Hepatitis B virus genotypes in chronic liver disease patients from New Delhi, India

A Recent Prevalence of Hepatitis B Virus (HBV) Genotypes and Subtypes in Asia: A Systematic Review and Meta-Analysis

Background and Aim: Despite introducing the hepatitis B virus (HBV) vaccine, the incidence of the Hepatitis B virus globally is still a major health concern. This systematic review and meta-analysis were conducted to provide detailed information on the prevalence of HBV genotypes and subtypes in circulation in Asia. Methods: A systematic search for articles describing the prevalence of HBV genotypes and subtypes in Asia was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Results: Our search returned 207 eligible articles involving 49,279 genotypes and 7457 subtypes representing 28 Asian countries. A meta-analysis was performed on our eligible studies using the Random effect Model. The pooled prevalence of HBV genotypes showed that genotype C (30.9%) (95% CI, 27.5–34.5%; I2 = 97.57%; p < 0.001) was the most common HBV genotype in Asia, followed by genotype B (17.8%) (95% CI, 15.5–20.4%; I2 = 97.26%; p < 0.001) and genotype D (15.4%) (95% CI, 11.8–19.8%). Vietnam had the highest prevalence of genotype B, Lebanon had the highest prevalence of genotypes C, and Jordan had the highest prevalence of genotype D. There was variation in genotypic prevalence with respect to the target genes for HBV genotyping. Reverse dot blot hybridization had the highest estimate of genotypes B and C. HBV subtype C2 (40.0%) (95% CI, 33.3–47.0) is the most prevalent HBV subtype. Conclusion: Evidence from this study reveals that HBV genotypes C and B are the most dominant HBV genotypes in Asia, and HBV subtype C2 is more endemic in Asia.

Epidemiology, Genotyping, Mutational and Phylogenetic Analysis of Hepatitis B Virus Infection in North-east India

BACKGROUND/OBJECTIVE

Hepatitis B virus (HBV) infection is a major public health problem globally. Northeast India is home to indigenous tribes with different ethnicity and high rates of drug abuse and HIV infection. The study was designed to estimate the burden of HBV infection across various spectrums of liver diseases from this region. HBV genotypes and subgenotypes play a role in the chronicity of disease, response to treatment and its progression. As very limited data are available from this region, we tried to elucidate the role of HBV genotypes, HBV mutants and their phylogenetic analysis.

METHOD

We designed a prospective multicentric study, and included 7464 liver disease cases, 7432 blood donors and 650 health care workers, who were screened for HBV infection. HBV DNA positive patients were genotyped and subjected to surface protein, precore and core mutation and phylogenetic analysis.

RESULTS

The prevalence of HBV infection with respect to different types of liver diseases, blood donors and health care workers was 9.9% (1550/15,546). 49.5% (768/1550) cases were found to be HBV DNA positive. The most common genotype was found to be genotype D 74.2% (570/768), followed by genotype C 6.5% (50/768), A 4.4% (34/768) and I 0.9% (7/768).

CONCLUSION

This study highlights the high hepatitis B burden in Northeast India, reflecting lacunae in health care needs of the region. Also, the different genotype distribution and presence of mutations may translate into different rates of liver disease progression, prognosis and ultimately, clinical significance. However, further prospective cohort study from Northeast India is warranted, to elucidate the clinical significance of multiple genotypes and mutation in this unique population.

Molecular epidemiology of HBV among HIV infected individuals in Chennai, south India

Hepatitis B is a major co-infection among people with HIV (PWHIV) worldwide. There is a paucity of data on HBV genetic diversity in India, which would be useful for targeted preventive and management interventions. To characterize the distribution of HBV genotypes and sub-genotypes, samples of 180 HIV-HBV co-infected individuals from a study previously conducted to estimate the prevalence of HBV co-infection were analyzed. Nested PCR using type-specific primers was used to identify the various HBV genotypes. Partial HBV S sequences were generated for a subset of samples using Sanger sequencing. Mutation analysis was done using the online HBVseq program. PCR based genotyping documented D (69.4 %) and A (5.6 %) to be the major genotypes in the study population. Infection with multiple genotypes was observed in 25 % co-infected individuals. D2, D5, A2, and A1 were the sub-genotypes detected. Mutations 184K and 173L were identified. HBV genotypes/ sub-genotypes play a pivotal role in the clinical outcome of chronic hepatitis B (CHB). Therefore, monitoring of CHB cases is needed to track disease progression, including early detection of hepatocellular carcinoma.

Molecular characterization of hepatitis B virus reveals circulation of multiple subgenotypes of genotype D with clinically important mutations in central India

PURPOSE

Hepatitis B virus (HBV) is one of the leading causes of morbidity and mortality across the globe. The pathogenesis, clinical outcomes, disease progression and response to antiviral treatment of HBV depend on infecting genotypes and mutations across HBV genome. There is a lack of such information from central India. The present study was planned to identify genotype/subgenotype and epidemiologically important mutation in HBV circulating in the area.

METHODS

Samples positive for HBsAg by ELISA from 2012 to 2016 were included and analysed in this retrospective study. The amplification of partial S gene (n = 25) and full genome (n = 10) was carried out to determine the genotype/subgenotype and genome wide mutations of HBV. The sequencing data was analysed using bioinformatics tools.

RESULTS

All 25 sequences belonged to genotype D; subgenotypes D1, D2, D3 and D5 with dominance of D1 were detected in the study subjects. Mutational profiling revealed the presence of nucleotide substitutions in promoter/regulatory/precore region associated with liver disease progressions. The amino acid (aa) changes associated with vaccine escape, immune escape, antiviral resistance and progression to liver cirrhosis (LC) or hepatocellular carcinoma (HCC) were detected.

CONCLUSIONS

This maiden molecular study on HBV from central India indicates that the genotype D with subgenotypes D1, D2, D3 and D5 harbouring mutations of clinical and epidemiological importance are in circulation. This study will serve as a baseline for future. Studies with larger sample size may aid in identifying the circulation of more genotypes.

Distribution of hepatitis B virus genotypes in the general population of Myanmar via nationwide study

Background

Hepatitis B virus (HBV) infections are a severe health concern worldwide. HBV is a DNA virus with a rapid rate of mutation. Based on heterogeneity of the nucleotide sequence, the HBV strains are divided into nine genotypes, each with a characteristic geographical distribution. Identifying and tracking alterations of HBV genotypes is important in epidemiological and transmission studies, and contributes to predicting the risk for development of severe liver disease and response to antiviral treatment. The present study was undertaken to detect HBV genotypes and sub-genotypes in the general population of different states and regions in Myanmar.

