Association of preS/S Mutations with Occult Hepatitis B Virus (HBV) Infection in South Korea: Transmission Potential of Distinct Occult HBV Variants

The N-linked glycosylation modifications in the hepatitis B surface protein impact cellular autophagy, HBV replication, and HBV secretion

N-linked glycosylation is a pivotal post-translational modification that significantly influences various aspects of protein biology. Autophagy, a critical cellular process, is instrumental in cell survival and maintenance. The hepatitis B virus (HBV) has evolved mechanisms to manipulate this process to ensure its survival within host cells. Significantly, post-translational N-linked glycosylation in the large surface protein of HBV (LHBs) influences virion assembly, infectivity, and immune evasion. This study investigated the role of N-linked glycosylation of LHBs in autophagy, and its subsequent effects on HBV replication and secretion. LHBs plasmids were constructed by incorporating single-, double-, and triple-mutated N-linked glycosylation sites through amino acid substitutions at N4, N112, and N309. In comparison to the wild-type LHBs, N-glycan mutants, including N309Q, N4-309Q, N112-309Q, and N4-112-309Q, induced autophagy gene expression and led to autophagosome accumulation in hepatoma cells. Acridine orange staining of cells expressing LHBs mutations revealed impaired lysosomal acidification, suggesting potential blockage of autophagic flux at later stages. Furthermore, N-glycan mutants increased the mRNA expression of HBV surface antigen (HBsAg). Notably, N309Q significantly elevated HBx oncogene level. The LHBs mutants, particularly N309Q and N112-309Q, significantly enhanced HBV replication, whereas N309Q, N4-309Q, and N4-112-309Q markedly increased HBV progeny secretion. Remarkably, our findings demonstrated that autophagy is indispensable for the impact of N-linked glycosylation mutations in LHBs on HBV secretion, as evidenced by experiments with a 3-methyladenine (3-MA) inhibitor. Our study provides pioneering insights into the interplay between N-linked glycosylation mutations in LHBs, host autophagy, and the HBV life cycle. Additionally, we offer a new clue for further investigation into carcinogenesis of hepatocellular carcinoma (HCC). These findings underscore the potential of targeting either N-linked glycosylation modifications or the autophagic pathway for the development of innovative therapies against HBV and/or HCC.

Synergism in actions of HBV with aflatoxin in cancer development

Aflatoxin B1 (AFB1) is a fungal metabolite found in animal feeds and human foods. It is one of the most toxic and carcinogenic of aflatoxins and is classified as a Group 1 carcinogen. Dietary exposure to AFB1 and infection with chronic Hepatitis B Virus (HBV) make up two of the major risk factors for hepatocellular carcinoma (HCC). These two major risk factors raise the probability of synergism between the two agents. This review proposes some collaborative molecular mechanisms underlying the interaction between AFB1 and HBV in accelerating or magnifying the effects of HCC. The HBx viral protein is one of the main viral proteins of HBV and has many carcinogenic qualities that are involved with HCC. AFB1, when metabolized by CYP450, becomes AFB1-exo-8,9-epoxide (AFBO), an extremely toxic compound that can form adducts in DNA sequences and induce mutations. With possible synergisms that exist between HBV and AFB1 in mind, it is best to treat both agents simultaneously to reduce the risk by HCC.

Locked nucleic acid real-time polymerase chain reaction method identifying two polymorphisms of hepatitis B virus genotype C2 infections, rt269L and rt269I

BACKGROUND

The presence of two distinct hepatitis B virus (HBV) Pol RT polymorphisms, rt269L and rt269I, could contribute to the unique clinical or virological phenotype of HBV genotype C2. Therefore, a simple and sensitive method capable of identifying both types in chronic hepatitis B (CHB) patients infected with genotype C2 should be developed.

AIM

To develop a novel simple and sensitive locked nucleic acid (LNA)-real time-polymerase chain reaction (RT-PCR) method capable of identifying two rt269 types in CHB genotype C2 patients.

METHODS

We designed proper primer and probe sets for LNA-RT-PCR for the separation of rt269 types. Using synthesized DNAs of the wild type and variant forms, melting temperature analysis, detection sensitivity, and endpoint genotyping for LNA-RT-PCR were performed. The developed LNA-RT-PCR method was applied to a total of 94 CHB patients of genotype C2 for the identification of two rt269 polymorphisms, and these results were compared with those obtained by a direct sequencing protocol.

RESULTS

The LNA-RT-PCR method could identify two rt269L and rt269I polymorphisms of three genotypes, two rt269L types [‘L1’ (WT) and ‘L2’] and one rt269I type (‘I’) in single (63 samples, 72.4%) or mixed forms (24 samples, 27.6%) in 87 (92.6% sensitivity) of 94 samples from Korean CHB patients. When the results were compared with those obtained by the direct sequencing protocol, the LNA-RT-PCR method showed the same results in all but one of 87 positive detected samples (98.9% specificity).

