Mutations in the major hydrophilic region (MHR) of hepatitis B virus genotype C in North China

Frequency of HBsAg variants in occult hepatitis B virus infected patients and detection by ARCHITECT HBsAg quantitative

Objective

To analyze the amino acid substitution caused by mutations in the major hydrophilic region (MHR) of the S-region genes in the serum samples of occult hepatitis B virus infection (OBI), and to explore the reasons for the missed detection of HBsAg.

Method

The full-length gene of the S-region in hepatitis B virus(HBV) in the chronic hepatitis B virus(CHB)(10 samples) and OBI groups(42 samples) was amplified using a lab-developed, two-round PCR amplification technology. The PCR amplification products were sequenced/clone sequenced, and the nucleotide sequences of the S-region gene in HBV were compared to the respective genotype consensus sequence.

Results

Only 20 of the 42 samples in the OBI group had the S-region genes successfully amplified, with the lowest HBV DNA load of 20.1IU/ml. As S-region genes in HBV, 68 cloned strains were sequenced. In the OBI and CHB groups MHR region, with a mutation rate of 3.21% (155/4828) and 0.70% (5/710). The genetic mutation rate was significantly higher in the OBI group than in the CHB group (P<0.05). The common mutation types in the MHR region were: I126T, L162R, K122E, C124R, and C147Y.Mutations at s122, s126, and s162 were associated with subgenotypes, most of which being C genotypes. The high-frequency mutation sites L162R and K122E found in this study have not been reported in previous literature.

Conclusion

The results of this study confirmed that MHR mutations can cause the missed detection of HBsAg, giving rise to OBI.

Low Risk of Occult Hepatitis B Infection among Vietnamese Blood Donors

Occult hepatitis B infection (OBI) is characterized by the presence of low levels of hepatitis B virus (HBV) DNA and undetectable HBsAg in the blood. The prevalence of OBI in blood donors in Asia ranges from 0.013% (China) to 10.9% (Laos), with no data available from Vietnam so far. We aimed to investigate the prevalence of OBI among Vietnamese blood donors. A total of 623 (114 women and 509 men) HBsAg-negative blood donors were screened for anti-HBc and anti-HBs by ELISA assays. In addition, DNA from sera was isolated and nested PCR was performed for the HBV surface gene (S); a fragment of the S gene was then sequenced in positive samples. The results revealed that 39% (n = 242) of blood donors were positive for anti-HBc, and 70% (n = 434) were positive for anti-HBs, with 36% (n = 223) being positive for both anti-HBc and anti-HBs. In addition, 3% of blood donors (n = 19) were positive for anti-HBc only, and 34% (n = 211) had only anti-HBs as serological marker. A total of 27% (n = 170) were seronegative for any marker. Two of the blood donors (0.3%) were OBI-positive and sequencing revealed that HBV sequences belonged to HBV genotype B, which is the predominant genotype in Vietnam.

Analysis of S gene characteristic sequences and changes in properties of protein expression in HBV ASCs with low-level HBsAg

Objective

We detected the serum HBsAg immune complex (HBsAg-CIC) and sequenced the HBV S gene in these patients to reveal the association between sustained low-level expression of HBsAg and mutated S gene sequence characteristics, protein function changes, and HBsAg immune complex formation.

Methods

A total of 204 samples were collected and divided into high-level (n = 60, HBsAg level >10 IU/ml) and low-level (n = 144, HBsAg level ≤ 10 IU/ml) HBsAg groups. The clinical and epidemiological data of the two groups were statistically compared. According to different serological patterns and genotypes, the HBsAg-CIC results of the high-level and low-level HBsAg groups were divided into different subgroups, and then the HBsAg-CIC positive rates among different subgroups were compared. We sequenced the S gene of HBV from the two groups and identified the relevant mutations in the MHR of the S gene. In addition, we compared the changes in HBsAg protein properties and functions after hot spot mutation in the MHR of the S gene.