Methods

In 2015, a total of 5547 adults of the general population, residing in seven states, seven regions and the Nay Pyi Taw Union Territory, were screened for Hepatitis B Surface antigen (HBsAg) by the immunochromatographic test (ICT). Of the 353 HBsAg positive samples, the HBVDNA was identified using polymerase chain reactions (PCR) targeting the DNA sequences encoding the Pre-S region. A total of 153 PCR positive samples were subsequently subjected to genotyping by partial genome sequencing in both directions. The resulting sequences were then edited, aligned, and compared with reference sequences using the National Centre for Biotechnology Information (NCBI) web-based genotyping tool.

Results

Three HBV genotypes (HBV genotype B, genotype C and genotype D) were detected in Myanmar, of which genotype HBV genotype C (66.7%) was the most prevalent, followed by HBV genotype D (32%) and HBV genotype B (1.3%). Sub-genotyping revealed a total of 7 variants within the B, C and D genotypes: 2 (B4 and B5) in HBV genotype B, 3 (C1, C5 and C7) in HBV genotype C, and 2 (D3 and D6) in HBV genotype D.

Conclusion

HBV genotype C, sub-genotype C1 was predominantly distributed in all states and regions of Myanmar. This study is the first report on the nationwide distribution of HBV genotypes and sub-genotypes in Myanmar. We believe our findings will enable huge support for the hepatitis disease surveillance program, since HBV infection is one of the National Priority Diseases in Myanmar.

Prevalence of Hepatitis B Virus, Genotypes, and Mutants in HBsAg-Positive Patients in Meerut, India

Background

Genetic changeability of hepatitis B virus (HBV) signifies a challenge for the sensitivity of immunologic and molecular diagnostics. Therefore, knowing the spread of HBV genotypes (GENs) and mutation has considerable impacts on treatment strategies, vaccination program, diagnosis, and prevention. The present study aimed to detect HBV GENs and mutants in HBsAg-positive patients.

Methods

The study conducted on 4927 patients in Meerut, India, between March 2013 and April 2017. The blood specimens were analyzed for HBsAg using an ELISA kit, then the blood samples from HBsAg-positive patients were subjected to HBeAg assay and DNA isolation. Amplification of the HBV DNA of pre-S gene and pre-core or basal core promoter region were performed by RT-PCR and sequenced to analyze both GEN and mutation.

Results

According to the results, 245 cases were positive for HBsAg, and 55 were HBeAg-positive. With regard to HBV DNA levels, 16 samples were found positive in PCR assay with 7 (43.8%) less than 2000 IU/mL, 4 (25%) between >2000 and 20,000 IU/mL, and 5 (3.25%) >20,000 IU/mL. No mutations were detected in GENs B and A. The prevalence of HBV GENs B and A were 68.8% (n = 11) and 31.25% (n = 6), respectively.

Conclusion

GEN-B was more prevalent in comparison to GEN-A. The genetic diversity of HBV and distribution of its GENs and mutation improve the current knowledge of epidemiological, clinical and virological patterns of hepatitis B in this region, which help physicians to prescribe proper antiviral/interferon therapy according to current genotyping pattern.

Detection of HBV Genotype C in Hepatocellular Carcinoma Patients from North East India: a Brief Report

Background and Objectives: Newer genotypes of HBV have been reported from India. This study was aimed to determine the circulating genotypes of HBV in hepatocellular carcinoma patients from three different geographical locations of India. Methods: 141 HBV related HCC cases were included from three different hospitals across the country. Genotyping of HBV was performed by PCR using type specific primers specially designed in 70 cases. Samples of interest were confirmed by direct sequencing of the precore/core region of HBV genome. Results: Genotypes could be detected in 40 (57.14%) out of the 70 HBV DNA positive HCC cases by type specific primers. HBV genotype D was documented in 20 (50%), genotype A in 10 (25.0%) and genotype C in 10 (25.0%) of these HCC cases. Genotype C of HBV was detected only in the samples from North East India. No significant difference was observed for the biochemical profile. Conclusion: Although Genotype D is the major HBV genotype in India followed by A, detection of HBV genotypes C in HCC patients indicates a changing epidemiology of the virus in India that may require region based management of the virus.

INASL Position Statements on Prevention, Diagnosis and Management of Hepatitis B Virus Infection in India: The Andaman Statements

Hepatitis B Virus (HBV) infection is one of the major causes of morbidity, mortality and healthcare expenditure in India. There are no Indian consensus guidelines on prevention, diagnosis and management of HBV infection. The Indian National Association for Study of the Liver (INASL) set up a taskforce on HBV in 2016, with a mandate to develop consensus guidelines for diagnosis and management of HBV infection, relevant to disease patterns and clinical practices in India. The taskforce first identified contentious issues on various aspects of HBV management, which were allotted to individual members of the taskforce who reviewed them in detail. A 2-day round table discussion was held on 11th and 12th February 2017 at Port Blair, Andaman & Nicobar Islands, to discuss, debate, and finalize the consensus statements. The members of the taskforce reviewed and discussed the existing literature threadbare at this meeting and formulated the 'INASL position statements' on each of the issues. The evidence and recommendations in these guidelines have been graded according to the Grading of Recommendations Assessment Development and Evaluation (GRADE) system with minor modifications. The strength of recommendations (strong: 1, weak: 2) thus reflects the quality (grade) of underlying evidence (A, B, C, D). We present here the INASL position statements on prevention, diagnosis and management of HBV in India.

Current Scenario of Hepatitis B and Its Treatment in India

Hepatitis B is a significant public health problem in India, yet disease awareness is very low among the general population. The disease is mostly acquired horizontally, but the role of vertical transmission should not be underestimated. In spite of the fact that the majority of cases are e negative disease, most patients present in the advanced stage and even with hepatocellular carcinoma, the leading cause of which is hepatitis B. High-risk groups (especially tribals) also harbour significant disease burden and have a high prevalence of occult infection, supporting the potential of unknowingly spreading the disease. Findings on the relation of genotypes with disease severity or drug action have been conflicting. Though recently, oral antivirals with high genetic barrier to resistance have shown good viral suppression in the long term, e and s seroconversion is poor and relapse is universal upon therapy discontinuation. As no cure is possible with the currently available therapy, the target is long-term viral suppression by prolonged administration of oral antivirals; unfortunately, this leads to poor treatment adherence, which along with the high cost of therapy results in disease progression and spread of infection. At present, therefore, emphasis should be put on health education of the general and high-risk populations, along with health care workers to increase knowledge on such preventive measures as avoiding unsafe injection practices, high-risk sex, performing unnecessary injection and blood transfusion and providing proper screening of blood products; these efforts should be combined with intensive screening and aggressive vaccination programs, especially in high-risk groups and areas of high endemicity. Vaccination strategies are still below par and logistics should be developed for wider coverage; in addition, further research should be carried out on the efficacy and mode of usage for different types of vaccine.

