A complex hepatitis B virus (X/C) recombinant is common in Long An county, Guangxi and may have originated in southern China

Concealed for a Long Time on the Marches of Empires: Hepatitis B Virus Genotype I

Genotype I, the penultimate HBV genotype to date, was granted the status of a bona fide genotype only in the XXIst century after some hesitations. The reason for these hesitations was that genotype I is a complex recombinant virus formed with segments from three original genotypes, A, C, and G. It was estimated that genotype I is responsible for only an infinitesimal fraction (<1.0%) of the chronic HBV infection burden worldwide. Furthermore, most probably due to its recent discovery and rarity, the natural history of infection with genotype I is poorly known in comparison with those of genotypes B or C that predominate in their area of circulation. Overall, genotype I is a minor genotype infecting ethnic minorities. It is endemic to the Southeast Asian Massif or Eastern Zomia, a vast mountainous or hilly region of 2.5 million km2 spreading from Eastern India to China, inhabited by a little more than 100 million persons belonging primarily to ethnic minorities speaking various types of languages (Tibeto-Burman, Austroasiatic, and Tai-Kadai) who managed to escape the authority of central states during historical times. Genotype I consists of two subtypes: I1, present in China, Laos, Thailand, and Vietnam; and I2, encountered in India, Laos, and Vietnam.

Second-Generation SARS-CoV-2 Recombinants: Lessons from Other Viruses

RNA viruses have developed notable strategies to evolve and escape host immunity [...].

A novel subgenotype I3 of hepatitis B virus in Guangxi, China: a 15-year follow-up study

Genotype I of hepatitis B virus (HBV) was proposed recently following sequencing of complete HBV genomes from Vietnam and Laos. However, its long-term molecular evolution is unknown. The objectives of this study were to study the molecular evolution of this genotype from an asymptomatic HBsAg carrier from the Long An cohort over a 15-year period was studied using both NGS and clone-based sequencing. The number of complete genome sequences obtained in 2004, 2007, 2013, and 2019 are 17, 20, 19, and 10, respectively. All strains belong to subgenotype I1, except for six (five from 2007 and one from 2019) and 8 further strains from 2007 which form a cluster branching out from other subgenotype I sequences, supported by a 100% bootstrap value. Based on complete genome sequences, all of the estimated intragroup nucleotide divergence values between these strains and HBV subgenotypes I1-I2 exceed 4%. These strains are recombinants between genotype I1 and subgenotype C but the breakpoints vary. The median intrahost viral evolutionary rate in this carrier was 3.88E-4 substitutions per site per year. The Shannon entropy (Sn) ranged from 0.55 to 0.88 and the genetic diversity, D, ranged from 0.0022 to 0.0041. In conclusion, our data provide evidence of novel subgenotypes. Considering that the 8 strains disappeared after 2007, while one of the 6 strains appears again in 2019, we propose these 6 strains as a new subgenotype, provisionally designated HBV subgenotype I3 and the 8 strains as aberrant genotype.

Hepatitis B Virus Genotype G: The Odd Cousin of the Family

With a widespread distribution but low prevalence worldwide, the hepatitis B virus (HBV) genotype G (HBV/G) is a recently described genotype for which the origin and biology are poorly understood. Some unique features make HBV/G the most peculiar of all genotypes. In this review, we reflect on the major milestones in HBV/G research, highlighting the main aspects of its discovery, molecular epidemiology, and virological and clinical characteristics. We also illustrate common pitfalls in the routine detection, which may lead to underestimated rates of HBV/G infection. Large-scale analysis of data from dozens of articles was further performed, with the aim of gaining comprehensive insights into the epidemiological aspects of HBV/G. Finally, we point out recent findings on HBV/G origins and discuss new perspectives regarding the evolutionary history of HBV/G and the plausibility of an African geographic re-emergence of this genotype.