CONCLUSION

The newly developed LNA-RT-PCR method could identify two rt269 polymorphisms, rt269L and rt269I, in CHB patients with genotype C2 infections. This method could be effectively used for the understanding of disease progression in genotype C2 endemic areas.

Occult Hepatitis B virus (HBV) infection and challenges for hepatitis elimination: A literature review

Occult hepatitis B infection (OBI) is characterized by the detection of hepatitis B virus (HBV) DNA in serum or liver but negativity for hepatitis B surface antigen. OBI, which is thought to be maintained by host, immunological, viral and/or epigenetic factors, is one of the most challenging clinical features in the study of viral hepatitis. Currently, there is no validated detection test for OBI. It is believed that OBI is widely distributed throughout the world, with a higher prevalence in populations at high-risk HBV, but the detailed worldwide prevalence patterns are unknown. We conducted a survey of recently published studies on OBI rates across all continents. High prevalence rates of OBI are observed in some specific groups, including patients with hepatitis C virus, human immunodeficiency virus co-infection or hepatocellular carcinoma. In 2016, the World Health Organization adopted strategies to eliminate viral hepatitis by 2030, but the difficulties in detecting and treating OBI currently challenge this goal. Subjects with OBI can transmit HBV, and episodes of reactivation can occur. Further studies to understanding the mechanisms that drive the development of OBI are needed and can contribute to efforts at eliminating viral hepatitis.

Endemic HBV among hospital in-patients in Bangladesh, including evidence of occult infection

Bangladesh is one of the top-ten most heavily burdened countries for viral hepatitis, with hepatitis B (HBV) infections responsible for the majority of cases. Recombinant and occult HBV infections (OBI) have been reported previously in the region. We investigated an adult fever cohort (n=201) recruited in Dhaka, to determine the prevalence of HBV and OBI. A target-enrichment deep sequencing pipeline was applied to samples with HBV DNA >3.0 log₁₀ IU ml⁻¹. HBV infection was present in 16/201 (8 %), among whom 3/16 (19 %) were defined as OBI (HBsAg-negative but detectable HBV DNA). Whole genome deep sequences (WGS) were obtained for four cases, identifying genotypes A, C and D. One OBI case had sufficient DNA for sequencing, revealing multiple polymorphisms in the surface gene that may contribute to the occult phenotype. We identified mutations associated with nucleos(t)ide analogue resistance in 3/4 samples sequenced, although the clinical significance in this cohort is unknown. The high prevalence of HBV in this setting illustrates the importance of opportunistic clinical screening and DNA testing of transfusion products to minimise OBI transmission. WGS can inform understanding of diverse disease phenotypes, supporting progress towards international targets for HBV elimination.

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.

Hepatitis B virus pre-S region: Clinical implications and applications

Hepatitis B virus (HBV) infection is a major threat to global public health, which can result in many acute and chronic liver diseases. HBV, a member of the family Hepadnaviridae, is a small enveloped DNA virus containing a circular genome of 3.2 kb. Located upstream of the S-open-reading frame of the HBV genome is the pre-S region, which is vital to the viral life cycle. The pre-S region has high variability and many mutations in the pre-S region are associated with several liver diseases, such as fulminant hepatitis (FH), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). In addition, the pre-S region has been applied in the development of several pre-S-based materials and systems to prevent or treat HBV infection. In conclusion, the pre-S region plays an essential role in the occurrence, diagnosis, and treatment of HBV-related liver diseases, which may provide a novel perspective for the study of HBV infection and relevant diseases.

Occult Hepatitis B Virus Infection in Maintenance Hemodialysis Patients: Prevalence and Mutations in "a" Determinant

Background: Occult hepatitis B virus infection (OBI) is defined as undetectable serum hepatitis B surface antigen (HBsAg) with detectable HBV-DNA in the serum or liver. Patients with maintenance hemodialysis (MHD) are at a high risk of OBI. The prevalence of OBI in MHD patients in China is not well evaluated. In this study, we aim to assess the prevalence of OBI in MHD patients in Sichuan Province, Southwest of China and investigate the mutations in the "a" determinant of HBsAg. Methods: A total of 330 patients undergoing MHD at Sichuan Provincial People's Hospital were enrolled. Serum samples were collected for ELISA assay to test the serological markers of HBV infection, real-time PCR assay to identify the presence of HBV-DNA, and nested PCR plus sequencing analysis to investigate the gene mutations. Results: In a total of 330 MHD patients, we found that the prevalence of OBI was 4.2% (7/165) in the test group, 2.1% (7/330) in the overall dialysis cohort. After a follow-up study of 7 MHD patients with OBI for 2 years, 2 (isolated HBcAb+) of them were still detectable for HBV-DNA. By sequencing analysis, we revealed mutations at the "a" determinant of HBsAg, including Q129R, T131N, M133S, F134L and D144E. The Q129R and M133S mutations were first reported. Conclusions: Our study clarifies the prevalence of OBI in MHD patients in Sichuan Province(4.2% in the test group, 2.1% in the overall dialysis cohort), and demonstrate the mutations of Q129R and M133S in the "a" determinant of HBsAg for the first time.