Results

Comparing the positive rates of HBsAg-CIC under different serological patterns and genotypes in the two groups, the HBsAg-CIC positive rate was higher in the low-level HBsAg group. Moreover, there was weak correlation between HBsAg-CIC and HBsAg or HBV DNA in both groups (r = 0.32, 0.27, 0.41, 0.48; P < 0.05). Sequencing of S gene in the two groups, showed that the hot-spot mutations were T126A, M133L/T/S, and F134L/T/I in MHR of S gene of genotype B, and hot-spot mutations were Q101R and I126S/T in MHR of S gene of genotype C. Additionally, the positive rate of MHR mutation in the S gene from HBsAg-CIC positive patients was higher in the low-level HBsAg group.

Conclusion

The host immune process of clearing HBV seems to have multiple site mutations in MHR, which changes the physicochemical properties and functions of HBsAg and intensifies the formation of HBsAg-CIC, thus avoiding the effective recognition of HBsAg by the host and resulting in immune tolerance between the host and HBV, which may be one of the formation mechanisms of sustained low-level expression of HBsAg in the serum of HBV-infected persons.

rt269I Type of Hepatitis B Virus (HBV) Polymerase versus rt269L Is More Prone to Mutations within HBV Genome in Chronic Patients Infected with Genotype C2: Evidence from Analysis of Full HBV Genotype C2 Genome

Recently, it has been reported that the rt269I type of hepatitis B virus (HBV) polymerase (Pol) versus the rt269L type is more significantly related to lower viral replication and HBeAg negative infections in chronic hepatitis B (CHB) patients of genotype C2. In this study, we compared mutation rates within HBV genomes between rt269L and rt269I using a total of 234 HBV genotype C2 full genome sequences randomly selected from the HBV database (115 of rt269L and 119 of rt269I type). When we applied the Benjamini and Hochberg procedure for multiple comparisons, two parameters, dN and d, at the amino acids level in the Pol region were significantly higher in the rt269I type than in the rt269L type. Although it could not reach statistical significance from the Benjamini and Hochberg procedure, nonsynonymous (NS) mutations in the major hydrophilic region (MHR) or “a” determinant in the surface antigens (HBsAg ORF) related to host immune escape or vaccine escape are more frequently generated in rt269I strains than in rt269L. We also found that there are a total of 19 signature single nucleotide polymorphisms (SNPs), of which 2 and 17 nonsynonymous mutation types were specific to rt269L and rt269I, respectively: Of these, most are HBeAg negative infections (preC-W28*, X-V5M and V131I), lowered HBV DNA or virion production (C-I97F/L, rtM204I/V) or preexisting nucleot(s)ide analog resistance (NAr) (rtN139K/H, rtM204I/V and rtI224V) or disease severity (preC-W28*, C-I97F/L, C-Q182K/*, preS2-F141L, S-L213I/S, V/L5M, T36P/S/A, V131I, rtN139K/H, rtM204I/V and rtI224V). In conclusion, our data showed that rt269I types versus rt269L types are more prone to overall genome mutations, particularly in the Pol region and in the MHR or “a” determinant in genotype C2 infections and are more prevalent in signature NS mutations related to lowered HBV DNA replication, HBsAg and HBeAg secretion and potential NAr variants and hepatocellular carcinoma (HCC), possibly via type I interferon (IFN-I)-mediated enhanced inflammation. Our data suggest that rt269L types could contribute to liver disease progression via the generation of immune escape or enhanced persistent infection in chronic patients of genotype C2.

A recombinant human immunoglobulin with coherent avidity to hepatitis B virus surface antigens of various viral genotypes and clinical mutants

The hepatitis B virus (HBV) envelope is composed of a lipid bilayer and three glycoproteins, referred to as the large (L), middle (M), and small (S) hepatitis B virus surface antigens (HBsAg). S protein constitutes the major portion of the viral envelope and an even greater proportion of subviral particles (SVP) that circulate in the blood. Recombinant S proteins are currently used as a preventive vaccine, while plasma fractions isolated from vaccinated people, referred to as hepatitis B immune globulin (HBIG), are used for short-term prophylaxis. Here, we characterized a recombinant human IgG1 type anti-S antibody named Lenvervimab regarding its binding property to a variety of cloned S antigens. Immunochemical data showed an overall consistent avidity of the antibody to S antigens of most viral genotypes distributed worldwide. Further, antibody binding was not affected by the mutations in the antigenic ‘a’ determinant found in many clinical variants, including the immune escape mutant G145R. In addition, mutations in the S gene sequence that confer drug resistance to the viral polymerase did not interfere with the antibody binding. These results support for a preventive use of the antibody against HBV infection.