Excavating new facts from ancient Hepatitis B virus sequences

Recently, two independent studies discovered 15 ancient Hepatitis B virus (aHBV) sequences, of which 7 dated back to the Neolithic age (NA) and the Bronze Age (BA). In the present research, all the available aHBV sequences were collectively re-analysed with reference to extant HBV diversity to understand the role of these aHBV genotypes in evolution of extant HBV genetic diversity. Several intergenotype recombination events were documented, which corroborated well with population admixture and ancient human migration. Present analyses suggested replacement of HBV genotype associated with early Neolithic European farming cultures by the migrating steppe people, during Bronze Age Steppe migration. Additionally, detailed analyses of recombinations revealed evolution of a number of extant genotypes and suggested their possible site of origin. Through this manuscript, novel and important findings of the analyses are communicated.

A systematic genotype and subgenotype re-ranking of hepatitis B virus under a novel classification standard

Background and aim

It is commonly noticed that chaotic and inefficient subgenotyping are universally used academically and clinically, a standardized HBV genotype/subgenotype classification criterion is urgently acquired. Sequence similarity, which was commonly used for the last three decades, should be upgraded by phylogenetic analysis in genotyping of recombinant-free HBV strains.

Methods

In this study, 4,429 HBV whole-genome sequences were employed to reconstruct the phylogeny of HBV using Bayesian inference. After excluding recombinant sequences, calculating partitioned evolutionary models, excluding recombinant sequences, reconstructing phylogenetic trees, and performing a correlation analysis of genetic distances, geographical distribution and serotypes, we systematically redefined the genotypes and subgenotypes of HBV.

Results

Compared to previous taxonomy, fourteen subgenotypes (A5-A7; B5-B9; C2-C4, C7; and D6-D7) were revised in the new standard. Now the HBV is divided into ten genotypes (A-J) and 24 subgenotypes (A1-A3; B1-B5; C1-C6; D1-D6; and F1-F4).

Conclusion

Our robust genotype/subgenotype new taxonomy has objectively re-molded the current shape of HBV classification. We believe that all future hepatitis B related researches or diagnosis will be benefited under the new HBV genotyping/subgenotyping standards.

Novel subgenotype D11 of hepatitis B virus in NaPo County, Guangxi, bordering Vietnam

Hepatitis B virus has been classified into 10 genotypes and 48 subgenotypes worldwide. We found previously, through polymerase chain reaction (PCR) amplification of a sample collected in 2011, that an HBsAg carrier was infected with two genotypes (B and D) of HBV. We carried out cloning, sequencing and phylogenetic analysis of the complete genomes and, for confirmation, analysed a sample collected from the same individual in 2018. Fifteen complete sequences were obtained from each sample. The carrier was infected in 2011 by genotypes B and D and by various recombinants, but only genotype D was present in 2018. The major and minor parents of the recombinants are genotypes B and D, respectively, although the recombination breakpoints vary among them. All 23 genotype D isolates form a cluster, branching out from other subgenotype D sequences and supported by a 100 % bootstrap value. Based on complete genome sequences, almost all of the estimated intragroup nucleotide divergence values between our isolates and HBV subgenotypes D1-D10 exceed 4 %. Compared to the other subgenotypes (D1-D10), 35 unique amino acids were present in our isolates. Our data provide evidence for a novel subgenotype, provisionally designated HBV subgenotype D11.

Identification of hepatitis B virus genotype I in Thailand

The rare hepatitis B virus genotype I (HBV-I) classification includes complex A/G/C/U recombinants identified amongst the individuals from China, India, Laos, and Vietnam. Herein we report the first HBV-I specimen from Thailand, with detectable HBsAg despite a 10-amino-acid truncation. This HBV-I genome has a similar recombinant pattern to reference strains, including a C region that branches basal to references, suggesting a premodern era recombination event gave rise to HBV-I. With an average sequence divergence from other genotypes ranging from 7.66% (standard deviation [SD], 0.42%; C) to 14.27% (SD, 0.31%; H), this new genome supports the HBV-I classification as a unique genotype.

Characterization of small genomic regions of the hepatitis B virus should be performed with more caution

BACKGROUND

Hepatitis B virus is a hepatotropic DNA virus that reproduces via an RNA intermediate. It can lead to an increased risk of serious liver diseases such as hepatocellular carcinoma and is a serious threat to public health. Currently, the HBV are designated based on greater than 8% nucleotide variation along the whole genome. The recombination of HBV is very common, a large majority of which are recombinants between 2 genotypes. The current work aims to characterize a suspected recombinant involving 3 genotypes.

