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

Identification of hepatitis B virus genotypes detected in Lahaul & Spiti district of Himachal Pradesh, India

Background & objectives

Infection by hepatitis B virus (HBV) results in acute or chronic hepatitis. Based on sequence differences of eight per cent or more, HBV is divided into 10 genotypes (A to J) and 35 sub-genotypes. Molecular characterization of the circulating HBV genome has helped in understanding the epidemiology and its clinical importance. Spiti valley in Himachal Pradesh, which shares its border with Tibet, is one of the most HBV prevalent areas in India. Since information about the circulating genotype/s of HBV in this area is limited, this study was conducted to identify the circulating HBV genotypes.

Methods

The surface and partial reverse transcriptase gene regions were sequenced using 14 hepatitis B surface antigen-positive samples.

Results

Out of the 14 hepatitis B surface antigen-positive samples 11 sample gave quality sequence for further analysis. All the 11 samples belonged to subtype ayw2. The phylogenetic and recombination analysis revealed that five out of 11 samples were of genotype CD1 and the rest six were of genotype D3.

Interpretation & conclusions

The CD1 recombinant sub-genotype might have immigrated during past or present transcontinental migration between the adjacent countries. Further studies using full-genome sequencing and high sample size will be helpful to understand this epidemiology and to combat the high prevalence of HBV in the area.

Thalassemia Patients from Baluchistan in Pakistan Are Infected with Multiple Hepatitis B or C Virus Strains

There are an estimated 2,000 children with β-thalassemia in the province Baluchistan of Pakistan. These children are at high risk of acquiring transfusion-transmitted infections (TTIs) due to their need of regular blood transfusions for survival. Therefore, we investigated the frequencies of TTIs among these multi-transfused patients in a region where the WHO guidelines for blood safety are not always followed. Sera from 400 children (mean age 7.7 ± 4.70 years) treated at two thalassemia centers in Baluchistan were investigated for TTIs. Eleven (2.8%) were hepatitis B surface antigen positive, and 72 (18.3%) had anti-hepatitis C virus (HCV), two of which were infected with both viruses. Only 22% of the children had been reached by the program for universal hepatitis B virus (HBV) vaccination which started in 2004. Half (51%) of the HCV infected had also been HBV infected. The HBV- and HCV-infected patients were older and had received more blood transfusions than the uninfected patients (P < 0.001). Molecular characterization of the viral strains revealed the presence of several genetically different strains in at least three HBV- and seven HCV-infected children. This is the first study to demonstrate infections with multiple HBV or HCV strains simultaneously infecting thalassemia patients. These may become the source for new emerging recombinant viruses of unknown virulence. The high prevalence of anti-HCV-positive children, and the presence of HBV infections among children who should have been vaccinated, highlights an urgent need for improvements of blood safety in this region of Pakistan.

Reactivation of hepatitis B after liver transplantation: Current knowledge, molecular mechanisms and implications in management

Chronic hepatitis B (CHB) is a major global health problem affecting an estimated 350 million people with more than 786000 individuals dying annually due to complications, such as cirrhosis, liver failure and hepatocellular carcinoma (HCC). Liver transplantation (LT) is considered gold standard for treatment of hepatitis B virus (HBV)-related liver failure and HCC. However, post-transplant viral reactivation can be detrimental to allograft function, leading to poor survival. Prophylaxis with high-dose hepatitis B immunoglobulin (HBIG) and anti-viral drugs have achieved remarkable progress in LT by suppressing viral replication and improving long-term survival. The combination of lamivudine (LAM) plus HBIG has been for many years the most widely used. However, life-long HBIG use is both cumbersome and costly, whereas long-term use of LAM results in resistant virus. Recently, in an effort to develop HBIG-free protocols, high potency nucleos(t)ide analogues, such as Entecavir or Tenofovir, have been tried either as monotherapy or in combination with low-dose HBIG with excellent results. Current focus is on novel antiviral targets, especially for covalently closed circular DNA (cccDNA), in an effort to eradicate HBV infection instead of viral suppression. However, there are several other molecular mechanisms through which HBV may reactivate and need equal attention. The purpose of this review is to address post-LT HBV reactivation, its risk factors, underlying molecular mechanisms, and recent advancements and future of anti-viral therapy.