Entecavir-resistant hepatitis B virus decreases surface antigenicity: A full genome and functional characterization

BACKGROUND AND AIM

Since polymerase and surface genes overlap in hepatitis B virus (HBV), an antiviral-induced mutation in the polymerase gene may alter the surface antigenicity in patients with chronic hepatitis B (CHB), but this possibility has not been clearly confirmed. This study aimed to determine the drug susceptibility and surface antigenicity of the patient-derived mutants.

PATIENTS AND METHODS

Full-length HBV genomes isolated from four entecavir-resistant CHB patients were cloned and sequenced. Around 10 clones of full-length HBV obtained from each patient were analysed and registered in the NCBI GenBank. Representative clones were further characterized by in vitro drug susceptibility and surface antigenicity assays.

RESULTS

The rtL180M + rtM204V mutations were common among all the clones analysed. Additionally, the ETV resistance mutations rtT184A/L, rtS202G and rtM250V were found among three patients. Most of the ETV-resistant mutants had amino acid alterations within the known epitopes recognized by T- and B-cells in the HBV surface and core antigens. The in vitro drug susceptibility assay showed that all tested clones were resistant to ETV treatment. However, they were all susceptible to ADV and TDF. More importantly, the rtI169T mutation in the RT domain, led to the sF161L mutation in the overlapping S gene, which decreased in surface antigenicity.

CONCLUSIONS

The ETV resistance mutations can affect the antigenicity of the HBsAg proteins due to changes in the overlapping sequence of this surface antigen. Thus, the apparent decline or disappearance of HBsAg needs to be interpreted cautiously in patients with previous or current antiviral resistance mutations.

PreS1 Mutations Alter the Large HBsAg Antigenicity of a Hepatitis B Virus Strain Isolated in Bangladesh

Mutations in the hepatitis B virus (HBV) genome can potentially lead to vaccination failure, diagnostic escape, and disease progression. However, there are no reports on viral gene expression and large hepatitis B surface antigen (HBsAg) antigenicity alterations due to mutations in HBV isolated from a Bangladeshi population. Here, we sequenced the full genome of the HBV isolated from a clinically infected patient in Bangladesh. The open reading frames (ORFs) (P, S, C, and X) of the isolated HBV strain were successfully amplified and cloned into a mammalian expression vector. The HBV isolate was identified as genotype C (sub-genotype C2), serotype adr, and evolutionarily related to strains isolated in Indonesia, Malaysia, and China. Clinically significant mutations, such as preS1 C2964A, reverse transcriptase domain I91L, and small HBsAg N3S, were identified. The viral P, S, C, and X genes were expressed in HEK-293T and HepG2 cells by transient transfection with a native subcellular distribution pattern analyzed by immunofluorescence assay. Western blotting of large HBsAg using preS1 antibody showed no staining, and preS1 ELISA showed a significant reduction in reactivity due to amino acid mutations. This mutated preS1 sequence has been identified in several Asian countries. To our knowledge, this is the first report investigating changes in large HBsAg antigenicity due to preS1 mutations.

A meta-analysis on genetic variability of RT/HBsAg overlapping region of hepatitis B virus (HBV) isolates of Bangladesh

Background and aim

Hepatitis B caused by HBV is a serious public health hazard prevalent worldwide including Bangladesh. Few scattered molecular studies of HBV have been reported in Bangladesh. This study aimed to analyze the genetic variability of RT/HBsAg overlapping region of HBV isolates of Bangladesh and determination of correlation among the genotype/serotype and HBsAg escape and/or drug-resistant mutations.

Methods

A total of 97 complete HBsAg sequences of Bangladeshi HBV isolates from 2005 to 2017 from NCBI GenBank were extracted and analyzed using several HBV bioinformatics tools such as Geno2pheno-HBV, HBV Serotyper, HIV-Grade:HBV-Tool, and CLC sequence viewer.