METHODS

Fifty-seven HBV full-genome sequences were obtained from 57 patients co-infected with HBV and HIV-1 by amplification coupled with sequencing. JpHMM and RDP4 were used to perform recombination analysis respectively. The recombination results of a suspected 3-genotypic recombinant were further confirmed by both maximum likelihood phylogenetic tree and Mrbayes tree.

RESULTS

JpHMM recombination analysis clearly indicated one 3-genotypic HBV recombinant composing of B/C/D. The genotype assignments are supported by significant posterior probabilities. The subsequent phylogenetic analysis of sub-regions derived from inferred breakpoints led to a disagreement on the assignment of D segment. Investigating the conflict, further exploration by RDP4 and phylogenies revealed that the jpHMM-derived 3-genotypic recombinant is actually a B/C genotypic recombinant with C fragment spanning 1899 to 2295 (jpHMM) or 1821 to 2199 (RDP4).

CONCLUSIONS

The whole analysis indicated that (i) determination of small genomic regions should be performed with more caution, (ii) combinations of various recombination detection approaches conduce to obtain impartial results, and (iii) a unified system of nomenclature of HBV genotypes is necessary.

Novel non-canonical genetic rearrangements termed "complex structural variations" in HBV genome

BACKGROUNDS AND AIMS

Chronic hepatitis B virus (HBV) infection is an important worldwide public health issue. Further knowledge on the characteristics of HBV will facilitate its eradication. Genome structural variations (SVs) are defined by its canonical form such as duplication, deletion, and insertion. However, recent studies have reported complex SVs that cannot be explained by those canonical SVs. A HBV strain (UK2) with an unusual genome structure rearrangement that was completely different from known mutations or rearrangements was previously reported. Thus, this study was conducted to confirm the rearrangement in UK2 as a novel complex SV, and to find additional HBV strains with complex SVs. Further, the contribution of complex SVs in hepadnavirus variability was investigated.

METHODS

The genome rearrangement pattern in UK2 was analyzed. Further, a search of online databases retrieved additional HBV strains which were candidates to harbor complex SVs. The architecture of each rearrangement in the candidate strains was analyzed by bioinformatical tools. In addition, alignment of woolly monkey hepatitis virus (WMHV) and HBV from human and non-human primates was performed to investigate the contribution of complex SVs to variability of hepadnavirus.

RESULTS

The rearrangement in UK2 was confirmed as a complex SV. An additional 15 HBV strains were retrieved from databases, and confirmed as harboring complex SVs. Complex combinations of deletion, insertion, and duplication characterized the novel rearrangements. The complex SVs in six strains (37.5%) were composed of deletion, insertion, and duplication. The complex SVs in another six strains (37.5%) consisted of deletion and insertion, followed by insertions and duplication in three strains (18.8%), and deletion and duplication in one strain (6.3%). In addition, unique preS1 promoter insertions, which contained the hepatocyte nuclear factor 1 binding site, were observed in seven (43.8%) of 16 strains. Further, analysis of the genetic sequences of WMHV and HBV from human and non-human primates showed that complex combinations of deletions and insertions accounted for their genetic differences.

CONCLUSIONS

Non-canonical genetic rearrangements termed complex SVs were observed in HBV. Further, complex SVs accounted for the genetic differences of WMHV and HBV from human and non-human primates.

Overview of hepatitis B viral replication and genetic variability

Chronic infection with hepatitis B virus (HBV) greatly increases the risk for liver cirrhosis and hepatocellular carcinoma (HCC). HBV isolates worldwide can be divided into ten genotypes. Moreover, the immune clearance phase selects for mutations in different parts of the viral genome. The outcome of HBV infection is shaped by the complex interplay of the mode of transmission, host genetic factors, viral genotype and adaptive mutations, as well as environmental factors. Core promoter mutations and mutations abolishing hepatitis B e antigen (HBeAg) expression have been implicated in acute liver failure, while genotypes B, C, subgenotype A1, core promoter mutations, preS deletions, C-terminal truncation of envelope proteins, and spliced pregenomic RNA are associated with HCC development. Our efforts to treat and prevent HBV infection are hampered by the emergence of drug resistant mutants and vaccine escape mutants. This paper provides an overview of the HBV life cycle, followed by review of HBV genotypes and mutants in terms of their biological properties and clinical significance.