Whole-gene analysis of two groups of hepatitis B virus C/D inter-genotype recombinant strains isolated in Tibet, China

Tibet is a highly hepatitis B virus (HBV) endemic area. Two types of C/D recombinant HBV are commonly isolated in Tibet and have been previously described. In an effort to better understand the molecular characteristic of these C/D recombinant strains from Tibet, we undertook a multistage random sampling project to collect HBsAg positive samples. Molecular epidemiological and bio-informational technologies were used to analyze the characteristics of the sequences found in this study. There were 60 samples enrolled in the survey, and we obtained 19 whole-genome sequences. 19 samples were all C/D recombinant, and could be divided into two sub-types named C/D1 and C/D2 according to the differences in the location of the recombinant breakpoint. The recombination breakpoint of the 10 strains belonging to the C/D1 sub-type was located at nt750, while the 9 stains belonging to C/D2 had their recombination break point at nt1530. According to whole-genome sequence analysis, the 19 identified strains belong to genotype C, but the nucleotide distance was more than 5% between the 19 strains and sub-genotypes C1 to C15. The distance between C/D1with C2 was 5.8±2.1%, while the distance between C/D2 with C2 was 6.4±2.1%. The parental strain was most likely sub-genotype C2. C/D1 strains were all collected in the middle and northern areas of Tibet including Lhasa, Linzhi and Ali, while C/D2 was predominant in Shannan in southern Tibet. This indicates that the two recombinant genotypes are regionally distributed in Tibet. These results provide important information for the study of special HBV recombination events, gene features, virus evolution, and the control and prevention policy of HBV in Tibet.

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.

Hepatitis B virus intergenotypic recombinants worldwide: An overview

Novel variants generated by recombination events between different hepatitis B virus (HBV) genotypes have been increasingly documented worldwide, and the role of recombination in the evolutionary history of HBV is of significant research interest. In the present study, large-scale data retrieval and analysis on HBV intergenotypic recombinant genomes were performed. The geographical distribution of HBV recombinants as well as the molecular processes involved in recombination were examined. After review of published data, a total of 436 complete HBV sequences, previously identified as recombinants, were included in the recombination detection analysis. About 60% of HBV recombinants were B/C (n=179) and C/D (n=83) hybrids. A/B/C, A/C, A/C/G, A/D, A/E, A/G, B/C/U (U=unknown genotype), C/F, C/G, C/J, D/E, D/F, and F/G hybrids were additionally identified. HBV intergenotypic sequences were reported in almost all geographical regions with similar circulation patterns as their original genotypes, indicating the potential for spreading in a wide range of human populations and developing their own epidemiology. Recombination breakpoints were non-randomly distributed in the genome, and specific favored sites detected, such as within nt 1700-2000 and 2100-2300 regions, which displayed a statistically significant difference in comparison with the remaining genome. Elucidation of the effects of recombination events on the evolutionary history of HBV is critical to understand current and future evolution trends.

Distribution and epidemiologic trends of HBV genotypes and subtypes in 14 countries neighboring china

BACKGROUND

The number of cases of HBV infection reported by the WHO for each district and country is positively correlated with the number of HBV sequences in the database isolated from the corresponding district and country.

OBJECTIVES

This study determined distribution characteristics of HBV genotypes and subtypes in 14 countries neighboring China. The progress made in genomic research involving HBV was also reviewed.

MATERIALS AND METHODS

Nine hundred fifty-one complete genome sequences of HBV from 14 countries neighboring China were selected from NCBI. The sequence-related information was analyzed and recorded. One hundred seventy-two sequences of HBV genotype B were screened for alignment using DNA star and MEGA 5.1.

RESULTS

Dominant HBV genotypes in the countries neighboring China were genotypes B, C and D and dominant subtypes were adw2 and adrq+. The association between genotype and serotype of HBV in these countries was shown to differ from previous research results. As shown by sequence alignment, the sequence divergence between five subgenotypes (B3, B5, B7, B8 and B9) was below 4%. The B subgenotypes shared six common specific amino acid sites in the S region.