No evidence of occult HBV infection in population born after mass vaccination

Despite access to efficient hepatitis B virus (HBV) vaccine and universal immunization schedules, HBV infection remains a global health concern. HBV infection has decreased by this program. Nevertheless, breakthrough infections occur due to generation of occult HBV infection (OBI) and surface gene mutants in the immunized population. We aimed to determine the presence of OBI in a population born after initiation of nationwide HBV vaccination in Tehran, Iran. A HBV mass vaccination schedule was launched in Iran in 1993. For this study, we enrolled 1120 cases younger than 24 years. ELISA was applied to evaluate the presence of HBsAg, anti-HBs and anti-HBc. HBV-DNA presence was determined in all HBsAg-negative cases using nested polymerase chain reaction. The prevalence of HBsAg, anti-HBc and anti-HBs was 0.1, 0.54 and 39.9% respectively. Out of 6 anti-HBc-positive individuals, 4 cases also had anti-HBs. One case revealed HBsAg co-existence and the other one showed isolated anti-HBc. HBV-DNA was not detected in HBsAg-negative specimens. A very low prevalence of HBsAg and isolated anti-HBc was observed and no occult HBV infection was detected. It seems that evasion mutants are not a potential threat for HBV universal immunization efficacy in the vaccinated population.

Tenofovir is a more suitable treatment than entecavir for chronic hepatitis B patients carrying naturally occurring rtM204I mutations

BACKGROUND

Hepatitis B virus (HBV) DNA polymerase mutations usually occur to long term use of nucleos(t)ide analogues (NAs), but they can occur spontaneously in treatment-naïve chronic hepatitis B (CHB) patients. The naturally occurring HBV DNA polymerase mutations might complicate antiviral therapy with NAs, leading to the generation of drug-resistant viral mutants and disease progression. The most common substitutions are known to be YMDD-motif mutations, but their prevalence and the influence on antiviral therapy is unclear.

AIM

To investigate prevalence of the naturally occurring rtM204I mutations in treatment-naïve CHB genotype C2 patients and their influence on antiviral therapy.

METHODS

A total of 410 treatment-naïve CHB patients infected with HBV genotype C2 strains were enrolled in this retrospective study. Among the 410 patients, 232 were treated with NAs for at least 12 mo. Significant fibrosis was defined as fibrosis-4 index > 3.25 or aspartate aminotransferase to platelet ratio index > 1.5. Complete viral response (CVR) during NAs was defined as undetectable serum HBV DNA (< 24 IU/mL). The rtM204I variants were analyzed by a newly developed locked nucleotide probe (LNA probe) based real-time PCR (LNA-RT-PCR) method.

RESULTS

The LNA-RT-PCR could discriminate rtM204I mutant-type (17 patients, 4.2%) from rtM204 wild-type (386 patients, 95.8%) in 403 of 410 patients (98.3% sensitivity). Multivariate analysis showed that naturally occurring rtM204I variants were more frequently detected in patients with significant fibrosis [odd-ratio (OR) 3.397, 95% confidence-interval (CI) 1.119-10.319, P = 0.031]. Of 232 patients receiving NAs, multivariate analysis revealed that achievement of CVR was reversely associated with naturally occurring rtM204I variants prior to NAs treatment (OR 0.014, 95%CI 0.002-0.096, P < 0.001). Almost patients receiving tenofovir achieved CVR at 12 mo of tenofovir, irrespective of pre-existence of naturally occurring rtM204I mutations (CVR rates: patients with rtM204I, 100%; patients without rtM204I, 96.6%), whereas, pre-existence of naturally-occurring rtM204I-mutations prior to NAs significantly affects CVR rates in patients receiving entecavir (at 12 mo: Patients with rtM204I, 16.7%; patients without rtM204I, 95.6%, P < 0.001).

CONCLUSION

The newly developed LNA-RT-PCR method could detect naturally occurring rtM204I mutations with high-sensitivity. Theses mutations were more frequent in patients with liver fibrosis. Tenofovir is a more suitable treatment than entecavir for CHB patients carrying the naturally occurring rtM204I mutations.

rt269I Type of Hepatitis B Virus (HBV) Leads to HBV e Antigen Negative Infections and Liver Disease Progression via Mitochondrial Stress Mediated Type I Interferon Production in Chronic Patients With Genotype C Infections