Clinical Significance of Quantitative HBsAg Titres and its Correlation With HBV DNA Levels in the Natural History of Hepatitis B Virus Infection

BACKGROUND/OBJECTIVE

Quantification of serum hepatitis B antigen (HBsAg) is an important test that marks active infection with hepatitis B and helps in the prediction of the clinical outcome and management of hepatitis B virus (HBV) infection. Correlation with HBV DNA quantitative levels may help in developing strategies for antiviral treatment. This study is aimed to evaluate HBsAg titres in various phase of HBV infection in HBsAg positive patients, and its correlation with HBV DNA viral load levels.

METHODS

976 HBV related patients were analysed in this retrospective cross-sectional study. Patients were categorised on the basis of the phase of HBV infection: immune tolerant phase (IT, n = 123), immune clearance phase (IC, n = 192), low-replicative phase (LR, n = 476), and HBeAg-negative hepatitis (ENH, n = 185). HBsAg titres were quantified and correlated with HBV-DNA levels and clinical parameters.

RESULTS

Median HBsAg titres were different between each phases of HBV infection (P < 0.001): (4.62 log10 IU/ml), IC (3.88 log10 IU/ml), LR (2.76 log10 IU/ml) and ENH (2.94 log10 IU/ml). HBsAg and HBV DNA levels showed significant correlation in the whole group (r = 0.694, P < 0.001), and this was also observed in different phases of HBV infection. Strong correlation in IT phase (r = 0.603, P < 0.001) and IC phase (r = 0.523, P < 0.001), moderate in LR phase (r = 0.362, P < 0.001) and weak in ENH (r = 0.110, P = 0.04). No correlation was observed between serum HBsAg levels and biochemical parameters.

CONCLUSION

The study demonstrated significant difference in the median baseline values of serum HBsAg titres in different phases of HBV infection and provides additional information in understanding the natural history of HBV-infection.

Analysis of hepatitis B virus genotype changes in patients with chronic hepatitis B infection on tenofovir therapy

Antiviral therapy for chronic hepatitis B (CHB) is often required for prolonged periods. We investigated the instance of one HBV genotype switching to another during tenofovir therapy. Of the 67 patients, genotype A was present in 6 (8.9%), D in 43 (65.6%), C in 1 (1.5%), and mixed in 17 (23.8%) patients. Genotype changes were detected in 51 (76.1%) patients on therapy during a follow-up of 192 (range 52-312) weeks. Inter-genotype changes were seen in 17 (33.3%) and intra-genotype in 28 (55%) and both inter- and intra-genotype in 6 of 51 (11.7%) patients. The distribution of genotypes in patients achieving complete virological response was genotype D, 32/43 (74.4%); genotype A, 6/6 (100%); and mixed genotypes, 13/17 (76.47%). The cumulative time of genotype switch among genotype A was 12 months (range 6-18), in genotype D, 12 months (range 6-48), and mixed genotype, 18 months (range 6-24). The type of inter-genotype switch most frequently detected among genotype A1 was from A1 to D1 5/6 (83.3%), followed by mixed to genotype D3 7/13 (54%) and among intra-genotype changes, from D1 to D3 in 14/20 (70%). Pretreatment HBV genotype was the only factor predicting inter-genotype switches with genotype A or mixed genotypes more likely to undergo inter-genotype switches as compared to genotype D patients (OR 66.6 [13.6-327.0, P < 0.001]). Compared to genotype D, genotype A, and mixed genotypes are more inclined to switch while on tenofovir therapy. Genotypes tend to switch and select to a particular type possibly due to constant antiviral drug pressure. J. Med. Virol. 88:1364-1375, 2016. © 2016 Wiley Periodicals, Inc.

Distribution of hepatitis B virus genotype and cancer predicting precore and basal core promoter mutations

BACKGROUND

Chronic hepatitis B (CHB) infection which is associated with an increased risk of developing liver disease including cirrhosis and hepatocellular carcinoma. Viral factors that may increase the risk for HCC development include HBV DNA level, genotypes, and naturally occurring mutations such as hepatitis B virus precore (PC) (G1896A) and basal core promoter (BCP) A1762T/G1764A double mutations. HBV genotypes and subgenotypes can significantly influence HBeAg seroconversion rates, viremia levels, mutational patterns that could significantly influence the heterogeneity in clinical manifestations and even response to antiviral therapy.

METHOD

94 CHB infected individuals with detectable serum HBV DNA levels were studied. HBsAg, HBeAg, anti-HBc IgM antibody estimations were done by ELISA. HBV DNA estimation was done. The HBV genotypes were determined by TSP-PCR and 10 samples randomly selected for DNA sequencing. PC and BCP mutations were determined by DNA sequence analysis of core region.

RESULT

Of 94 study participant samples with detectable serum HBV DNA levels, 75 were successfully genotyped and sequenced for BCP/PC region. 30/75 (40%) harbored PC and BCP mutations. The total Double mutations of BCP at A1762T/G1764A nucleotide positions, and PC mutation at G1896A nucleotide position were seen in 29.3% and 21.3%, respectively. All 75 isolates were subtype D using TSP-PCR. However, by sequencing 2/10 were subtype A, while 8 were subtype D.

CONCLUSION

Our study reinforces that D is the predominant genotype in Indian population. It reveals that Indian CHB subjects have increased prevalence of BCP & PC mutations, which possibly may lead to development of HCC.