Results

The prevalence of genotypes A, C, and D are 18, 46 and 35% which correspond to serotype adw, adr, and ayw, respectively. The prevalence of HBsAg escape mutations is 51% and most of which (62%) are found in the genotype D followed by 32% in genotype C and 6% in genotype A. Interestingly most (24/36) of the sequences of HBsAg escape mutations contained 128 V mutant which all belongs to only serotype ayw3 (Genotype D). Prevalence of drug-resistant mutations is ~ 11%, most of which are from genotype C (63.64%) and D (36.36%). Lamivudine resistant mutations were found in ~ 11% of sequences followed by Telbivudine 10% and Adefovir 3% where Tenofovir showed susceptibility to all 97 sequences. Moreover, 7 among of 97 sequences showed both HBsAg and drugs resistant mutations and none of them are found due to the same nucleotide substitutions.

Conclusion

There is a strong correlation among the genotype/serotype and HBsAg escape and/or drug-resistant mutations. This meta-analytical review will be helpful for genotype-serotype prediction by PCR-based diagnosis and development of vaccine and/or diagnostic kits, and the treatment against HBV infection in the future.

Frequency of hepatitis B surface antigen variants (HBsAg) in hepatitis B virus genotype B and C infected East- and Southeast Asian patients: Detection by the Elecsys® HBsAg II assay

BACKGROUND

To avoid false negative results, hepatitis B surface antigen (HBsAg) assays need to detect samples with mutations in the immunodominant 'a' determinant region, which vary by ethnographic region.

OBJECTIVE

We evaluated the prevalence and type of HBsAg mutations in a hepatitis B virus (HBV)-infected East- and Southeast Asian population, and the diagnostic performance of the Elecsys^® HBsAg II Qualitative assay.

STUDY DESIGN

We analyzed 898 samples from patients with HBV infection from four sites (China [Beijing and Guangzhou], Korea and Vietnam). HBsAg mutations were detected and sequenced using highly sensitive ultra-deep sequencing and compared between the first (amino acids 124-137) and second (amino acids 139-147) loops of the 'a' determinant region using the Elecsys^® HBsAg II Qualitative assay.

RESULTS

Overall, 237 distinct amino acid mutations in the major hydrophilic region were identified; mutations were present in 660 of 898 HBV-infected patient samples (73.5%). Within the pool of 237 distinct mutations, the majority of the amino acid mutations were found in HBV genotype C (64.8%). We identified 25 previously unknown distinct mutations, mostly prevalent in genotype C-infected Korean patients (n = 18) followed by Chinese (n = 12) patients. All 898 samples were correctly identified by the Elecsys^® HBsAg II Qualitative assay.

CONCLUSIONS

We observed 237 distinct (including 25 novel) mutations, demonstrating the complexity of HBsAg variants in HBV-infected East- and Southeast Asian patients. The Elecsys^® HBsAg II Qualitative assay can reliably detect HBV-positive samples and is suitable for routine diagnostic use in East and Southeast Asia.

Characterization of the "a" determinant region of the hepatitis B virus genome in Iranian patients at different clinical phases of chronic infection

AIM

To determine the distribution of important mutations of the "a" determinant region in the HBV genome among patients in different clinical phases of HBV infection.

BACKGROUND

Variations in Hepatitis B infection not only change the outcome of the disease but also the symptoms from which the chronic HBV patients are suffering.

METHODS

We have meticulously selected a total of 40 chronic HBV patients from four different subclasses of chronic HBV clinical phases including immune tolerant (IT), immune active (IA), inactive carrier (IC) and hepatitis B e antigen (HBeAg)-negative (ENEG); 10 samples per each phase. Mutations of the "a" determinant region were identified using PCR-Direct sequencing method.

RESULTS

17 amino-acid substitutions at 12 positions inside the "a" determinant were identified in all forty samples; 3 mutations in the IT group, 6 mutations in the IA phase, 3 mutations in the IC patients and 5 mutations in the ENEG phase. Different substitutions were observed in all four clinical phases. The IA phase was the most variant group with the highest number of amino-acid substitutions.

CONCLUSION

These results did not reveal a strong pattern to distinguish different clinical phases of Chronic HBV infection, but there are some obvious differences regarding the number and position of mutations between these four clinical phases.