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.

Hepatitis B virus genotypes and genome characteristics in China

AIM: To analyze the hepatitis B virus (HBV) characters in China, as well as the correlation between several HBV mutation and hepatitis symptoms.

METHODS: A total of 1148 HBV genome sequences from patients throughout China were collected via the National Center For Biotechnology Information database (information including: genotype, territory and clinical status). HBV genotypes were classified by a direct reference from the Genbank sequence annotation, phylogenetic tree and online software analysis (http://www.ncbi.nlm.nih.gov/projects/genotyping/formpage.cgi). The phylogenetic tree was constructed based on the neighbor-joining method by MEGA5.0 software. HBV sequences were grouped based on phylogenetic tree and the distance between the groups was calculated by using the computer between group mean distance methods. Seven hundred and twelve HBV sequences with clear annotation of clinical symptoms were selected to analyses the correlation of mutation and clinical symptoms. Characteristics of sequences were analyzed by using DNAStar and BioEdit software packages. The codon usage bias and RNA secondary structures analysis were performed by RNAdraw software. Recombination analysis was performed by using Simplot software.

RESULTS: In China, HBV genotype C was the predominant in Northeastern, genotype B was predominant in Central Southern areas, genotype B and C were both dominant in Southwestern areas, and the recombinant genotype C/D was predominant in Northwestern areas. C2 and B2 were identified as the two major sub-genotypes, FJ386674 might be a putative sub-genotype as B10. The basal core promoter double mutation and pre-C mutation showed various significant differences between hepatitis symptoms. In addition to ATG, many other HBV initiation codons also exist. HBV has codon usage bias; the termination codon of X, C and P open reading frames (ORF) were TAA, TAG, and TGA, respectively. The major stop codons of S-ORF were TAA (96.45%) and TGA (83.60%) in B2 and C2 subtype, respectively.

CONCLUSION: This study recapitulated the epidemiology of HBV in China, and the information might be meaningful critical for the future prevention and therapy of HBV infections.

Genotype I of hepatitis B virus was found in east Xishuangbanna, China and molecular dynamics of HBV/I

There is a dearth of data about the prevalence of hepatitis B virus (HBV) infection in Mengla, China; and no detailed analysis of the molecular evolution of genotype I in Asia. In this study, 909 serum samples from ethnic minority people in China were obtained. Serological assay and HBV S-gene amplification were carried out, and phylogenetic and evolutionary dynamics analysis of 62 HBV/I S-gene was performed. On this survey, 153 individuals were tested HBsAg-positive. Genotypes of S-gene were classified into three groups: C, B and I. Under the strict model and the relax model, the estimated evolutionary rates for HBV/I were 3.74 × 10(-4) and 6.93 × 10(-4) substitution/site/year, respectively. However, when the geographic origin was taken into account, the mean substitution rates were increased. Estimated time to most recent ancestor of genotype I varied from ~30 to ~70 years ago. The Bayesian sky plot showed a rapid spread of HBV/I at the end of 1980s. Peculiar nucleotides distributed were observed in the subgenotype I1/I2. In conclusion, higher prevalence of HBV infection was observed in Mengla county. Multifactors like timescale and spatial locations should be integrated to provide a better interpretation of the HBV/I evolutionary history in the region.

The Effect of HBV Genotype C on the Development of HCC Differs Between Wild-Type Viruses and Those With BCP Double Mutations (T(1762)A(1764))

BACKGROUND

Association of hepatitis B virus (HBV) genotype C with hepatocellular carcinoma (HCC) development remains controversial. HBV basal core promoter (BCP) double mutations (T(1762)A(1764)) are very strong confounding factors of genotypes B and C in HCC development.

OBJECTIVES

To investigate the association of HBV genotype C with HCC development after controlling for BCP double mutations.