Molecular epidemiology of HBV infection in chronic hepatitis B virus infected patients in northeast India

The present study aimed to evaluate the molecular epidemiology of HBV in chronic HBV infected cases from northeast India (NEI), since scanty data are available from the region which has a predominant ethnically distinct tribal population. A total of 523 clinically diagnosed index chronic HBV infected cases and 172 asymptomatic patients (based on family screening) were enrolled with informed consent. Patients were stratified based on serology, imaging, pathology, and clinical data and grouped as chronic HBV and cirrhotic cohorts. Analysis for serum HBV DNA levels and HBV genotyping was performed, and was statistically co-related with disease severity. Males were more prone to chronic HBV infection. Majority of the patients who had Chronic HBV infection based on family screening were females (59.88%), majorly wives of index patients. Mean viral load in Chronic HBV patients was almost 4.5-folds higher than cirrhosis patients, and was significantly associated with e-antigen positive status(P < 0.001) in both groups. HBV genotype D was the most prevalent genotype (62.30%) in NEI. Mixed genotype infection of A + D was found from Assam, along with C + D cases (1.29%) cumulatively. There is a high prevalence of HBV genotype C (13.96%) in our studied cohort which was found to be associated with higher viral load(P = 0.018), e-antigen positivity(P = 0.043), and increased cirrhosis risk compared to Chronic HBV cases [OR = 1.670]. Family contacts in NEI are prone to infection with HBV and development of Chronic HBV. Higher presence of e-positive cases and genotype C along with the mixed genotypes in NEI is unique and of significance with reference to predisposition to disease severity and even response to antiviral therapy.

Distinct distribution pattern of hepatitis B virus genotype C and D in liver tissue and serum of dual genotype infected liver cirrhosis and hepatocellular carcinoma patients

Aims

The impact of co-infection of several hepatitis B virus (HBV) genotypes on the clinical outcome remains controversial. This study has for the first time investigated the distribution of HBV genotypes in the serum and in the intrahepatic tissue of liver cirrhotic (LC) and hepatocellular carcinoma (HCC) patients from India. In addition, the genotype-genotype interplay and plausible mechanism of development of HCC has also been explored.

Methods

The assessment of HBV genotypes was performed by nested PCR using either surface or HBx specific primers from both the circulating virus in the serum and replicative virus that includes covalently closed circular DNA (cccDNA) and relaxed circular DNA (rcDNA) of HBV from the intrahepatic tissue. The integrated virus within the host chromosome was genotyped by Alu-PCR method. Each PCR products were cloned and sequences of five randomly selected clones were subsequently analysed.

Results

HBV/genotype D was detected in the serum of all LC and HCC patients whereas the sequences of the replicative HBV DNA (cccDNA and rcDNA) from the intrahepatic tissue of the same patients revealed the presence of both HBV/genotype C and D. The sequences of the integrated viruses exhibited the solo presence of HBV/genotype C in the majority of LC and HCC tissues while both HBV/genotype C and D clones were found in few patients in which HBV/genotype C was predominated. Moreover, compared to HBV/genotype D, genotype C had higher propensity to generate double strand breaks, ER stress and reactive oxygen species and it had also showed higher cellular homologous-recombination efficiency that engendered more chromosomal rearrangements, which ultimately led to development of HCC.

Conclusions

Our study highlights the necessity of routine analysis of HBV genotype from the liver tissue of each chronic HBV infected patient in clinical practice to understand the disease prognosis and also to select therapeutic strategy.

Mutation profiling of the hepatitis B virus strains circulating in North Indian population

AIMS

The aim of this study was to investigate the genomic mutations in the circulating Hepatitis B virus strains causing infection in the Indian population. Further, we wanted to analyze the biological significance of these mutations in HBV mediated disease.

METHODS

222 HBsAg positive patients were enrolled in the study. The genotype and mutation profile was determined for the infecting HBV isolate by sequencing overlapping fragments. These sequences were analyzed by using different tools and compared with previously available HBV sequence information. Mutation Frequency Index (MFI) for the Genes and Diagnosis group was also calculated.

RESULTS

HBV Genotype D was found in 55% (n = 121) of the patient group and genotype A was found in 30% (n = 66) of samples. The majority (52%) of the HBV-infected individuals in the present study were HBeAg-negative in all the age groups studied. Spontaneous drug associated mutations implicated in resistance to antiviral therapy were also identified in about quarter of our patients, which is of therapeutic concern. The MFI approach used in the study indicated that Core peptide was the most conserved region in both genotypes and Surface peptide had highest mutation frequency. Few mutations in X gene (T36A and G50R) showed high frequency of association with HCC. A rare recombinant strain of HBV genotype A and D was also identified in the patient group.

CONCLUSIONS

HBV genotype D was found out to be most prevalent. More than half of the patients studied had HBeAg negative disease. Core region was found to be most conserved. Drug Associated mutations were detected in 22% of the patient group and T36A and G50R mutations in X gene were found to be associated with HCC.

Emergence of hepatitis B virus genotype f in aligarh region of north India

Introduction. HBV genotypes and subtypes are useful clinical and epidemiological markers. In this study prevalent HBV genotypes were assessed in relation to serological profile and clinical status. Material & Methods. 107 cases of HBV were genotyped. Detailed clinical history was elicited from them. HBsAg, HBeAg, anti-HBs, anti-HBe, and anti-HBc-IgM were assessed. HBV genotyping was performed using Kirschberg's type specific primers (TSP-PCR), heminested PCR, and Naito's monoplex PCR. Nucleotide sequencing was performed. Results. A total of 97 (91%) were genotyped following the methods of Kirschberg et al./Naito et al. Genotype D was by far the most prevalent genotype 91 (85.04%) in this region. A surprising finding was the detection of genotype F in 5 (4.67%) of our patients. Genotype A strangely was observed only in one case. In 85.7% genotype D was associated with moderate to severe liver disease, 43.9% HBeAg, and 18.7% anti-HBc-IgM positivity. Majority of genotype F (80%) was seen in mild to moderate liver disease. It was strongly associated with HBeAg 60% and 20% anti-HBc-IgM positivity. Conclusion. Emergence of genotype F in India merits further study regarding its clinical implications and treatment modalities. Knowledge about HBV genotypes can direct a clinician towards more informed management of HBV patients.

Further evidence of hepatitis B virus genotype I circulation in Northeast India

Hepatitis B virus (HBV) genotypes have known to show a geographical pattern in their distribution and have been used to trace the migration of populations from geographically distant regions. Novel recombinants between HBV genotypes A, G and C referred as genotype I has been recently reported from Eastern India. In our investigation to characterise antiviral resistance mutations, we identified a rare case of HBV genotype I infection in chronic hepatitis B subject. We encountered confounding results of this emerging genotype 'designated as genotype G' in three widely used HBV sequence database for genotype determination. The recombinant fragment of genotype G largely occupies the surface gene sequence of the newly identified genotype I and could hence lead to misclassification of genotype I. Additionally, recombination analysis of the generated sequences in Simplot and jpHMM model showed two different patterns of recombination events. In conclusion, the increasing recognition of genotype I in this population suggests that further studies may reveal uncommon genotypes from other geographically distant regions. Our observation of potential genotype I misclassification despite the use of public HBV sequence database and other recombination analysis tools highlights the need for updating and validating public sequence domains of diagnostic importance.

