Risk of hepatic decompensation from hepatitis B virus reactivation in hematological malignancy treatments

In this editorial,we discussed the apparent discrepancy between the findings described by Colapietro et al,in their case report and data found in the literature.Colapietro et al reported a case of hepatitis B virus(HBV)-related hepatic decompensation in a patient with chronic myeloid leukemia and a previously resolved HBV infection who was receiving Bruton’s tyrosine kinase(BTK)inhibitor therapy.First of all,we recapitulated the main aspects of the immune system involved in the response to HBV infection in order to underline the role of the innate and adaptive response,focusing our attention on the protective role of anti-HBs.We then carefully analyzed literature data on the risk of HBV reactivation(HBVr)in patients with previous HBV infection who were treated with either tyrosine kinase inhibitors or BTK inhibitors for their hematologic malignancies.Based on literature data,we suggested that several factors may contribute to the different risks of HBVr:The type of hematologic malignancy;the type of therapy(BTK inhibitors,especially second-generation,seem to be at a higher risk of HBVr than those with tyrosine kinase inhibitors);previous exposure to an anti-CD20 as first-line therapy;and ethnicity and HBV genotype.Therefore,the warning regarding HBVr in the specific setting of patients with hematologic malignancies requires further investigation.

Construction of an immune-related prognostic model to predict prognosis and immunotherapy in liver cancer patients with hepatitis B virus-infected

Background:Hepatocellular carcinoma(HCC)appears to be strongly associated with immune-related genes.However,immune-related genes are not well understood as a prognostic marker in HCC caused by the hepatitis B virus(HBV).The purpose of this study was to investigate the prognostic significance of immune-related genes in HBV-infected HCC.Methods:Gene expression data from 114 HBV-infected HCC and 50 normal tissues were integrated into The Cancer Genome Atlas.Differentially expressed immune-associated genes were analyzed to identify immune-associated differential genes associated with overall survival.Least Absolute Shrinkage and Selection Operator and multivariate Cox regressions were used to constructing immunoprognostic models.An independent prognostic factor analysis using multiple Cox regressions was also performed for HBV-infected HCCs.Immunocorrelation analysis markers and immune cell infiltration were also investigated.Results:We found 113 differentially expressed immune-associated genes.Immune-related differential genes were significantly correlated with the overall survival of HCC patients.We constructed an immune-based prognostic model using multivariate Cox regression analysis including seven immune-related genes.According to further analysis,immune-related prognostic factors may serve as independent prognostic indicators in the clinical setting.There is also evidence that the 7-gene prognostic model reflects the tumor immune microenvironment as a result of the risk score model and immune cell infiltration.Conclusions:As a result of our study,we screened immune-related genes for prognosis in HBV-infected HCC and developed a novel immune-based prognostic model.The research not only provides new prognostic biomarkers but also offers insight into the tumor immune microenvironment and lays the theoretical groundwork for immunotherapy.

Identification and Characterization of Hepatitis B Virus Immune Escape Mutants in Kenya

Hepatitis B Virus (HBV) infections affect about 400 million people globally and cause about 1.4 million deaths annually. The virus displays high levels of genetic variations/mutations, some of which are immune escape mutants. The prevalence of HBV infection in Kenya is high at about 8%. This study aimed at identifying and characterizing HBV immune escape mutants in Kenya. From 547 HBV sequences available in Kenya in NCBI, and HBVdb databases in July 2021, 120 full sequences were retrieved. The S gene sequences at position 1-225, which included the “a” determinant region of the gene were analyzed using various bioinformatics tools such as Bioedit software, and Emboss Cons. The clinical significance was flagged from the search of peer-reviewed journals. Forty-six HBV-positive blood donor samples were obtained from the Kenya National Blood Transfusion Services without personal identifiers, DNA extracted, and sequenced targeting positions 1 to 520 of S genes. Mutations were similarly identified from seventeen sequences after cleaning and analysis. Out of 120 sequences that were extracted from databases and analyzed, 79 different mutations were identified. Fifteen of them were of clinical importance with an occurrence frequency of at least 5% were obtained. The majority (64.6%, n = 51), with S207N and A194V being most dominant, could result in immune escape and reduced HBsAg detection signals while 24.1% (n = 19) could result in immune escape/reduced HBsAg detection signals and high probability of hepatocellular carcinoma. Most likely to occur on the amino acids Alanine, Lysine, Serine, Asparagine, and Valine in decreasing order. The most dominant genotype was found to be Genotype A (N = 10), while four sequences were Genotype D. In contrast to the in-silico studies, the sequences from HBV samples from blood donors did not demonstrate the presence of S207N and A194V mutations and all the genotypes were type A1. Only two (13.3%) samples showed the same mutations of sK122R and sT143S for both in-silico analysis and actual sequenced samples. This study did not identify G145R mutation which is the commonest mutation within the HBsAg immunodominant “a” determinant that is associated with immune escape. The concordance of mutations in “a” determinant region of HBsAg gene among various studies is minimal. The study identified new mutations (sA194Y, sS207, sA194S, sS207I, sP46A, sA194T, sS207I, sP46R, and sT143P) that had not been published before. Four (20%) of the mutations were clinically significant. These included sS207R, sT143S, sC76F and sK122R.