MATERIALS AND METHODS

Four hundred and two serum samples from patients with HCC, liver cirrhosis (LC) and chronic hepatitis (CH) and also from asymptomatic HBsAg carriers were analyzed.

RESULTS

Genotypes B (31.1%), C (62.8%), and I (6.1%) were detected. With the severity of liver disease the prevalence of genotype B decreased, but genotype C increased. No trend was found for genotype I. The prevalence of BCP double mutations in genotypes C and I viruses was significantly higher than genotype B. BCP double mutations are risk factors for CH, LC and HCC. Genotype C was not identified as a particular risk factor for HCC prior to the stratification analysis but after that genotype C viruses with BCP double mutations were found to be a particular risk factor for HCC (P = 0.008, OR = 17.19 [95% CI: 2.10 - 140.41]), but those with the wild-type BCP were not. In the interaction analysis, genotype C and BCP double mutations were found to have a synergistic effect on HCC development (P < 0.0001, OR = 52.56 [95% CI: 11.49-240.52]).

CONCLUSIONS

The effect of HBV genotype C on the development of HCC differs between wild-type viruses and those with BCP double mutations, suggesting that not all individuals infected with genotype C HBV are at increased risk of HCC.

A novel complex A/C/G intergenotypic recombinant of hepatitis B virus isolated in southern China

Hepatitis B virus (HBV) genotypes and subgenotypes may vary in geographical distribution and virological features. Previous investigations, including ours, showed that HBV genotypes B and C were respectively predominant in South and North China, while genotypes A and D were infrequently detected and genotype G was not found. In this study, a novel A/C/G intergenotype was identified in patients with chronic HBV infection in Guilin, a city in southern China. Initial phylogenetic analysis based on the S gene suggested the HBV recombinant to be genotype G. However, extended genotyping based on the entire HBV genome indicated it to be an A/C/G intergenotype with a closer relation to genotype C. Breakpoint analysis using the SIMPLOT program revealed that the recombinant had a recombination with a arrangement of genotypes A, G, A and C fragments. Compared with the HBV recombinants harboring one or two genotype G fragments found in Asian countries, this Guilin recombinant was highly similar to the Vietnam (98-99%) and Long An recombinants (96-99%), but had a relatively low similarity to the Thailand one (89%). Unlike those with the typical genotype G of HBV, the patients with the Guilin recombinant were seropositive for HBeAg. Moreover, a relatively high HBV DNA viral load (>2 × 10(6) IU/ml) was detected in the patients, and the analysis of viral replication capacity showed that the Guilin recombinant strains had a competent replication capacity similar to genotypes B and C strains. These findings can aid in not only the clarification of the phylogenetic origin of the HBV recombinants with the genotype G fragment found in Asian countries, but also the understanding of the virological properties of these complicated HBV recombinants.

Hepatitis B virus candidate subgenotype I1 varies in distribution throughout Guangxi, China and may have originated in Long An county, Guangxi

Sequencing of the complete hepatitis B virus (HBV) genomes from Vietnam, China and Laos led to the identification of a complex recombinant, referred to initially as an aberrant genotype and later proposed to be a new genotype, I. However, epidemiological data regarding this new genotype are lacking. A cross-sectional study was carried out to investigate the epidemiology of HBV candidate genotype I in Guangxi, China using stratified, random cluster sampling. Four thousand five hundred thirteen subjects were recruited from five counties within Guangxi. Three genotypes, B, C, and I, were identified with a prevalence of 32.6% (114/350), 64% (224/350), and 3.4% (12/350), respectively. All the genotype I isolates belong to candidate subgenotype I1 and were found in Bing Yang (15.3%, 9/59) and Na Po (5.0%, 3/60) counties only. The prevalence of this subgenotype is significantly higher in males (5.1%, 10/195) than in females (1.3%, 2/155; X(2)  = 3.959, P < 0.05) but does not differ significantly with age. It was found in the Han (4.5%, 9/201) and Zhuang (3.1%, 3/97) ethnic populations only. There is no significant difference from other genotypes in the prevalence of HBV serological markers. Phylogeographic analysis revealed that genotype I1 likely arose in Long An county, then spread later to Bing Yang, Na Po counties and elsewhere in southeast Asia. In conclusion, the distribution of candidate genotype I within Guangxi is not even and it is highly endemic in some counties. Its prevalence is associated with gender and ethnicity. Subgenotype I1 likely originated in Long An county.