Hepatitis B virus infection is a serious global health problem and causes life-threatening liver disease. In particular, genotype C shows high prevalence and severe liver disease compared with other genotypes. However, the underlying mechanisms regarding virological traits still remain unclear. This study investigated the clinical factors and capacity to modulate Type I interferon (IFN-I) between two HBV polymerase polymorphisms rt269L and rt269I in genotype C. This report compared clinical factors between rt269L and rt269I in 220 Korean chronic patients with genotype C infections. The prevalence of preC mutations between rt269L and rt269I was compared using this study's cohort and the GenBank database. For in vitro and in vivo experiments, transient transfection using HBV genome plasmid and HBV virion infection using HepG2-hNTCP-C4 and HepaRG systems and hydrodynamic injection of HBV genome into mice tails were conducted, respectively. This report's clinical data indicated that rt269I vs. rt269L was more significantly related to HBV e antigen (HBeAg) negative serostatus, lower levels of HBV DNA and HBsAg, and disease progression. Our epidemiological study showed HBeAg negative infections of rt269I infections were attributed to a higher frequency of preC mutations at 1896 (G to A). Our in vitro and in vivo studies also found that rt269I could lead to mitochondrial stress mediated STING dependent IFN-I production, resulting in decreasing HBV replication via the induction of heme-oxygenase-1. In addition, we also found that rt269I could lead to enhanced iNOS mediated NO production in an IFN-I dependent manner. These data demonstrated that rt269I can contribute to HBeAg negative infections and liver disease progression in chronic patients with genotype C infections via mitochondrial stress mediated IFN-I production.

Comparison of pre-S1/S2 variations of hepatitis B virus between asymptomatic carriers and cirrhotic/hepatocellular carcinoma-affected individuals

Aim of the study

Host and viral factors can influence the clinical course of chronic hepatitis B virus (HBV) infection. Mutations in pre-S1/S2 gene regions are among the most important viral factors determining the HBV infection outcome. The aim of this study was to investigate the role of pre-S1/S2 mutations in HBV infection outcome.

Material and methods

A total of 52 samples from 26 asymptomatic carriers (ASCs) and 26 liver cirrhosis/hepatocellular carcinoma (LC/HCC) patients were enrolled. The HBV DNA genome was extracted from the sera, and pre-S1/S2 regions of the samples were amplified by nested-polymerase chain reaction, prior to being subjected to sequencing, sequence investigation and phylogenetic analysis.

Results

Certain deletions were detected mostly located at the boundary of the pre-S1 and pre-S2 regions. These deletions were detected more frequently in ASC cases than in LC/HCC patients (p < 0.007). The rate of critical point mutations, including L11Q, N37S and K38R, was significantly higher in the ASC group, whereas the A49V substitution rate was significantly higher in the LC/HCC group (p < 0.05). The phylogenetic analysis indicated that all the sequences belonged to genotype D.

Conclusions

According to the results, point mutations such as L11Q, N37S, K38R and A49V, as well as certain deletions, may be associated with HBV infection outcome, among an HBV genotype D pure population.

Effectiveness of PCR primers for the detection of occult hepatitis B virus infection in Mexican patients

BACKGROUND

Occult hepatitis B infection (OBI) is defined as the presence of hepatitis B virus (HVB) DNA in the liver of HBsAg negative individuals with or without detectable viral DNA in serum. OBI is a diagnostic challenge as it is characterized by a very low viral load, intermittently detectable through time. Individuals with OBI can develop chronic hepatic disease, including liver cirrhosis and hepatocellular carcinoma. The aim of this work was to produce tools to improve OBI detection of the HVB genotypes prevalent in Mexico.

METHODS

We designed and tested primers to detect OBI in serum samples by nested and real-time PCR. Conserved sites in the viral genome were determined by alignment of the most frequent HBV genotypes in Mexico (H, G/H, F and D) and primers spanning the entire viral genome were designed for first round and nested PCR. Primers were tested in serum samples of 45 patients not co-infected with hepatitis C virus or with HIV, out of a group of 116 HBsAg (-)/anti-HBc (+) individuals. Primers were also tested in a control group with chronic HBV. Nested PCR products obtained from HBsAg (-)/anti-HBc (+) were sequenced and used to design primers for real-time PCR (SYBR Green).

RESULTS

The most effective primer pairs to detect HBV products by nested PCR targeted ORF regions: PreS2/P, S/P, X/PreC, and C; while by real-time PCR they targeted ORF regions PreS2/P, S/P, X, and C. Out of the 45 HBsAg (-)/anti-HBc (+) patients tested, the viral genome was detected in 28 (62.2%) and 34 (75.5%), with nPCR and real-time PCR respectively.

CONCLUSION

Primers designed for real-time PCR detected up to 75.5% of suspected OBI Mexican patients, with or without liver disease, which represents an improvement from previous PCR strategies.