Expression of hepatitis B virus genes in early embryonic cells originated from hamster ova and human spermatozoa transfected with the complete viral genome

Aim： To detect the expression of hepatitis B virus （HBV） genes （HB S and C genes） in early embryonic cells after introducing motile human sperm carrying HBV DNA into zona-free hamster oocytes via the in vitro fertilization （IVF） technique. Methods： Human sperm-mediated HBV genes were delivered into zona-free hamster oocytes by the IVF method. Polymerase chain reaction （PCR） was used to detect HB S and pre-Core/Core （pre-C/C） coding genes both in one- and two-cell embryos. Reverse transcription-PCR （RT-PCR） analysis was used to study the expression of the two genes. Fluorescence in situ hybridization （FISH） analysis using the full-length HBV DNA as the hybridization probe was performed to confirm the integration of viral DNA in the host embryonic genome. Results： Both HB S and pre-C/C coding genes are present and transcribed in one- and two-cell embryos originated from hamster ova IVF with human spermatozoa carrying HBV DNA sequences. Conclusion： Sperm-mediated HBV genes are able to replicate and express themselves in early embryonic cells. These results provide direct evidence that HBV DNA could transmit vertically to the next generation via the male germ line.

Gene heterogeneity of hepatitis B virus isolates from patients with severe hepatitis B

BACKGROUND: The pathogenesis of severe hepatitis B remains unknown. Reports have indicated that hepatitis B virus (HBV) mutations are important factors in the pathogenesis of this disease. This study was to investigate the genetic heterogeneity of HBV strains from serum samples of patients with fulminant hepatitis B. METHODS: Full-length HBV genomes from 4 patients with severe hepatitis B were cloned and sequenced to observe mutations in every open reading-frame ( ORF). Serum samples of another 25 patients with severe hepatitis B, 30 patients with chronic hepatitis B, and 25 HBV carriers were collected for sequencing and comparison of mutations in preS2, preC and core promoter regions. RESULTS: Of 4 HBV full-length genome sequences, 3 had a G to A mutation at nucleotide A1896 in the preC region and 1 had double mutations of T1762-A1764 in the core promoter region. The 4 sequences showed mutations in the known B or T cell epitopes of the preS2 and C regions. For the other 3 groups, more mutations were seen in the preS2 region in the HBV isolates from the patients with severe hepatitis B than those from the patients with chronic hepatitis B and HBV carriers (P <0.01). There was a significant difference of mutations in the T cell epitope region of preS2 between the patients with severe hepatitis B and those with chronic hepatitis B or HBV carriers (P <0.01). In the preC and core promoter regions, the mutation frequencies of T1653 and C1753 were 48.0% and 24.0% respectively in the patients with severe hepatitis B, but none of these mutations were observed in the patients with chronic hepatitis B group or HBV carriers (P <0.01). The mutation frequency of T1762-A1764 was 76.0% in the patients with severe hepatitis B, 40.0% in the patients with chronic hepatitis B (P <0. 01) , and 16. 0% in the HBV carriers ( P < 0. 01). There was a significant difference in A1896 mutation between the patients with severe hepatitis B and the patients with chronic hepatitis B (P < 0. 05 ) or the HBV carriers (P<0.05). CONCLUSION: Our observations suggest that the accumulation and persistence of high frequency mutations or complex mutations may be associated with the development and deterioration of HBV infection.