Resolving ambiguity in the phylogenetic relationship of genotypes A, B, and C of hepatitis B virus

Background

Hepatitis B virus (HBV) is an important infectious agent that causes widespread concern because billions of people are infected by at least 8 different HBV genotypes worldwide. However, reconstruction of the phylogenetic relationship between HBV genotypes is difficult. Specifically, the phylogenetic relationships among genotypes A, B, and C are not clear from previous studies because of the confounding effects of genotype recombination. In order to clarify the evolutionary relationships, a rigorous approach is required that can effectively explore genetic sequences with recombination.

Result

In the present study, phylogenetic relationship of the HBV genotypes was reconstructed using a consensus phylogeny of phylogenetic trees of HBV genome segments. Reliability of the reconstructed phylogeny was extensively evaluated in agreements of local phylogenies of genome segments.

The reconstructed phylogenetic tree revealed that HBV genotypes B and C had a closer phylogenetic relationship than genotypes A and B or A and C. Evaluations showed the consensus method was capable to reconstruct reliable phylogenetic relationship in the presence of recombinants.

Conclusion

The consensus method implemented in this study provides an alternative approach for reconstructing reliable phylogenetic relationships for viruses with possible genetic recombination. Our approach revealed the phylogenetic relationships of genotypes A, B, and C of HBV.

Hepatitis B virus with a proposed genotype I was found in Sichuan Province, China

To date, eight hepatitis B virus (HBV) genotypes, A-H, have been designated, and two additional genotypes, I and J, have also been proposed. A serological survey targeting children in difficult-to-reach vaccination areas was carried out in remote counties of Sichuan Province, China. HBV genotypes and serotypes were also determined from HBsAg-positive serum samples by direct sequencing. Phylogenetic analysis showed two strains isolated from the Yi ethnic children clustered with the proposed genotype I. The pairwise genome genetic distance was 7.5% between genotypes I and C, and ranged from 8.4% to 15.2% between genotype I and other genotypes, except genotype C. Grouping Scan analyses of the two strains revealed apparent recombination events between an unknown genotype and genotype C. Two out of four HBV strains isolated from the Yi ethnic children were confirmed to be genotype I, suggesting widespread circulation and common infection with genotype I HBV in the local Yi population. High prevalence of HBsAg and low hepatitis B vaccination coverage indicated that additional efforts are needed to control HBV infection in those areas.

A multicentre molecular analysis of hepatitis B and blood-borne virus coinfections in Viet Nam

Hepatitis B (HBV) infection is endemic in Viet Nam, with up to 8.4 million individuals estimated to be chronically infected. We describe results of a large, multicentre seroepidemiological and molecular study of the prevalence of HBV infection and blood-borne viral coinfections in Viet Nam. Individuals with varying risk factors for infection (n = 8654) were recruited from five centres; Ha Noi, Hai Phong, Da Nang, Khanh Hoa and Can Tho. A mean prevalence rate of 10.7% was observed and levels of HBsAg were significantly higher in injecting drug users (IDUs) (17.4%, n = 174/1000) and dialysis patients (14.3%, n = 82/575) than in lower-risk groups (9.4%; p<0.001). Coinfection with HIV was seen in 28% of HBV-infected IDUs (n = 49/174) and 15.2% of commercial sex workers (CSWs; n = 15/99). HCV infection was present in 89.8% of the HBV-HIV coinfected IDUs (n = 44/49) and 40% of HBV-HIV coinfected CSWs (n = 16/40). Anti-HDV was detected in 10.7% (n = 34/318) of HBsAg positive individuals. Phylogenetic analysis of HBV S gene (n = 187) showed a predominance of genotype B4 (82.6%); genotypes C1 (14.6%), B2 (2.7%) and C5 (0.5%) were also identified. The precore mutation G1896A was identified in 35% of all specimens, and was more frequently observed in genotype B (41%) than genotype C (3%; p<0.0001). In the immunodominant 'a' region of the surface gene, point mutations were identified in 31% (n = 58/187) of sequences, and 2.2% (n = 4/187) and 5.3% (n = 10/187) specimens contained the major vaccine escape mutations G145A/R and P120L/Q/S/T, respectively. 368 HBsAg positive individuals were genotyped for the IL28B SNP rs12979860 and no significant association between the IL28B SNP and clearance of HBsAg, HBV viral load or HBeAg was observed. This study confirms the high prevalence of HBV infection in Viet Nam and also highlights the significant levels of blood-borne virus coinfections, which have important implications for hepatitis-related morbidity and development of effective management strategies.