Molecular Characterization of Near Full-Length Genomes of Hepatitis B Virus Isolated from Predominantly HIV Infected Individuals in Botswana

The World Health Organization plans to eliminate hepatitis B and C Infections by 2030. Therefore, there is a need to study and understand hepatitis B virus (HBV) epidemiology and viral evolution further, including evaluating occult (HBsAg-negative) HBV infection (OBI), given that such infections are frequently undiagnosed and rarely treated. We aimed to molecularly characterize HBV genomes from 108 individuals co-infected with human immunodeficiency virus (HIV) and chronic hepatitis B (CHB) or OBI identified from previous HIV studies conducted in Botswana from 2009 to 2012. Full-length (3.2 kb) and nearly full-length (~3 kb) genomes were amplified by nested polymerase chain reaction (PCR). Sequences from OBI participants were compared to sequences from CHB participants and GenBank references to identify OBI-unique mutations. HBV genomes from 50 (25 CHB and 25 OBI) individuals were successfully genotyped. Among OBI participants, subgenotype A1 was identified in 12 (48%), D3 in 12 (48%), and E in 1 (4%). A similar genotype distribution was observed in CHB participants. Whole HBV genome sequences from Botswana, representing OBI and CHB, were compared for the first time. There were 43 OBI-unique mutations, of which 26 were novel. Future studies using larger sample sizes and functional analysis of OBI-unique mutations are warranted.

Prevalence of occult hepatitis B in a population from the Brazilian Amazon region

In the present study, we evaluated the prevalence of occult hepatitis B (OBI) in a population from the Brazilian Amazon region, identify circulating genotypes, and mutations in the S gene. One hundred eighty-one patients with negative serology for HBsAg and anti-HBs and positive serology for anti-HBc participated in the study. Detection of viral DNA, genotyping by sequencing, and analysis of nucleotide sequences to detect possible mutations were performed. HBV DNA was detected in 14.36% of the patients. Genotyping revealed genotype A in 88.46% of HBV DNA-positive subjects, with subgenotype A1 being the most prevalent (78.26%) followed by subgenotype A2 (21.74%). Genotype F was detected in 11.54% (all of them subgenotype F2). Amino acid substitutions were observed in the amplified S gene in individuals with OBI compared to HBsAg-positive individuals (evident infection). In conclusion, the results show a high prevalence of OBI in the population studied, with a pattern of genotypes A and F that circulate in the Brazilian Amazon region. Amino acid substitutions were detected in part of the S gene in patients with OBI. Further studies on the molecular epidemiology of HBV in this region are important to identify patients considered healthy but who are potential transmitters of the disease.

Molecular characterization of hepatitis B virus in Bangladesh reveals a highly recombinant population

The natural history and treatment outcome of hepatitis B viruses (HBV) infection is largely dependent on genotype, subgenotype, and the presence or absence of virulence associated mutations. We have studied the prevalence of genotype and subgenotype as well as virulence and drug resistance associated mutations and prevalence of recombinant among HBV from Bangladesh. A prospective cross-sectional study was conducted among treatment naïve chronic HBV patients attending at Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh for HBV viral load assessment between June and August 2015. Systematical selected 50% of HBV DNA positive patients (every second patient) were enrolled. Biochemical and serological markers for HBV infection and whole genome sequencing (WGS) was performed on virus positive sample. Genotype, subgenotype, virulence, nucleos(t)ide analogue (NA) resistance (NAr) mutations, and the prevalence of recombinant isolates were determined. Among 114 HBV DNA positive patients, 57 were enrolled in the study and 53 HBV WGS were generated for downstream analysis. Overall, 38% (22/57) and 62% (35/57) of patients had acute and chronic HBV infections, respectively. The prevalence of genotypes A, C, and D was 18.9% (10/53), 45.3% (24/53), and 35.8% (19/53), respectively. Among genotype A, C and D isolates subgenotype A1 (90%; 9/10), C1 (87.5%; 21/24) and D2 (78.9%; 15/19) predominates. The acute infection, virulence associated mutations, and viral load was higher in the genotype D isolates. Evidence of recombination was identified in 22.6% (12/53) of the HBV isolates including 20.0% (2/10), and 16.7% (4/24) and 31.6% (6/19) of genotype A, C and D isolates, respectively. The prevalence of recombination was higher in chronic HVB patients (32.2%; 10/31 versus 9.1%; 2/22); p<0.05. NAr mutations were identified in 47.2% (25/53) of the isolates including 33.9% novel mutations (18/53). HBV genotype C and D predominated in this population in Bangladesh; a comparatively high prevalence of recombinant HBV are circulating in this setting.

Genetic polymorphisms of HLA-DP and isolated anti-HBc are important subsets of occult hepatitis B infection in Indonesian blood donors: a case-control study

BACKGROUND

Occult hepatitis B infection (OBI) is defined as the presence of hepatitis B virus (HBV) DNA in the serum and/or liver in HBsAg-negative individuals. OBI is associated with the risk of viral transmission, especially in developing countries, and with progressive liver disease and reactivation in immunosuppressive patients. The objective of this study was to evaluate the relation of OBI to HLA-DP single nucleotide polymorphisms (SNPs) encoding antigen-binding sites for the immune response to HBV infection. As HLA-DP variants affect the mRNA expression of HLA-DPA1 and HLA-DPB1 in the liver, we hypothesised that high levels of HLA-DPA1 and HLA-DPB1 expression favour OBI development.