Meta-analysis: The association of hepatitis B virus genotypes and hepatocellular carcinoma

BACKGROUND

A meta-analysis on the risk of hepatocellular carcinoma (HCC) among hepatitis B virus (HBV) genotypes is warranted as the current data are conflicting.

AIM

To investigate the relative risk of HCC among the four major HBV genotypes (A-D).

METHODS

A meta-analysis was performed based on literature search from electronic databases and bibliography between 1950 and 2012. All abstracts with keywords 'hepatitis B', 'hepatocellular carcinoma' and 'genotype' were screened. Studies were included if they reported HBV genotype as an exposure and HCC as an outcome.

RESULTS

Nine hundred and eighty-eight abstracts were found through literature search, among them 43 studies were eligible for this meta-analysis. A total of 14,545 patients with an average age of 43 years were included; 71% were male patients and 17% had cirrhosis. In 33 studies, HCC was found in 1541/6060 (25%) genotype C vs. 550/4417 (12%) genotype B HBV-infected patients [odds ratio (OR) = 2.05, 95% confidence interval (CI) = 1.52-2.76, P < 0.001]. No difference in the risk of HCC was found among genotype A (71/517, 14%) vs. genotype D (170/1506, 11%) HBV-infected patients in 14 studies (OR = 0.94, 95% CI = 0.67-1.32). In 10 studies, the risk of HCC was also found higher among genotype C (498/1659, 30%) than genotype A&D (103/1403, 7%) HBV-infected patients (OR = 2.34, 95% CI = 1.63-3.34, P < 0.001). Subgenotype Ce and Cs HBV-infected patients had similar risk on HCC (OR = 1.13, 95% CI = 0.76-1.67, P = 0.54). On funnel plot analysis, there was no significant publication bias in all comparisons.

CONCLUSION

Genotype C hepatitis B virus is associated with a higher risk of hepatocellular carcinoma than other major hepatitis B virus genotypes.

Subgenotype D5, BCP and MHR mutations in hepatic complications among hepatitis B virus infected patients from Orissa, India

The study was undertaken to investigate the clinical implications of hepatitis B virus (HBV) genotypes, basal core promoter (BCP), precore (PC) and surface gene mutations in HBV infected patients from Orissa, southeastern India. HBV infections were identified by serology testing and HBV DNA amplification by polymerase chain reaction among the 152 patients. After sequencing, surface gene mutation were studied by sequence analysis as well as by using BLOSUM scores and BCP mutations were studied only by sequence analysis. A high proportion of HBV/D5 (66.0%) was found among the study samples having significant relation with liver cirrhosis (LC) and hepatocellular carcinoma (HCC) patients (p<0.05). The BCP mutation, TA (81.4%) and C1753/TA (75.0%) was found in significant proportion (p<0.05) among HCC cases and in fact a gradual increase in these mutations were noted between inactive carriers (IC) to HCC group and also showed higher viral load. An increasing trend of major hydrophilic region (MHR) mutations in S gene was also observed from IC (56.0%) to chronic liver disease (CLD) (60.4%) to LC (72.4%) to HCC (95.0%) patients. In conclusion, our study suggests that the predominant HBV subgenotype HBV/D5 with high viral load and BCP mutations (double and triple) and high mutations in MHR region was significantly associated with advanced liver disease (LC and HCC) and might act as predictor of severe hepatic complications.

Hepatitis B virus genotyping: is the time ripe for routine clinical use?

Hepatitis B is one of the major causes of end-stage liver disease and liver cancer worldwide. A number of host and viral factors influence the disease course and outcomes. One such viral factor is hepatitis B virus (HBV) genotypes. There are eight major HBV genotypes described from various geographic regions of the world. Although direct sequencing appears to be the gold standard for HBV genotyping, it is expensive and laborintensive and therefore cannot be applied for routine clinical use. The newer molecular methods including serotyping have made genotyping easier and simple to apply to large number of samples rapidly. The data collected mainly over the last decade have suggested that HBV genotypes may have a bearing over the natural course of the disease and its response to therapy. This review summarizes the available literature and highlights how genotyping could be incorporated into routine clinical practice in order to improve delivery of care to HBV-infected individuals.

Viral hepatitis in India

Hepatitis in India is caused mainly by hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis E virus (HEV). HAV infection occurs frequently in children, though in parts of India there is an evolving epidemiology. HEV is the most common cause of acute sporadic hepatitis in India and has been associated with several large-scale epidemics in the past. India belongs to the intermediate endemicity zone for HBV carriers. HBV is the major cause of chronic liver disease and liver cancer. Horizontal transmission of HBV plays an important role. Genotypes D, A, and C have been reported in India. HCV is transmitted mainly through suboptimal blood banking and injection practices in India. Genotype 3 is the most predominant, followed by genotype 1.

Prevalence of Genotype D and Precore/Core Promoter Mutations in Hepatitis B Virus-infected Population of North India

Hepatitis B virus (HBV) isolates (21) from Punjab (North India) were studied for genotype distribution and precore/core promoter mutations. Assays of alanine aminotransaminase (ALT) and HBeAg were performed in all isolates. Genotypes were determined in all the samples by restriction fragment length polymorphism and the precore/core promoter mutations were studied by amplification and by direct sequencing of precore/core promoter region. Sixty-two percent of the isolates had higher ALT levels and 57% of the isolates were HBeAg negative. It was observed that 90% of the isolates were HBV D genotype (subgenotype D1 and D2) and 10% of the isolates were HBV A genotype (subgenotype A1). Amplification and sequencing of the precore/core promoter region showed 1762(A-T) and 1764(G-A) mutations in 29% and 19% of the isolates, respectively. 1809(C/T) mutation was observed in 71% of the isolates under study. Novel precore and core promoter mutations like 1690(A), 1695(A/T/G), 1700(A/C), 1703(c), 1850(A) and 1915(A/G) were observed in HBV-infected population of the state of Punjab (North India). Deletion and insertional mutations were also observed in some patients. (J CLIN EXP HEPATOL 2011;1:73-76).

Distribution of Hepatitis B virus genotypes among healthy blood donors in eastern part of North India

AIM

We evaluated the distribution HBV genotypes among non-remunerated healthy blood donors in eastern North India.