CONCLUSIONS

The B3, B5, B7, B8 and B9 subgenotypes can be clustered into quasi-sub-genotype B3 and the open reading frame of HBV has a start codon preference; however, whether a mutation in the start codon in the pre-S2 region has an impact on survival and replication of HBV remains to be determined.

Hepatitis B virus (HBV) variants fluctuate in paired plasma and peripheral blood mononuclear cells among patient cohorts during different chronic hepatitis B (CHB) disease phases

Hepatitis B virus is classically considered a hepatotropic virus but also infects peripheral blood mononuclear cells. Chronic hepatitis B has different disease phases modulated by host immunity. We compared HBV variability, drug resistance and immune escape mutations in the overlapping HBV polymerase/surface gene in plasma and peripheral blood mononuclear cells in different disease phases. Plasma and peripheral blood mononuclear cells were isolated from 22 treatment naïve patient cohorts (five inactive, six immune-active, nine HBeAg negative and two immune-tolerant). HBV was genotyped via line probe assay, hepatitis B surface antigen titres were determined by an in-house immunoassay, and HBV DNA was quantified by kinetic PCR. The HBV polymerase/surface region, including full genome in some, was PCR-amplified and cloned, and ~20 clones/sample were sequenced. The sequences were subjected to various mutational and phylogenetic analyses. Clonal sequencing showed that only three of 22 patients had identical HBV genotype profiles in both sites. In immune-active chronic hepatitis B, viral diversity in plasma was higher compared with peripheral blood mononuclear cells. Mutations at residues, in a minority of clones, associated with drug resistance, and/or immune escape were found in both compartments but were more common in plasma. Immune escape mutations were more often observed in the peripheral blood mononuclear cells of immune-active CHB carriers, compared with other disease phases. During all CHB disease phases, differences exist between HBV variants found in peripheral blood mononuclear cells and plasma. Moreover, these data indicate that HBV evolution occurs in a compartment and disease phase-specific fashion.

Virological characteristics of occult hepatitis B virus in a North American cohort of human immunodeficiency virus type 1-positive patients on dual active anti-HBV/HIV therapy

BACKGROUND

Occult hepatitis B virus infection (OBI) is defined as low-level HBV DNA presence in serum, liver and/or peripheral blood mononuclear cells (PBMC) in individuals that lack serum hepatitis B virus surface antigen (HBsAg). HIV+ patients with OBI may be at risk for HBV reactivation, and often receive dual active anti-HBV/HIV therapy, such as lamivudine (LMV).

OBJECTIVES

To determine the presence of OBI in a North American cohort of HIV-1-positive patients.

STUDY DESIGN/METHODS

45 HIV-1-positive, serum HBsAg-negative patients, reactive for antibodies to HBV core antigen (anti-HBc), were tested for HBV DNA in plasma and for HBV DNA and covalently closed circular DNA (cccDNA) in PBMC. Ten patients were re-tested after ∼5-10 years, including genotyping and clonal sequence analysis of the HBV polymerase (P) gene and overlapping HBV surface (S) gene from 8 PBMC samples.

RESULTS

Overall, 42% (19/45) tested HBV DNA positive, especially in PBMC (18/45), including 3/18 that were reactive for HBV cccDNA, compared to 17% (8/45) that were HBV DNA reactive in plasma. In 8 patients on LMV, sequence analysis in PBMC showed that all were HBV genotype C or D. Several carried HBV P region variants at residues associated with anti-HBV drug resistance and overlapping S gene region within the major HBsAg "a determinant".

CONCLUSION

OBI is common in HIV-positive, anti-HBc reactive patients on anti-HBV/HIV therapy, particularly in PBMC. HBV sequence analysis revealed that all had HBV genotype C or D and often had P/overlapping S gene variants possibly associated with dual-active anti-HIV/HBV therapy.