METHODS

The study enrolled 456 Indonesian healthy blood donors (HBsAg negative). OBI was defined as the presence of HBV-DNA in at least two of four open reading frames (ORFs) of the HBV genome detected by nested PCR. SNPs in HLA-DPA1 (rs3077) and HLA-DPB1 (rs3135021, rs9277535, and rs2281388) were genotyped using real-time Taqman® genotyping assays.

RESULTS

Of 122 samples positive for anti-HBs and/or anti-HBc, 17 were determined as OBI. The minor allele in rs3077 was significantly correlated with OBI [odds ratio (OR) = 3.87, 95% confidence interval (CI) = 1.58-9.49, p = 0.0015]. The prevalence of the minor allele (T) was significantly higher in subjects with OBI than in those without (59% and 33%, respectively). The combination of haplotype markers (TGA for rs3077-rs3135021-rs9277535) was associated with increased risk of OBI (OR = 4.90, 95%CI = 1.12-21.52 p = 0.038). The prevalence of OBI was highest in the isolated anti-HBc group among the three seropositive categories: anti-HBs <500 mIU/ml, anti-HBs ≥500 mIU/ml, and isolated anti-HBc (29.41%, p = 0.014).

CONCLUSION

Genetic variants of HLA-DP and the presence of anti-HBc are important predictors of OBI in Indonesian blood donors.

TRIAL REGISTRATION

Ref: KE/FK/194/EC; registered 01 March 2013. Continuing approval Ref: KE/FK/536/EC; registered 12 May 2014.

Molecular characterization of occult hepatitis B virus infection in patients with end-stage liver disease in Colombia

Background

Hepatitis B virus (HBV) occult infection (OBI) is a risk factor to be taken into account in transfusion, hemodialysis and organ transplantation. The aim of this study was to identify and characterize at the molecular level OBI cases in patients with end-stage liver disease.

Methods

Sixty-six liver samples were obtained from patients with diagnosis of end-stage liver disease submitted to liver transplantation in Medellin (North West, Colombia). Samples obtained from patients who were negative for the surface antigen of HBV (n = 50) were tested for viral DNA detection by nested PCR for ORFs S, C, and X and confirmed by Southern-Blot. OBI cases were analyzed by sequencing the viral genome to determine the genotype and mutations; additionally, viral genome integration events were examined by the Alu-PCR technique.

Results

In five cases out of 50 patients (10%) the criteria for OBI was confirmed. HBV genotype F (subgenotypes F1 and F3), genotype A and genotype D were characterized in liver samples. Three integration events in chromosomes 5q14.1, 16p13 and 20q12 affecting Receptor-type tyrosine-protein phosphatase T, Ras Protein Specific Guanine Nucleotide Releasing Factor 2, and the zinc finger 263 genes were identified in two OBI cases. Sequence analysis of the viral genome of the 5 OBI cases showed several punctual missense and nonsense mutations affecting ORFs S, P, Core and X.

Conclusions

This is the first characterization of OBI in patients with end-stage liver disease in Colombia. The OBI cases were identified in patients with HCV infection or cryptogenic cirrhosis. The integration events (5q14.1, 16p13 and 20q12) described in this study have not been previously reported. Further studies are required to validate the role of mutations and integration events in OBI pathogenesis.

Naturally occurring mutations in the reverse transcriptase region of hepatitis B virus polymerase from treatment-naïve Korean patients infected with genotype C2

AIM

To report naturally occurring mutations in the reverse transcriptase region (RT) of hepatitis B virus (HBV) polymerase from treatment naïve Korean chronic patients infected with genotype C2.

METHODS

Here, full-length HBV reverse transcriptase RT sequences were amplified and sequenced from 131 treatment naïve Korean patients chronically infected with hepatitis B genotype C2. The patients had two distinct clinical statuses: 59 patients with chronic hepatitis (CH) and 72 patients with hepatocellular carcinoma (HCC). The deduced amino acids (AAs) at 42 previously reported potential nucleos(t)ide analog resistance (NAr) mutation positions in the RT region were analyzed.

RESULTS

Potential NAr mutations involving 24 positions were found in 79 of the 131 patients (60.3%). Notably, AA substitutions at 2 positions (rt184 and rt204) involved in primary drug resistance and at 2 positions (rt80 and rt180) that functioned as secondary/compensatory mutations were detected in 10 patients (1 CH patient and 9 HCC patients) and 7 patients (1 CH and 6 HCC patients), respectively. The overall mutation frequencies in the HCC patients (3.17%, 96/3024 mutations) were significantly higher than the frequencies in the CH patients (2.09%, 52/2478 mutations) (P = 0.003). In addition, a total of 3 NAr positions, rt80, rt139 and rt204 were found to be significantly related to HCC from treatment naïve Korean patients.