Novel evidence of HBV recombination in family cluster infections in western China

Two hepatitis B virus (HBV) C/D recombinants were isolated from western China. No direct evidence indicates that these new viruses arose as a result of recombination between genotype C and D or a result of convergence. In this study, we search for evidence of intra-individual recombination in the family cluster cases with co-circulation of genotype C, D and C/D recombinants. We studied 68 individuals from 15 families with HBV infections in 2006, identified individuals with mixed HBV genotype co-infections by restriction fragment length polymorphism and proceeded with cloning and DNA sequencing. Recombination signals were detected by RDP3 software and confirmed by split phylogenetic trees. Families with mixed HBV genotype co-infections were resampled in 2007. Three of 15 families had individuals with different HBV genotype co-infections in 2006. One individual (Y2) had a triple infection of HBV genotype C, D and C/D recombinant in 2006, but only genotype D in 2007. Further clonal analysis of this patient indicated that the C/D recombinant was not identical to previously isolated CD1 or CD2, but many novel recombinants with C2, D1 and CD1 were simultaneously found. All parental strains could recombine with each other to form new recombinant in this patient. This indicates that the detectable mixed infection and recombination have a limited time window. Also, as the recombinant nature of HBV precludes the possibility of a simple phylogenetic taxonomy, a new standard may be required for classifying HBV sequences.

The influence of HLA alleles and HBV subgenotyes on the outcomes of HBV infections in Northeast China

Hepatitis B virus (HBV) infection has a wide variety of clinical outcomes, it could be spontaneouly recovered and also could develop fulminant liver failure or cirrhosis with hepatocellular carcinoma. Human leukocyte antigen (HLA) polymorphism and HBV (sub)genotypes have been speculated to associate with the outcome of HBV infection because the data obtained from various populations who bear different HLA alleles have shown a HLA polymorphism associated outcome of HBV infection. However, as the most important viral and host genetic factors, the impact of HBV (sub)genotypes in combination with HLA polymorphism on the clinical outcomes of HBV infections remains unclear. To demonstrate the association of HLA allele polymorphism in combination with HBV subgenotypes with the outcome of HBV infection in Northeastern Han Chinese population, a total of 230 HBV-infected individuals (Infection group) were compared to 210 random selected controls (Control group) who are negative for HBV infection for their HLA alleles frequency as well as the associations with the virus infection, clearance and persistence in combination with HBV subgenotypes. Of the 230 HBV-infected subjects, 54 were acute self-limited hepatitis (ASH) with HBV subgenotype C2 (ASH-C2), 144 were chronic hepatitis (CH) with HBV subgenotype C2 and B2 (CH-C2 and CH-B2), and 32 were spontaneously recovered (SR) without subgenotype results. When two groups are compared, the results suggest that B*48, B*51 and DRB1*12 carrier may have a high risk for HBV infection, but B*51 is likely association with spontaneous recovery and DRB1*07, 12 may be implied in viral persistence. HLA-B*15, DRB1*11 and 14 associated with viral clearance in the cases of HBV-C2 infection; HLA-B*54 carriers in chronic group are more sensitive to with the infection of HBV subgenotype B2; HLA-B*07 and DRB1*13 may protect subjects from HBV infection. The data presented a link between HLA polymorphism and HBV pathogenesis and suggested potential therapeutic targets for hepatitis B.