Molecular epidemiology and genetic diversity of hepatitis B virus in Mar del Plata city, Argentina

The aim of this work was to describe the current molecular epidemiology and genetic diversity of HBV in Mar del Plata, an important Argentinean touristic city. The phylogenetic analysis of 29 HBV DNA positive serum samples showed that F1b was the predominant subgenotype (sgt, 62.1%), followed by sgt A2 (13.8%) and sgt F4, gt D and gt G (6.9% each). Among anti-HBc IgM positive samples, 75.0% were sgt F1b, followed by sgt F4 (12.5%), sgt A2 (6.25%) and sgt D (6.25%). Three recombinant full length genomes were found: two G/F1b (some of the first gt G detected in Argentina) and one F4/D2. The circulation of clinical important mutations in the city was described. Mutations at the HBsAg were detected in 34.5% of the analyzed samples, associated with laboratory diagnosis and antiviral treatment failures, immune escape and hepatocellular carcinoma. Most of the samples presented wild type BCP/PC sequences. Coalescence analysis for the most prevalent sgt F1b estimated that the diversification mainly occured during mid '90s and the tMRCA was estimated in 1987. Finally, the high presence of the autochthonous sgt F1b, associated with the anti-HBc IgM positive infection and its present-day diversification process, shows the strong impact of internal human migratory movements into the current population of Mar del Plata.

Hepatitis B virus subgenotyping: history, effects of recombination, misclassifications, and corrections

Hepatitis B virus (HBV) has evolved into phylogenetically separable genotypes and subgenotypes. Accurately assigning the subgenotype for an HBV strain is of clinical and epidemiological significance. In this paper, we review the recommendations currently employed for HBV subgenotyping, the history of HBV subgenotyping, the effects of recombination on HBV subgenotyping, misclassifications in HBV subgenotyping, and suggestions are made to correct the misclassifications. Finally, proposals are made to guide future HBV subgenotyping.

New HBV subgenotype D9, a novel D/C recombinant, identified in patients with chronic HBeAg-negative infection in Eastern India

Genome diversity is a hallmark of hepatitis B virus (HBV), which allowed its classification into 10 genotypes (A-J) and numerous subgenotypes. Among them, Genotype D is currently segregated into eight subgenotypes (D1-D8). Here, we report the identification and characterization of a novel subgenotype within genotype D of HBV from chronic hepatitis B e antigen (HBeAg)-negative patients of Eastern India. Phylogenetic tree analysis based on complete genome sequences revealed that six of 39 HBV/D isolates formed a distinct cluster supported by high bootstrap value and had nucleotide divergence >4% relative to the known D subgenotypes (D1-D8), justifying their assignment into a new subgenotype (D9). By comparing the amino acid sequences of the four ORFs of HBV/D9 with D1-D8, 36 specific residues, including a unique one (E(112) in the core region), were identified that could be considered as a signature of D9. Further analysis by Simplot, BootScan and jpHMM demonstrated that D9 resulted from a discrete recombination with genotype C over the precore-core region. This type of recombination has not been described previously as all C/D recombinants reported so far possessed genotype C backbones with mosaic fragments derived from HBV/D. Interestingly, compared to other subgenotypes of HBV/D, D9 isolates had a higher frequency of mutations (A1762T and G1764A) in the basal core promoter region that had been implicated in the development of hepatocellular carcinoma. Further investigations are needed to determine the overall prevalence and clinical significance of these newly characterized D9 strains and to assess the impact of inter-genotypic recombination on viral properties.

Low prevalence of hepatitis B virus pre-S deletion mutation in Indonesia

The molecular epidemiological study of hepatitis B virus (HBV) in Indonesia is still limited. This study was aimed to identify the prevalence of HBV pre-S deletion/insertion mutations, and to assess the association of pre-S deletion mutation with liver disease progression in Indonesia. Pre-S mutations were identified by direct sequencing. Of the 265 subjects, 32 samples (12.1%) harbored pre-S deletion/insertion mutations. The prevalence of those pre-S mutations was 2.7% (2/75), 12.9% (8/62), 16.7% (11/66), and 17.7% (11/62) in asymptomatic carrier, chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma groups, respectively. Statistical analysis showed significant difference among them (P = 0.024). In HBV genotype B (HBV/B), pre-S1, pre-S1/S2, and pre-S2 deletion mutations were detected respectively in 3 (17.6%), 4 (23.5%), and 9 (52.9%) of 17 samples. On the other hand, in HBV/C, 12 of 15 samples (80.0%) showed a pre-S2 deletion mutation, and only 2 samples (13.3%) demonstrated a pre-S1/S2 deletion mutation. These results suggest that in HBV/B deletion mutation tends to occur in pre-S1 or pre-S1/S2 region, while in HBV/C the deletion mutation usually occurs in the pre-S2 region. Analysis of complete genome of four viruses confirmed that 3 isolates were classified into HBV/B3, and 1 isolate was HBV/C1. However, SimPlot and BootScan analyses showed that isolate 08.10.002 was an intragenotypic recombinant between HBV/B3 and HBV/B4. As conclusion, the prevalence of HBV pre-S mutations was relatively low in Indonesian patients compared to those from Taiwan, Japan, and other Asian countries. There was a weak association between pre-S deletion mutation and progressive liver disease.