CONCLUSION

Our data showed that naturally occurring NAr mutations in South Korea might contribute to liver disease progression (particularly HCC generation) in chronic patients with genotype C2 infections.

A novel hepatitis B virus-derived cis-acting sequence that enhances expression of transgenes delivered by plasmid vectors in eukaryote cell culture systems

We tested the effectiveness of a novel 13-bp hepatitis B virus (HBV)-derived cis-acting element (CAE) (ACCTCGACAAGGC), called the DT2 CAE, in augmenting transgene expression delivered by plasmid vectors in eukaryotic cells. The addition of the DT2 CAE just upstream of the start codon of several different target proteins (luciferase, EGFP, LHB, HBsAg, and MIF) in DNA plasmid constructs enhanced their translation in a posttranscriptional manner, irrespective of cell type (cell lines or primary cells) or promoter (CMV or HBV preS1 promoters), suggesting its feasibility for enhanced protein production in eukaryotic cell systems. In conclusion, a novel HBV-derived DT2 CAE could be used effectively for enhanced protein production in eukaryotic cell culture systems.

Identification of Novel A2/C2 Inter-Genotype Recombinants of Hepatitis B Virus from a Korean Chronic Patient Co-Infected with Both Genotype A2 and C2

Nearly all cases of Hepatitis B virus (HBV) infections in South Korea have the C2 genotype. Here, we have identified a chronically infected patient who was co-infected with HBV of both the A2 and C2 genotypes by screening 135 Korean chronically infected patients using direct sequencing protocols targeting the 1032-bp polymerase reverse transcriptase (RT) region. Further polymerase chain reaction (PCR)-cloning analysis (22 clones) of the RT showed that this patient had genotype C2 (12 clones), genotype A2 (six clones) and A2/C2 inter-genotype HBV recombinants (four clones). BootScan analysis showed that three of the four recombinants have different types of recombination breakpoints in both the RT and overlapping hepatitis B surface antigen (HBsAg) region. Given the significance of HBsAg as a diagnostic or vaccination target against HBV infection, clinical implications of these identified recombinants should be studied in the future. To our knowledge, this is the first report on A2/C2 inter-genotype HBV recombinants.

The characteristics of hepatitis B surface antigen (HBsAg)-negative hepatitis B virus (HBV) infection in Chinese blood donors: a follow-up study of donors tested negative for HBsAg and reactive for simultaneous nucleic acid testing of HBV, hepatitis C virus, and human immunodeficiency virus

BACKGROUND

The real infection status of hepatitis B virus (HBV) of hepatitis B surface antigen (HBsAg)-negative yet nucleic acid test (NAT)-positive blood donors is difficult to clarify. Detailed follow-up study is needed for analyzing the infectivity of these blood donors.

STUDY DESIGN AND METHODS

Blood donors who screened negative for HBsAg and reactive for simultaneous NAT of HBV, hepatitis C virus (HCV), and human immunodeficiency virus (HIV) were included in a follow-up epidemiologic questionnaire survey and contributed follow-up samples for further testing. The follow-up samples were tested repeatedly for the serologic markers and HBV DNA. The genotypes and sequence mutations of HBV infected by 11 HBV DNA-positive donors were analyzed through the amplification and sequencing of HBV S region.

RESULTS

Of the 46 donors included in this study, 89.1% were infected with HBV (41/46), including one (2.2%) window period infection, three (6.5%) recovered infections, and 37 (80.4%) occult HBV infections (OBIs). The S region of HBV was successfully amplified and sequenced for seven donors, five infected with Genotype B (71.4%), one with Genotype C (14.3%), and one with Genotype D (14.3%). Mutations in the S region were detected in four donors (57.1%) CONCLUSIONS: This is the first detailed study with multiple follow-up testing of the HBV infection status among blood donors who were tested negative for HBsAg and reactive for simultaneous NAT of HBV, HCV, and HIV. Most of these donors were infected with HBV with very low viral load. Our findings indicate that it is important to improve the sensitivity of NAT so as to decrease the residual risk of transfusion-transmitted HBV infection.