Molecular evolution of hepatitis B vaccine escape variants in China, during 2000-2016

Hepatitis B vaccine escape variants are the main threat to hepatitis B virus (HBV) infection in vaccination era worldwide. With 215 genotype B HBV and 313 genotype C HBV vaccine escape variants isolated from China during 2000-2016, we reported that genotype B HBV vaccine escape strains diverged in ∼1997 (95% HPD; 1987-2005), while genotype C HBV vaccine escape strains diverged in ∼1976 (95% HPD; 1955-2003). Additionally, the p-distance of genotype C HBV vaccine escape strains was 0.0291±0.0169, which was significantly higher than that in the genotype B HBV (t=131.02, p<0.05). However, genotype B HBV vaccine escape strains evolved more rapidly than genotype C HBV (2.103×10^-3 vs 1.083×10^-3 substitutions/site/year). Bayesian skyline plot analysis showed that the populations of genotype C HBV vaccine escape strains fluctuated more than those in genotype B HBV. Four sites (A5T/S, L21S, T/A126S and T/N131I/A) and 13 sites (N3S, T5A, G10Q/R/E, L21S, T47K/A/V, L98V/P, I/S126N/V/T, Q129H/R/L, T131P/I/N/A, G145A/R, L175S/F, L213I/S, V224A/G) were found to be under positive selection in genotype B and C HBV vaccine escape strains, respectively. More importantly, N3S, L21S, T47K, L98V, I/S126T and L213I mutations were detected in 1 (2.5%), 1 (2.5%), 1 (2.5%), 3 (7.5%), 1 (2.5%), 1 (2.5%) genotype C HBV infected Chinese younger with neonatal HBV vaccination, respectively. Therefore, our results should be valuable in further understanding the molecular evolution of HBV and providing new ideas for the elimination of HBV infection.

Investigation of a Novel Hepatitis B Virus Surface Antigen (HBsAg) Escape Mutant Affecting Immunogenicity

Mutation in the hepatitis B virus surface antigen (HBsAg) may affect the efficiency of diagnostic immunoassays or success of vaccinations using HBsAg. Thus, antigenicity and immunogenicity analyses of the mutated HBsAg are necessary to develop novel diagnostic tools and efficient vaccinations. Here, the in vitro antigenicity of three wild-type HBsAg open reading frames (ORFs) (adr4, W1S [subtype adr] and W3S [subtype adr]) isolated from clinically infected patients and nineteen synthesized single/double/multiple amino acid-substituted mutants were tested with commercial ELISA kits. Immunofluorescence staining of transfected cells and Western blot analysis confirmed that these ORFs were expressed at comparable levels in HEK-293 cells. W1S and adr4 were clearly detected, whereas W3S could not be detected. Using the same commercial immunoassay kit, we found that the single mutants, K120P and D123T, were marginally reactive, whereas W3S-aW1S and the double mutant, K120P/D123T, exhibited antigenicity roughly equivalent to the wild-type wako1S. On the other hand, the single mutants of W1S, P120K and T123D, significantly impaired the reactivity, while W1S-aW3S and the double mutant of W1S, P120K/T123D, resulted in a complete loss of antigenicity. In addition, ELISA revealed reduced HBs antigenicity of two mutants, W1S N146G and W1S Q129R/G145R. These commercial ELISA-based antigenic reactivities of HBsAg were also strongly correlated with the predicted Ai alterations of affected amino acids due to the specific mutation. In conclusion, this study showed for the first time that lysine (K120) and aspartate (D123) simultaneously affected HBsAg antigenicity, leading to diagnostic failure. These findings will improve diagnostic assays and vaccine development.

Mutation in the S gene a determinant of the hepatitis B virus associated with concomitant HBsAg and anti-HBs in a population in Northeastern Brazil

Mutations in the a determinant of S gene may develop co-existence of hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) in the serum of infected hepatitis B virus (HBV) individuals. Mutations in this region may change the antigenicity of HBsAg, which in turn, lead to escape of neutralizing action of anti-HBs antibodies. This study identified individuals with concomitant HBsAg and anti-HBs serological markers in individuals of Maranhão, Northeastern Brazil. Samples from a population-based study were evaluated for HBsAg, anti-HBs, and anti-HBc, and those that tested positive for simultaneous HBsAg and anti-HBs were submitted to HBV DNA quantification and S gene characterization by Sanger sequencing. Mutations were investigated in the a determinant located in major hydrophilic region (MHR) of the S gene. Among 3,984 samples analyzed, 92 (2.3%) were positive for HBsAg and three had the atypical HBsAg and anti-HBs-positive profile (3.26%). The frequency of HBsAg and anti-HBs co-existence was similar to previous studies. Only one individual harbored mutation in the S gene a determinant associated with this profile. Little is known about this phenomenon; however, studies as ours may contribute for future enlightenment of this important issue. J. Med. Virol. 89:458-462, 2017. © 2016 Wiley Periodicals, Inc.