MATERIALS AND METHODS

During screening of donated blood, 176 consecutive HBsAg positive, samples comprised the study. HBV-DNA was quantitative detected in 150 samples by PCR. HBV genotype was determined by identifying genotype-specific DNA band using nested PCR.

RESULTS

Majorities were of age group 31-40 yrs (65.3%). Males (92.7%) outnumbered females (7.3%) and were HbeAg-negative HBsAg carriers. Over all, genotype-A was the most prevalent (54%) followed by D (21.3%). We did not find genotype-G and H. Districts under study, divided into four zones: Zone-I genotype-A was most common (62.3%) followed by D (18.8%); Zone-II genotype-C (41.2%) was more frequent followed by D (20.6% and A (17.7%). Zone-III in adjoining Bihar state close to Zone-I, A was more prevalent (81.8%) followed by B and C (9.1%). In Zone-IV adjoining Zone- II had genotype-A (100%) only. Genotype-D had more sporadic distribution. Genotype-E and F were prevalent in Zone I and II (3/150, 2%).

CONCLUSIONS

Among blood donors HBV genotype-A followed by D was the most prevalent in eastern North India. Genotype-A had pattern of distribution signifying common focus, while D was more sporadic and C had single large pocket (Zone-II) probably common focus but restricting to particular area. Evidences are suggestive of association of HBV genotype in liver dysfunction. An effective treatment and preventive strategies based of genotypes will reduce the disease burden and increase the blood safety.

Clinical profile, genotype and management updates of hepatitis B virus

Hepatitis B virus (HBV) is a well known agent of acute and chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Around 400 million people worldwide carrier of HBV of which more than 250 million reside in Asia, and 1-2 million people have died from it. It has a partially double-stranded DNA, having 3.2-kb genome size and replicate via reverse transcription of RNA intermediate. In the natural history or during the antiviral therapy of chronic HBV infection, seroconversion from HBeAg to anti-HBeAg is usually accompanied by a decrease in viral replication and remission of liver disease. Based on genomic sequence data HBV is classified into eight genotypes A-H and four major serotypes ayw, ayr, adw and adr on the basis of complete genome and S gene sequence analysis. Genotypes and serotypes are useful tools in understanding the epidemiology of HBV infection. HBV genotypes have distinct geographical distributions. The HBV variants appear during HBeAg seroconversion and they bring mutations in the precore region (PC) that prevent HBeAg synthesis. Another common HBeAg variant is the basal core promoter mutant (BCP) characterized by point mutation in the promoter of both HBeAg mRNA and core protein mRNA. The most frequent core promoter mutation is the double A1762T and G1764A nucleotide exchange, which results in a substantial decrease in HBeAg expression but enhanced viral genome replication. The approved antiviral drugs such as Interferon, lamivudine, adefovir dipivoxil, entecavir and telbivudine for purpose of treating chronic HBV infection is to prevent or stop the progression of liver injury by suppressing viral replication or eliminating infection. Sustained losses of viral markers of active viral replication (HBeAg and HBV DNA) are the standard end point of the therapies.

Distribution of hepatitis B virus genotypes and its association with severity of liver disease in patients with chronic hepatitis B in uttar pradesh, India

The present study was designed to investigate the distribution of genotypes and its association with severity of liver disease in patients with Chronic Hepatitis B (CHB) in Uttar Pradesh, India. One hundred five HBsAg positive patients were selected for the study. The DNA was extracted by using pure viral DNA extraction kit. The genotype of Hepatitis B virus (HBV) was identified by using polymerase chain reaction- based restriction fragment length polymorphism (PCR-RFLP) method, by using AvaII and DpnII restriction enzyme to see the different patterns of cleavage that would occur at this specific site. Among 105 HBsAg positive chronic liver disease patients 58 patients were positive for HBeAg and 47 samples were HBeAg negative. Genotyping was done successfully in 91 samples. Genotype A was identified in 22% and genotype D in 78% CHB patients. Genotype A showed elevated liver enzymes much more than genotype D. The Child Pugh classification of 20 patients with genotype A was class A (n = 2), B (n = 9), C (n = 9) and of genotype D was class A (n = 13), B (n = 50) and C (n = 8). In conclusion our results showed that Genotype D was the commonest genotype in Uttar Pradesh, whereas genotype A had significantly more elevated ALT/AST levels than genotype D. (P < 0.05). Child Pugh Grade B was significantly more in patients with genotype D, whereas Child Pugh Grade C was more in genotype A.

Variations in the functional domain of basal core promoter of hepatitis B virus among Eastern Indian patients with prevalence of genotypes A, C, and D among the same ethnic population

Mutations in the basal core promoter (BCP) and precore (PC) regions are associated with persistent and intermittently high hepatitis B virus (HBV) replication in several patients. The variability in the functional domains of BCP and PC region of HBV and their association with disease progression and clinical outcome were assessed in Eastern India, an unique region where three HBV genotypes, A, D, and C are prevalent among the same ethnic group. PCR amplification and direct sequencing of BCP and PC region was done on sera obtained from 130 HBsAg positive subjects with different clinical presentations. Associations of the apparent risk factors with clinical advancement were evaluated by statistical methods including multiple logistic regression analyses (MLR). HBV genotype A was present in 33.08%, C in 25.38%, and D in 41.54% cases. Genotypes A and C were associated with higher rate of T1762/A1764 mutations than the most predominant genotype D. HBeAg negative state was associated with considerably higher rate of C1753 mutation. T1762/A1764 along with C1753 was common among cirrhosis and T1762/A1764 without C1753 was frequent among chronic liver disease cases. No significant association was found between A1896 point mutation and clinical status. Multivariate analysis revealed that T1762/A1764 double mutation, HBV/A, age ≥25 years, C1753 and A1899 were critical factors for clinical advancement while age ≥25 years and C1753 as significant predictor for cirrhosis in comparison with chronic liver disease. In conclusion, the analysis of the BCP variability may help in monitoring the progression towards advanced liver disease in Eastern Indian patients.

Anti-hepatitis B core antigen testing with detection and characterization of occult hepatitis B virus by an in-house nucleic acid testing among blood donors in Behrampur, Ganjam, Orissa in southeastern India: implications for transfusion

Background

Occult hepatitis B virus (HBV) infection might transmit viremic units into the public blood supply if only hepatitis B surface antigen (HBsAg) testing is used for donor screening. Our aim was to evaluate the prevalence of occult HBV infection among the HBsAg negative/antiHBc positive donations from a highly HIV prevalent region of India.