Preliminary study on the production of transgenic mice harboring hepatitis B virus X gene

AIM To establish transgenic mice lineage xharboring hepatitis B virus X gene and to provide an efficient animal model for studying the exact role of the HBx gene in the process of hepatocarcinogenesis. METHODS The HBx transgenic mice were produced by microinjecting the construct with X gene of HBV (subtype adr) DNA fragment into fertilized eggs derived from inbred C57 BL/6 strain; transgenic mice were identified by using Nested PCR; expression and phenotype of HBx gene were analyzed in liver from transgenic mice at the age of 8 weeks by RT PCR, pathologic examination and periodic acid schiff staining (PAS), respectively. RESULTS Five hundred and fourteen fertilized eggs of C57 BL/6 mice were microinjected with recombinant retroviral DNA fragment, and 368 survival eggs injected were transferred to the oviducts of 18 pseudopregnant recipient mice, 8 of them became pregnant and gave birth to 20 F1 offspring. Of 20 offsprings, four males and two females carried the hybrid gene (HBx gene). Four male mice were determined as founder, named X1, X5, X9 and X15. These founders were back crossed to set up F1 generations with other inbred C57BL/6 mice or transgenic littermates, respectively. Transmission of HBx gene in F1 offspring of X1, X5 and X9 except in X15 followed Mendelian rules. The expression of HBx mRNA was detected in liver of F1 offspring from the founder mice (X1 and X9), which showed vacuolation lesion and glycogen positive foci. CONCLUSION Transgenic mice harboring HBx gene were preliminarily established.

Detection of hyper-conserved regions in hepatitis B virus X gene potentially useful for gene therapy

AIM To detect hyper-conserved regions in the hepatitis B virus(HBV) X gene(HBX) 5' region that could be candidates for gene therapy.METHODS The study included 27 chronic hepatitis B treatmentnaive patients in various clinical stages(from chronic infection to cirrhosis and hepatocellular carcinoma, both HBeA g-negative and HBeA g-positive), and infected with HBV genotypes A-F and H. In a serum sample from each patient with viremia > 3.5 log IU/m L, the HBX 5' end region [nucleotide(nt) 1255-1611] was PCRamplified and submitted to next-generation sequencing(NGS). We assessed genotype variants by phylogenetic analysis, and evaluated conservation of this region by calculating the information content of each nucleotide position in a multiple alignment of all unique sequences(haplotypes) obtained by NGS. Conservation at the HBx protein amino acid(aa) level was also analyzed.RESULTS NGS yielded 1333069 sequences from the 27 samples, with a median of 4578 sequences/sample(2487-9279, IQR 2817). In 14/27 patients(51.8%), phylogenetic analysis of viral nucleotide haplotypes showed a complex mixture of genotypic variants. Analysis of the information content in the haplotype multiple alignments detected 2 hyper-conserved nucleotide regions, one in the HBX upstream non-coding region(nt 1255-1286) and the other in the 5' end coding region(nt 1519-1603). This last region coded for a conserved amino acid region(aa 63-76) that partially overlaps a Kunitz-like domain.CONCLUSION Two hyper-conserved regions detected in the HBX 5' end may be of value for targeted gene therapy, regardless of the patients' clinical stage or HBV genotype.

Characterization of hepatitis B virus X gene quasispecies complexity in mono-infection and hepatitis delta virus superinfection

Hepatitis delta virus(HDV) seems to strongly suppress hepatitis B virus(HBV)replication, although little is known about the mechanism of this interaction. Both these viruses show a dynamic distribution of mutants, resulting in viral quasispecies. Next-generation sequencing is a viable approach for analyzing the composition of these mutant spectra. As the regulatory hepatitis B X protein(HBx) is essential for HBV replication, determination of HBV X gene(HBX)quasispecies complexity in HBV/HDV infection compared to HBV monoinfection may provide information on the interactions between these two viruses.AIM To compare HBV quasispecies complexity in the HBX 5' region between chronic hepatitis delta(CHD) and chronic HBV mono-infected patients.METHODS Twenty-four untreated patients were included: 7/24(29.2%) with HBeAgnegative chronic HBV infection(CI, previously termed inactive carriers), 8/24(33.3%) with HBeAg-negative chronic hepatitis B(CHB) and 9/24(37.5%) with CHD. A serum sample from each patient was first tested for HBV DNA levels.The HBX 5' region [nucleotides(nt) 1255-1611] was then PCR-amplified for subsequent next-generation sequencing(MiSeq, Illumina, United States). HBV quasispecies complexity in the region analyzed was evaluated using incidencebased indices(number of haplotypes and number of mutations), abundancebased indices(Hill numbers of order 1 and 2), and functional indices(mutation frequency and nucleotide diversity). We also evaluated the pattern of nucleotide changes to investigate which of them could be the cause of the quasispecies complexity.RESULTS CHB patients showed higher median HBV-DNA levels [5.4 logIU/mL,interquartile range(IQR) 3.5-7.9] than CHD(3.4 logIU/mL, IQR 3-7.6)(P = n.s.)or CI(3.2 logIU/mL, IQR 2.3-3.5)(P < 0.01) patients. The incidence and abundance indices indicated that HBV quasispecies complexity was significantly greater in CI than CHB. A similar trend was observed in CHD patients, although only Hill numbers of order 2 showed statistically significant differences(CHB2.81, IQR 1.11-4.57 vs CHD 8.87, 6.56-11.18, P = 0.038). There were no significant differences in the functional indices, but CI and CHD patients also showed a trend towards greater complexity than CHB. No differences were found for any HBV quasispecies complexity indices between CHD and CI patients. G-to-A and C-to-T nucleotide changes, characteristic of APOBEC3 G, were higher in CHD and CI than in CHB in genotype A haplotypes, but not in genotype D. The proportion of nt G-to-A vs A-to-G changes and C-to-T vs T-to-C changes in genotype A and D haplotypes in CHD patients showed no significant differences. In CHB and CI the results of these comparisons were dependent on HBV genotype.CONCLUSION The lower-replication CHD and CI groups show a trend to higher quasispecies complexity than the higher-replication CHB group. The mechanisms associated with this greater complexity require elucidation.