Differential pattern of pre-S mutations/deletions and its association with hepatitis B virus genotypes in Eastern India

The presence of three different HBV genotypes (A, C and D) in Eastern India provided us a unique opportunity to study HBV pre-S mutants in these genotypes and subtypes among the same ethnic population. Furthermore, we also aimed to investigate the association of the HBV pre-S mutation with clinical outcome. Pre-S1-S2 and S gene was amplified and sequenced from 86 HBsAg positive study subjects with varying clinical manifestation. The genetic variability in the pre-S region (mutations) was studied with respect to different HBV genotypes, subtypes and different clinical categories. Six different types of HBV pre-S mutations were detected in 25 cases (29.07%), among which pre-S2 start codon mutation (28.0%) and pre-S2 deletion (24.0%) were most common. Pre-S mutation was highest in HBV/C (7/18; 38.89%) followed by HBV/A (9/27; 33.33%) and HBV/D (9/40; 22.50%). Pre-S1 deletion is common in HBV/D, whereas pre-S2 start codon mutation and pre-S2 deletions are frequent among HBV/A and HBV/C, respectively. Interestingly, in HBV/A and HBV/C the tendency of mutation/deletion increases from pre-S1 to pre-S2 region while in HBV/D the opposite tendency was observed. A significantly higher association of pre-S mutation (p=0.013) and pre-S2 deletion/ablation (p=0.016) was found among the HBeAg negative cases. Pre-S1 deletion and pre-S2 deletion were common among the ASC and CLD cases respectively, while pre-S2 start codon mutation was significantly associated with cirrhosis (p<0.05). The study underscores the association of types of pre-S mutations with particular HBV genotype and clinical outcome in the study population.

Identification of four novel subgenotypes (C13-C16) and two inter-genotypic recombinants (C12/G and C13/B3) of hepatitis B virus in Papua province, Indonesia

Four novel subgenotypes (C6, C11, C12, and D6) of hepatitis B virus (HBV) were identified in Papua, a multiethnic province of Indonesia. To characterize the HBV strains in Papua, serum samples collected from 515 indigenous inhabitants (mean age: 26.6±9.6 years) in a previously unexamined area, Nabire, located in northern Papua, were used in the present study. Among 46 samples whose 1.6-kilobase (kb) HBV DNA sequence was amplified, 38 (83%) were typeable into known subgenotypes [B3 (n=4), C1 (n=2), C5, (n=1), C6 (n=5), C12 (n=13), and D6 (n=13)]. An analysis of the full-length sequence of the eight remaining HBV/C isolates whose sequence was either unclassifiable or uncertain within the 1.6-kb sequence showed no significant evidence of recombination in six isolates, and inter-genotypic recombination in two isolates (NAB20 and NAB46). By pairwise comparisons and a maximum-likelihood phylogenetic analysis, six non-recombinant isolates were considered significantly remote from known HBV/C isolates of subgenotypes C1-C12, and were classifiable into four novel subgenotypes (tentatively designated C13-C16). NAB20 and NAB46 were hybrids of C13/B3 and C12/G, respectively, displaying recombination breakpoints in the 5'-terminus of the P gene. Notably, the distribution of presumably indigenous subgenotypes C11-C16 was associated with particular language speakers in Papua.

