.05). In group I (IDAHS) patients infected with genotype D, none had a histological activity index (HAI) of < four. Genotype D was significantly more common in group I patients with HAI > 4 as compared to genotype A (53 vs 32%, P < 0.05). Similarly, genotype D was associated with more severe liver diseases (61 vs 30%, P < 0.05). Genotype D was more prevalent in HCC patients of < 40 years of age, as compared to IDAHS (63 vs 44%, P = 0.06).

CONCLUSIONS

(i) Hepatitis B virus genotypes A and D are prevalent in chronic liver disease patients of Indian origin; and (ii) HBV genotype D is associated with more severe diseases and may predict the occurrence of HCC in young patients.