Update on occult hepatitis B virus infection

The event of mutations in the surface antigen gene of hepatitis B virus (HBV) results in undetectable hepatitis B surface antigen with positive/negative anti-hepatitis B core (anti-HBc) antibody status in serum and this phenomenon is named occult hepatitis B infection (OBI). The presence of anti-HBc antibody in serum is an important key for OBI tracking, although about 20% of OBI cases are negative for anti-HBc antibody. The diagnosis of OBI is mainly based on polymerase chain reaction (PCR) and real-time PCR assays. However, real-time PCR is a more reliable method than PCR. OBI is a great issue for the public health problem and a challenge for the clinical entity worldwide. The persistence of OBI may lead to the development of cirrhosis and hepatocellular carcinoma. With regard to OBI complications, the screening of HBV DNA by the highly sensitive molecular means should be implemented for: (1) patients with a previous history of chronic or acute HBV infection; (2) patients co-infected with hepatitis C virus/human immunodeficiency virus; (3) patients undergoing chemotherapy or anti-CD20 therapy; (4) recipients of organ transplant; (5) blood donors; (6) organ transplant donors; (7) thalassemia and hemophilia patients; (8) health care workers; (9) patients with liver related disease (cryptogenic); (10) hemodialysis patients; (11) patients undergoing lamivudine or interferon therapy; and (12) children in time of HBV vaccination especially in highly endemic areas of HBV. Active HBV vaccination should be implemented for the close relatives of patients who are negative for OBI markers. Thus, the goal of this review is to evaluate the rate of OBI with a focus on status of high risk groups in different regions of the world.

X region mutations of hepatitis B virus related to clinical severity

Chronic hepatitis B virus (HBV) infection remains a major health problem, with more than 240 million people chronically infected worldwide and potentially 650000 deaths per year due to advanced liver diseases including liver cirrhosis and hepatocellular carcinoma (HCC). HBV-X protein (HBx) contributes to the biology and pathogenesis of HBV via stimulating virus replication or altering host gene expression related to HCC. The HBV X region contains only 465 bp encoding the 16.5 kDa HBx protein, which also contains several critical cis-elements such as enhancer II, the core promoter and the microRNA-binding region. Thus, mutations in this region may affect not only the HBx open reading frame but also the overlapped cis-elements. Recently, several types of HBx mutations significantly associated with clinical severity have been described, although the functional mechanism in most of these cases remains unsolved. This review article will mainly focus on the HBx mutations proven to be significantly related to clinical severity via epidemiological studies.

Characterization of Novel Hepatitis B Virus PreS/S-Gene Mutations in a Patient with Occult Hepatitis B Virus Infection

Objective

The impact of hepatitis B virus (HBV) preS/S-gene mutations on occult HBV infection (OBI) is not fully understood. This study characterized multiple novel HBV preS/S-gene mutants obtained from an OBI patient.

Methods

PreS/S-gene mutants were analyzed by clonal sequencing. Viral replication and expression were analyzed by transfecting HBV genomic recombinants into HepG2 cells.

Results

Twenty-one preS/S-gene mutants were cloned from four sequential serum samples, including 13 mutants that were not previously documented: (1) sI/T126V+sG145R; (2) preS1 nt 3014−3198 deletion; (3) preS1 nt 3046−3177 deletion; (4) preS1 nt 3046−3177 deletion+s115−116 “INGTST” insertion; (5) preS1 nt 3046−3177 deletion+s115−116 “INGTST” insertion+sG145R; (6) preS1 nt 3115−3123 deletion+sQ129N; (7) preS1 nt 3115−3123 deletion+s126−127 “RPCMNCTI” insertion; (8) s115−116 “INGTST” insertion; (9) s115−116 “INGTST” insertion+sG145R; (10) s126−127 “RPCMNCTI” insertion; (11) preS1 nt 2848−2862 deletion+preS2 initiation codon M→I; (12) s122−123 “KSTGLCK” insertion+sQ129N; and (13) preS2 initiation codon M→I+s131−133TSM→NST. The proportion of preS1 nt 3046−3177 deletion and preS2 initiation codon M→I+s131−133TSM→NST mutants increased in the viral pool with prolonged disease. The 13 novel OBI-related mutants showed a 51.2−99.9% decrease in HBsAg levels compared with that of the wild type. Additional N-glycosylation-associated mutations, sQ129N and s131−133TSM→NST, but not s126−127 “RPCMNCTI,” greatly attenuated anti-HBs binding to HBsAg. Compared with the wild type, replication and surface antigen promoter II activity of the preS1 nt 3046−3177 deletion mutant decreased by 43.3% and 97.0%, respectively.

Conclusion

PreS/S-gene mutations may play coordinated roles in the presentation of OBI and might be associated with disease progression. This has implications for HBV diagnosis and vaccine improvement.

Precore/core region mutations of hepatitis B virus related to clinical severity

Despite the availability of an effective vaccine, hepatitis B virus (HBV) infection remains a major health problem, with more than 350 million chronically infected people worldwide and over 1 million annual deaths due to cirrhosis and liver cancer. HBV mutations are primarily generated due both to a lack of proofreading capacity by HBV polymerase and to host immune pressure, which is a very important factor for predicting disease progression and therapeutic outcomes. Several types of HBV precore/core (preC/C) mutations have been described to date. The host immune response against T cells drives mutation in the preC/C region. Specifically, preC/C mutations in the MHC class II restricted region are more common than in other regions and are significantly related to hepatocellular carcinoma. Certain mutations, including preC G1896A, are also significantly related to HBeAg-negative chronic infection. This review article mainly focuses on the HBV preC/C mutations that are related to disease severity and on the HBeAg serostatus of chronically infected patients.