Naturally Occurring Surface Antigen Variants of Hepatitis B Virus in Tunisian Patients

In Tunisia, the prevalence of naturally occurring surface (S) gene variants of hepatitis B virus (HBV) has not been determined. In the present study, the prevalence of these variants was examined in terms of the clinical and viral state in a series of 99 Tunisian patients with HBV infection. The S genes were amplified and directly sequenced. Genotype D was predominant (98%), 40.4% isolates belonged to subgenotypes D7 and 1 to subgenotype D2. The most common subtype was ayw2 (95.9%). In total, 60.6% of the studied strains harbored S mutations. Several novel mutation patterns were detected. Interestingly, the presence of S mutations was significantly correlated with the D7 subgenotype, low HBV DNA and advancing age (≥35 years), and tended to be higher in liver cirrhosis than in chronic infection. The global prevalence of the major hydrophilic region variants was 12.1%, with substitution S143L/T as the most frequent (4%). Only 33.9% of S substitutions produced amino acid changes in the polymerase gene. In conclusion, a high prevalence of naturally occurring HBsAg variants was observed among Tunisian HBV carriers. Natural viral variability in a geographical region and duration of infection are among the major factors associated with the occurrence of S mutations.

Localization of immunodominant epitopes within the "a" determinant of hepatitis B surface antigen using monoclonal antibodies

The common "a" determinant is the major immunodominant region of hepatitis B surface antigen (HBsAg) shared by all serotypes and genotypes of hepatitis B virus (HBV). Antibodies against this region are thought to confer protection against HBV and are essential for viral clearance. Mutations within the "a" determinant may lead to conformational changes in this region, which can affect the binding of neutralizing antibodies. There is an increasing concern about identification and control of mutant viruses which is possible by comprehensive structural investigation of the epitopes located within this region. Anti-HBs monoclonal antibodies (mAbs) against different epitopes of HBsAg are a promising tool to meet this goal. In the present study, 19 anti-HBs mAbs were employed to map epitopes localized within the "a" determinant, using a panel of recombinant mutant HBsAgs. The topology of the epitopes was analyzed by competitive enzyme-linked immunosorbent assay (ELISA). Our results indicate that all of the mAbs seem to recognize epitopes within or in the vicinity of the "a" determinant of HBsAg. Different patterns of binding with mutant forms were observed with different mAbs. Amino acid substitutions at positions 123, 126, 129, 144, and 145 dramatically reduced the reactivity of antibodies with HBsAg. The T123N mutation had the largest impact on antibody binding to HBsAg. The reactivity pattern of our panel of mAbs with mutant forms of HBsAg could have important clinical implications for immunoscreening, diagnosis of HBV infection, design of a new generation of recombinant HB vaccines, and immunoprophylaxis of HBV infection as an alternative to therapy with hepatitis B immune globulin (HBIG).

Characterization of hepatitis B virus surface antigen variability and impact on HBs antigen clearance under nucleos(t)ide analogue therapy