Methods

A total of 729 HBsAg negative donor units were included in this study. Surface gene and precore region were amplified by in house nucleic acid test (NAT) for detection of occult HBV infection and surface gene was analyzed after direct sequencing.

Results

A total of 220 (30.1%) HBsAg negative donors were antiHBc positive, of them 66 (30%) were HBV DNA positive by NAT. HBV DNA positivity among 164 antiHBc only group, was 27.1% and among 40 antiHBs positive group was 30.0%. HBV/D (93.3%) was predominant and prevalence of both HBV/C and HBV/A was 3.3%. Single or multiple amino acids substitutions were found in 95% samples.

Conclusion

Thus, a considerable number of HBV infected donors remain undiagnosed, if only HBsAg is used for screening. Addition of antiHBc testing for donor screening, although will lead to rejection of a large number of donor units, will definitely eliminate HBV infected donations and help in reducing HBV transmission with its potential consequences, especially among the immunocompromised population. The HBV genetic diversity found in this donor population are in accordance with other parts of India.

Geographical and genetic diversity of the human hepatitis B virus

Hepatitis B virus (HBV) is one of the most widely distributed viruses that infect humankind. Distinct clinical and virological characteristics of the HBV-infection have been reported in different geographical parts of the world and are increasingly associated with genetic diversity of the infecting virus. HBV is classified into genotypes and subgenotypes that are associated with ethnicity and geography. The genetic diversity of HBV in its various aspects has been the subject of extensive investigations during the last few decades. Since molecular epidemiology research tools have become widely available, the number of new publications in this field has grown exponentially. This review summarises the recent publications on the geographical distribution of genetic variants of HBV, and proposes updated criteria for the identification of new genotypes and subgenotypes of the virus.

Spontaneous increases in alanine aminotransferase levels in asymptomatic chronic hepatitis B virus-infected patients

BACKGROUND & AIMS

No information is available about the frequency or factors that predict spontaneous increases in alanine aminotransferase (ALT) levels in asymptomatic Indian patients with chronic hepatitis B virus (HBV) infection who are HB e antigen (HBeAg) negative and have normal ALT levels.

METHODS

We followed 217 asymptomatic patients with chronic HBV who were HBeAg negative, anti-HBe antigen (anti-HBe) positive, and had normal ALT levels. Spontaneous increases in ALT levels (ALT flares) were considered to be >2-fold the upper limit of normal (ULN) and were accompanied by HBV DNA levels>or=10(5) copies/mL or a 100-fold increase from the previously measured level.

RESULTS

During a median follow-up period of 69.0 months, spontaneous ALT flares occurred in 43 patients (an annual rate of 4.3%), with cumulative probabilities of 10.8% and 47.3% after 5 and 10 years, respectively. Based on multinomial logistic regression, the probability of an ALT flare correlated with age>or=30 years at presentation (odds ratio [OR], 5.31; 95% confidence interval [CI]: 1.53-18.39; P=.008), male sex (OR, 4.54; 95% CI: 1.01-20.76; P=.05), and presence of a precore mutation (OR, 10.99; 95% CI: 3.67-32.92; P<.001). The median time to spontaneous ALT flare after enrollment was 25 months (range, 1-128 months; 10th percentile=3.4 months).

CONCLUSIONS

In asymptomatic patients with chronic HBV infection who have normal ALT levels and are HBeAg negative, the annual rate of ALT flares was 4.3%. Precore mutants, male sex, and age>or=30 years at presentation are independent predictors for an ALT flare. A follow-up every 3 months can capture up to 90% of flares and would help identify patients who require antiviral therapy.

Frequency and distribution of hepatitis B virus genotypes among eastern Indian voluntary blood donors: Association with precore and basal core promoter mutations

AIM

To screen hepatitis B virus (HBV) genotypes and associated basal core promoter (BCP; T1762/A1764) and precore (PreC; A1896) mutations among the HBV surface antigen (HBsAg) positive voluntary blood donors in eastern India.

METHODS

HBV genotypes, BCP and PreC mutations of 141 HBsAg positive voluntary blood donors were determined by the restriction fragment length polymorphism (RFLP) method and a phylogenetic tree was constructed from surface (S) gene region sequences of representative HBsAg positive donors to confirm the results.

RESULTS

HBV/D was the most predominant (79, 56.0%) genotype followed by HBV/C (33, 23.4%) and HBV/A (29, 20.6%). HBV/C infected blood donors are mostly young (18-25 years). The occurrence of BCP mutation was found to be significantly higher in HBV/C (24, 72.7%) than in HBV/A (7, 24.1%, P < 0.001) and HBV/D (17, 21.5%, P < 0.001), whereas PreC mutation was more frequent in HBV/D (28, 35.4%) than in HBV/C (9, 27.3%). However, the simultaneous presence of BCP and PreC mutations was more common in HBV/C (8/33, 24.2%), followed by HBV/D (6/79, 7.6%).

CONCLUSION

In addition to HBV/D and HBV/A, a significant proportion of HBV/C (23.4%) was also present among the voluntary blood donors from eastern India, most frequently in the 18-25 year age group. BCP mutation was more common in HBV/C infected donors.

Genotype D amongst injection drug users with acute hepatitis B virus infection in British Columbia

The eight genotypes of hepatitis B virus (HBV) exhibit distinct geographical distributions. This study identified HBV genotypes and transmission modes associated with acute infection in British Columbia (BC), Canada, from 2001 to 2005. Seventy cases of acute HBV in BC were identified from laboratory reports using a standardized case definition. Interviews for risk factors and hepatitis history were conducted for each case. HBV genotypes were determined by BLAST comparison analysis of the surface (S) or preS gene sequence. To illustrate the distribution of genotypes identified amongst acute cases in BC, an annotated map was produced showing the global occurrence of HBV genotypes. The majority of acute HBV cases occurred in Caucasian, Canadian-born males, with 30% of cases reporting injection drug use (IDU) and 21% reporting incarceration. The most common genotype observed was genotype D (62.9%), followed by genotypes A (18.6%), C (11.4%), B (4.3%), and E (1.4%). A significant association was observed between Genotype D and IDU (P = 0.0025) and previous incarceration (P = 0.0067). Phylogenetic analysis of the S gene sequence demonstrated identical or high genetic relatedness amongst genotype D viral strains (86% sub-genotype D3), thus verifying transmission clustering amongst BC injection drug users. The association between acute HBV genotype and reported transmission modes has not been previously described in North America. Tracking of genotypes can help identify disease transmission patterns and target at-risk populations for preventive immunization.