Geographical and ethnic distribution of the HBV C/D recombinant on the Qinghai-Tibet Plateau

Two forms of hepatitis B virus (HBV) C/D recombinant have been identified in western China, but little is known about their geographical and ethnic distributions, and particularly the clinical significance and specific mutations in the pre-core region. To address these questions, a total of 624 chronic HBV carriers from four ethnic populations representing five provinces in western China were enrolled in this study. Genotypes were firstly determined by restriction fragment length polymorphism, and then confirmed by full or partial genome nucleotide sequencing. The distribution of HBV genotypes was as follows: HBV/B: 40 (6.4%); HBV/C: 221 (35.4%); HBV/D: 39 (6.3%); HBV/CD: 324 (51.9%). In the 324 HBV C/D recombinant infections, 244 (75.3%) were infected with the “CD1” and 80 (24.7%) were infected with the “CD2.” The distribution of HBV genotypes exhibited distinct patterns in different regions and ethnic populations. Geographically, the C/D recombinant was the most prevalent HBV strain on the Qinghai-Tibet Plateau. Ethnically, the C/D recombinant had a higher prevalence in Tibetan patients than in other populations. Clinically, patients with HBV/CD1 showed significantly lower levels of serum total bilirubin than patients with HBV/C2. The prevalence of HBeAg was comparable between patients with HBV/CD1 and HBV/C2 (63.3% vs 50.0%, P = 0.118) whether patients were taken together or stratified by age into three groups (65.6% vs 58.8% in <30 years, P = 0.758; 61.9% vs 48.0% in 30–50 years, P = 0.244; 64.3% vs 33.3%, P = 0.336). Virologically HBV/CD1 had a significantly lower frequency of G1896A than HBV/C2. In conclusion, the HBV C/D recombinant is restricted to the Qinghai-Tibet Plateau in western China and is found predominantly in Tibetans. The predominance of the premature pre-core stop mutation G1896A in patients with the HBV C/D recombinant may account for the higher prevalence of HBeAg in these patients.

Molecular epidemiological study of hepatitis B virus among migrant workers from Cambodia, Laos, and Myanmar to Thailand

Although hepatitis B virus (HBV) infection is endemic in Southeast Asia, molecular epidemiological data on HBV circulating in some countries are limited. The aims of this study were to evaluate the seroprevalence of HBV and its genetic variability among migrant workers from Cambodia, Laos, and Myanmar in Thailand. Sera collected from 1,119 Cambodian, 787 Laotian, and 1,103 Myanmarese workers were tested for HBsAg. HBV DNA was amplified and the pre-S/S region was sequenced for genotyping and genetic mutation analysis. HBsAg was detected in 282 (9.4%). The prevalence of HBsAg among migrant workers from Cambodia, Laos, and Myanmar was 10.8%, 6.9%, and 9.7%, respectively. Of 224 subjects positive for HBV DNA, 86% were classified as genotype C (99% were sub-genotype C1) and 11.6% were genotype B (30.8%, 34.6%, and 30.8% were sub-genotypes B2, B3, and B4, respectively). Various point mutations in the "a" determinant region were detected in approximately 18% of these samples, of which Ile126Ser/Asn was the most frequent variant. Sequencing analysis showed that 19.1% of samples had pre-S mutations, with pre-S2 deletion as the most common mutant (7.7%) followed by pre-S2 start codon mutation (3.8%) and both pre-S2 deletion and start codon mutation (3.3%). High prevalence of HBV infection (approximately 7-11%) was found among migrant workers from Cambodia, Laos, and Myanmar, which may reflect the current seroprevalence in their respective countries. The data also demonstrated that HBV sub-genotype C1 was the predominant strain and various mutations of HBV occurring naturally were not uncommon among these populations.