For hepatitis B virus (HBV)-related chronic infection under treatment by nucleos(t)ide analogues (NUCs), HBsAg clearance is the ultimate therapeutic goal but very infrequent. We investigated how HBV envelope protein variability could lead to differential HBsAg clearance on NUCs. For 12 HBV genotype D patients receiving NUCs, six resolvers (HBsAg clearance) were compared to six matched nonresolvers (HBsAg persistence). PreS/S amino acid (aa) sequences were analysed with bioinformatics to predict HBV envelope antigenicity and aa covariance. To enrich our analyses on very rare resolvers, these were compared with other HBV genotype D strains in three characterized clinical cohorts including common chronically infected patients. The sT125M+sP127T combination was observed in four nonresolvers of six, corroborated by aa covariance analysis, associated with a lower predicted antigenicity than sT125T+sP127P. Concordant features within this HBV key functional domain, at positions 125 and 127, were reported from two of the three comparative cohorts. In our hands, a lower ELISA reactivity of HBV-vaccinated mice sera was observed against the sT125M mutant. In the S gene, 56 aa changes in minor variants were detected in non-resolvers, mainly in the major hydrophilic region, vs 28 aa changes in resolvers. Molecular features in patients showing HBsAg persistence on NUCs argue in favour of a different aa pattern in the HBV S gene compared to those showing HBsAg clearance. In nonresolvers, a decrease in HBs 'a' determinant antigenicity and more frequent mutations in the S gene suggest a role for the HBV envelope characteristics in HBsAg persistence.

The prevalence of mutations in the major hydrophilic region of the surface antigen of hepatitis B virus varies with subgenotype

Mutations in the major hydrophilic region (MHR) of the surface antigen of hepatitis B virus (HBV) may result in vaccine escape, failure of immunotherapy and antiviral resistance. These mutants may be transmitted and constitute a public health threat. We aimed to determine the prevalence of MHR mutations of HBV in areas of high endemicity in Guangxi, China. HBV surface gene was analysed from 278 HBsAg-positive asymptomatic individuals recruited from Guangxi using cluster sampling. Three genotypes, B, C and I, were identified. The overall prevalence of MHR mutations is 17·6%. The prevalence of MHR mutations in genotype B (15·1%) is not significantly different from that in genotype C (16·4%). However, the prevalence in subgenotype C5 (31·1%) is significantly higher than in subgenotype C2 (13·0%) (χ2= 6·997,P< 0·05). The prevalence of escape mutations and overlapping polymerase substitutions in subgenotype C5 is significantly higher than in subgenotypes B2 and C2. In total, 7·9% of MHR mutants are escape mutations and 72·1% of MHR mutations produced amino-acid changes in the overlapping polymerase, including resistance mutations to entecavir. Our results suggest that the prevalence of MHR mutations varies with subgenotype. The prevalence of escape mutations and polymerase mutations may be associated with subgenotype.

S gene mutants occurrence among hepatitis B carriers in malaysia

BACKGROUND

The S gene region of the hepatitis B virus (HBV) codes for surface antigen (HBs Ag) and is responsible for classification of HBV strains.

OBJECTIVES

The current study aimed to identify important mutations in the S gene in Hepatitis B virus (HBV) isolated from Malaysian HBV carriers.

MATERIALS AND METHODS

Isolated HBV DNAs were subjected for PCR amplification and sequencing of HBV full genome.

RESULTS

A total of 76 HBV full genome and 17 partial genome sequences were obtained from the 93 sequenced sera samples Genotyping of the full genome sequences by HEPSEQ software revealed a distribution of 49.46%, 48.39% and 2.15% of genotypes C, B, and D, respectively; whereas phylogenetic and jumping profile Hidden Markov Model (jpHMM) analysis identified six (7.89%) recombinant B/C strains. The distribution of sub-genotypes were B2 (78.79%) and B3 (21.21%) for genotype B, sub genotype D2 (100%) for genotype D and sub genotype C1 (75.76%), C2 (15.15%), C3 (6.06%) and C5 (3.13%) for genotype C. Mutation analysis in the S gene demonstrated two significant mutations which were W182 stop codon and deletion at open reading frame (ORF) of pre-S1 with the frequency occurrence of 2.2% (2/93) and 5.4% (5/93), respectively. The two patients with W182 stop codon were both male, infected with HBV genotype C and one showed progression of liver disease to hepatocellular carcinoma (HCC).

CONCLUSIONS

Association with sex, genotype and clinical symptoms revealed that the pre-S1 ORF deletion occurred in 40% , 40%,and 20% of genotypes B,C, and D respectively, and 80% of the female population, of which all but one were diagnosed with chronic hepatitis B. Additionally, several mutations were found in the BCP region with the following incidence rate; C1653 T (8.6%), A1752 G (10.8%),1762 AGG--TGA 1764 (26.9%), C1766T(2.2%),T1768 A (10.8%), C1858 T (64.5%), G1896 A (25.8%).