An overview of molecular epidemiology of hepatitis B virus (HBV) in India

Hepatitis B virus (HBV) is one of the major global public health problems. In India, HBsAg prevalence among general population ranges from 2% to 8%, placing India in intermediate HBV endemicity zone and the number of HBV carriers is estimated to be 50 million, forming the second largest global pool of chronic HBV infections. India is a vast country, comprised of multiracial communities with wide variations in ethnicity and cultural patterns, which is attributable to its geographical location, gene influx due to invasion and/or anthropological migrations in the past. Moreover, recent increase in trade, trafficking and use of illicit drugs has also considerably influenced the epidemiology of HBV, specifically in the eastern and north eastern parts of India. However, data on the molecular epidemiology of HBV in India is scanty. HBV genotypes A and D have been well documented from different parts of mainland India. Interestingly, in addition to genotypes A and D, genotype C having high nucleotide similarity with south East Asian subgenotype Cs/C1 strain, have been detected exclusively from eastern Indian HBV carriers, suggesting a recent introduction. Thus, compared to other parts of India, the molecular epidemiology of HBV is naturally distinct in eastern India. Very recently, taking the advantage of circulation of three distinct HBV genotypes within the population of eastern India, different aspects of HBV molecular epidemiology was studied that revealed very interesting results. In this study, the clinical significance of HBV genotypes, core promoter and precore mutations, possible routes of introduction of HBV genotype C in eastern India, the clinical implications of x gene variability, prevalence of the AFB₁ induced p53 gene codon 249 mutation, the transmission potentiality of HBV among asymptomatic/inactive or occult HBV carriers and the genetic variability of HBV persisting in the PBL was investigated. In this manuscript, the information available on the molecular epidemiology of HBV in India has been reviewed and the results of studies among the eastern Indian population have been summarised.

Identification and characterization of genotype A and D recombinant hepatitis B virus from Indian chronic HBV isolates

AIM: To confirm the presence of recombination, full-length hepatitis B virus (HBV) from chronic patients was sequenced and analyzed.

METHODS: Full-length HBV genomes from 12 patients were amplified and sequenced in an automated sequencer. Phylogenetic analysis was carried out on full-length, Core and preS2/Surface regions using MEGA software. SimPlot Boot Scanning and amino acid sequence analysis were performed for confirmation of recombination.

RESULTS: Eight patients were infected with genotype D strain; one patient with genotype A and three patients had genotype A and D recombination; two of them had cirrhosis and one had hepatocellular carcinoma. Phylogenetic analysis of core and preS2/surface regions separately showed evidence of genotype A and D recombination. The breakpoints of recombination were found to be at the start of preS2 and at the end of surface coding regions.

CONCLUSION: We identified and characterized recombinant A and D genotype HBV in hepatitis B surface antigen (HBsAg)-positive patients.

Hepatitis B virus genotypes: natural history and implications for treatment

There are eight different genotypes named A-H. Genotypes have distinct geographic distribution in different regions of the world. There exists a difference in the disease profile between different genotypes. Genotype A compared with D, and B compared with C have earlier hepatitis B e-antigen seroconversion and less severe liver disease. However, genotypes are closely linked with core promoter and precore mutations. This may have a confounding effect on the association of genotypes with disease progression. Patients with genotype A compared with D and B compared with C have a better treatment response to IFN-alpha. However, there are no differences in the treatment response and rate of emergence of drug-resistant hepatitis B virus between different genotypes to nucleoside/nucleotide analog therapy.

The association of complex liver disorders with HBV genotypes prevalent in Pakistan

Background

Genotyping of HBV is generally used for determining the epidemiological relationship between various virus strains and origin of infection mostly in research studies. The utility of genotyping for clinical applications is only beginning to gain importance. Whether HBV genotyping will constitute part of the clinical evaluation of Hepatitis B patients depends largely on the availability of the relevance of the evidence based information. Since Pakistan has a HBV genotype distribution which has been considered less virulent as investigated by earlier studies from south East Asian countries, a study on correlation between HBV genotypes and risk of progression to further complex hepatic infection was much needed

Methods

A total of 295 patients with HBsAg positive were selected from the Pakistan Medical Research Council's (PMRC) out patient clinics. Two hundred and twenty six (77%) were males, sixty nine (23%) were females (M to F ratio 3.3:1).

Results

Out of 295 patients, 156 (53.2%) had Acute(CAH), 71 (24.2%) were HBV Carriers, 54 (18.4%) had Chronic liver disease (CLD) Hepatitis. 14 (4.7%) were Cirrhosis and HCC patients. Genotype D was the most prevalent genotype in all categories of HBV patients, Acute (108), Chronic (39), and Carrier (53).

Cirrhosis/HCC (7) were HBV/D positive. Genotype A was the second most prevalent with 28 (13%) in acute cases, 12 (22.2%) in chronics, 14 (19.7%) in carriers and 5 (41.7) in Cirrhosis/HCC patients. Mixed genotype (A/D) was found in 20 (12.8%) of Acute patients, 3 (5.6%) of Chronic and 4 (5.6%) of carriers, none in case of severe liver conditions.

Conclusion

Mixed HBV genotypes A, D and A/D combination were present in all categories of patients except that no A/D combination was detected in severe conditions. Genotype D was the dominant genotype. However, genotype A was found to be more strongly associated with severe liver disease. Mixed genotype (A/D) did not significantly appear to influence the clinical outcome.

High level of genetic heterogeneity in S and P genes of genotype D hepatitis B virus

The genetic heterogeneity of hepatitis B virus (HBV) genotypes and subgenotypes was investigated by directly sequencing amplified PreS, S and P genes of HBV isolates obtained from the plasma of 99 subjects with chronic HBV infection. Genotype D showed the greatest intragenotypic and intrasubgenotypic divergence: in particular, the a determinant was mutated in 58.2% of the genotype D patients, two of whom showed prototypic vaccine-induced escape mutants at codon 145. Moreover, five sites under significant positive selection were found in the S protein of the D isolates: one in the a determinant and four in the highly hydrophobic C terminal. Our results suggest that careful surveillance of vaccine-induced escape mutants should be considered in populations with highly frequent genotype D infections, and raise questions concerning the possible relationship between the genetic heterogeneity, host immunity and pathogenicity of this HBV genotype.