Clinical relevance and public health significance of hepatitis B virus genomic variations

Ten hepatitis B virus (HBV) genotypes (A-J) and 34 HBV subgenotypes have been identified so far. HBV genotypes and subgenotypes have distinct geographical distributions, and have been shown to differ with regard to clinical outcome, prognosis, and response to interferon treatment. Infection with subgenotype A2 is frequently associated with high viral load, resulting in acute infection via horizontal transmission. Genotypes A and B are more sensitive to interferon treatment than genotypes D and C, respectively. Genotype B is more frequent in acute hepatitis than genotype C, whereas genotype C (C2) is more frequently associated with an increased risk of hepatocellular carcinoma (HCC), mostly cirrhotic, as compared with genotype B (B2). Genotype mixture is associated with high viral load and worse outcome of HBV infection. HBV mutations in the S genes, especially amino acids substitution at position 145 (G145R), are associated with immune escape, whereas mutations in the PreS or S genes which impair HBsAg secretion could present a risk to blood safety. HBV variants harboring mutations in the viral polymerase gene that confer resistance to nucleoside analogs may be selected during antiviral therapy. Different genotypes have distinct mutation patterns in the PreS and EnhII/BCP/Precore regions. PreS deletions, C1653T, T1753V, and A1762T/G1764A are associated with an increased risk of HCC. HCC-associated HBV mutants may not transmit via mother-to-child transmission, and are likely generated during HBV-induced pathogenesis. Examination of HBV mutations alone or in combination and host genetic susceptibility will be helpful in classifying the HBV-infected subjects who will develop HCC and need active anti-viral treatments.

Clinical relevance and public health significance of hepatitis B virus genomic variations

Ten hepatitis B virus (HBV) genotypes (A-J) and 34 HBV subgenotypes have been identified so far. HBV genotypes and subgenotypes have distinct geographical distributions, and have been shown to differ with regard to clinical outcome, prognosis, and response to interferon treatment. Infection with subgenotype A2 is frequently associated with high viral load, resulting in acute infection via horizontal transmission. Genotypes A and B are more sensitive to interferon treatment than genotypes D and C, respectively. Genotype B is more frequent in acute hepatitis than genotype C, whereas genotype C (C2) is more frequently associated with an increased risk of hepatocellular carcinoma (HCC), mostly cirrhotic, as compared with genotype B (B2). Genotype mixture is associated with high viral load and worse outcome of HBV infection. HBV mutations in the S genes, especially amino acids substitution at position 145 (G145R), are associated with immune escape, whereas mutations in the PreS or S genes which impair HBsAg secretion could present a risk to blood safety. HBV variants harboring mutations in the viral polymerase gene that confer resistance to nucleoside analogs may be selected during antiviral therapy. Different genotypes have distinct mutation patterns in the PreS and EnhII/BCP/Precore regions. PreS deletions, C1653T, T1753V, and A1762T/G1764A are associated with an increased risk of HCC. HCC-associated HBV mutants may not transmit via mother-to-child transmission, and are likely generated during HBV-induced pathogenesis. Examination of HBV mutations alone or in combination and host genetic susceptibility will be helpful in classifying the HBV-infected subjects who will develop HCC and need active anti-viral treatments.

Complete genome sequence and phylogenetic relatedness of hepatitis B virus isolates in Papua, Indonesia

Each hepatitis B virus (HBV) genotype and subgenotype is associated with a particular geographic distribution, ethnicity, and anthropological history. Our previous study showed the novel HBV subgenotypes C6 (HBV/C6) and D6 (HBV/D6), based on the S gene sequences of isolates in Papua, Indonesia. The present study investigated the complete genome sequence of 22 strains from Papua and subjected them to molecular evolutionary analysis. A phylogenetic analysis revealed that 9 out of 22 strains were classified as HBV/C6, 3 strains as HBV/D6, and 9 strains as HBV/B3. A particular strain positioned between HBV/B3 and HBV/B5 remained unclassifiable into any known subgenotypes. This strain showed high homology with HBV/C5 from the Philippines in the core region and was thought to have undergone genetic recombination with HBV/C5. Further studies are needed to determine whether this strain belongs to a new subgenotype of HBV/B. Based on the amino acid alignment, HBV/C6 has subgenotype specific variations (G18V and V47M) in the S region. HBV/C6 strains were more closely related in terms of evolutionary distance to strains from the east Asia and Pacific regions than those found in southeast Asia. HBV/D6 strains were most closely related to strains from the Western countries (HBV/D3) rather than those from Asia and Papua New Guinea. In conclusion, we have confirmed by complete sequence analysis that two novel HBV subgenotypes, HBV/C6 and HBV/D6, are prevalent in Papua, Indonesia.

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.