Host cellular micro RNA involvement in the control of hepatitis B virus gene expression and replication

A large number of studies have demonstrated that the synergistic collaboration of a number of micro RNAs(mi RNAs), their growth factors and their downstream agents is required for the initiation and completion of pathogenesis in the liver. mi RNAs are thought to exert a profound effect on almost every aspect of liver biology and pathology. Accumulating evidence indicates that several mi RNAs are involved in the hepatitis B virus(HBV) life cycle and infectivity, in addition to HBVassociated liver diseases including fibrosis, cirrhosis and hepatocellular carcinoma(HCC). In turn, HBV can modulate the expression of several cellular mi RNAs, thus promoting a favorable environment for its replication and survival. In this review, we focused on the involvement of host cellular mi RNAs that are directly and indirectly associated with HBV RNA or HBV associated transcription factors. Exploring different facets of the interactions among mi RNA, HBV and HCV infections, and the carcinogenesis and progress of HCC, could facilitate the development of novel and effective treatment approaches for liver disease.

Upreguiation of human telomerase reverse transcriptase mRNA expression by in vitro transfection of hepatitis B virus X gene into human hepatocarcinoma and cholangiocarcinoma cells

AIM： To study the changes of human telomerase reverse transcriptase （hTERT） mRNA expression in human hepatocarcinoma cell lines （HepG2） and cholangiocarcinoma cell lines （QBC939） after HBx gene transfection and to illustrate the significance of transcriptional regulation of hTERT gene by HBx gene in the carcinogenesis. METHODS： HepG2 and QBC939 cell lines were cultured and co-transfected with eukaryotic expression vector containing the HBx coding region and cloning vector containing enhanced green fluorescent protein （EGFP） coding sequence using lipid-mediated gene transduction technique. Thirty-six hours after transfection, EGFP expression in cells was used as the indicator of successful transfection. Flow cytometry was performed to determine the transfection efficiency. Cells were harvested and total RNA was extracted using TRIzol reagent. The expression of hTERT mRNA in HepG2 and QBC939 cell lines was assayed by reverse transcriptionpolymerase chain reaction. The expression of HBx protein in both cell lines was detected by immunocytochemical staining and Western blotting. RESULTS： Flow cytometry showed that the transfection efficiency was 46.4% in HepG2 cells and 29.6% in QBC939 cells for both HBx gene expression vector and blank vector. The expression of hTERT mRNA was meaningfully increased in HepG2 and QBC939 cell lines when transfected with HBx gene expression vector compared to those transfected with OPTI-MEM medium and blank vector. Immunocytochemical staining and Western blotting revealed HBx protein expression in HepG2 and QBC939 cells only when transfected with HBx gene. CONCLUSION： HBx gene transfection can upregulate the transcriptional expression of hTERT mRNA. The transactivation of hTERT gene by HBx gene is a newfound mechanism for pathogenesis of hepatocarcinomas and cholangiocarcinomas after HBV infection. 2005 The WJG Press and Elsevier Inc. All rights reserved

Possible mechanism for hepatitis B virus X gene to induce apoptosis of hepatocytes

AIM： To investigate the possible mechanism for HBV X gene to induce apoptosis of hepatocyte HL-7702 cells.METHODS： HBV X gene eukaryon expression vector pcDNA3-X was established and transfected into HL-7702 cells by lipid-mediated transfection, including transient and stable transfection. Positive clones were screened by incubating in the selective medium with 600 μg/mL G418 and named HL-7702/HBV-encoded X protein （HBx） cells. The expressions of Fas/FasL, Bax/Bcl-2, and c-myc mRNA were measured by semi-quantitative RT-PCR in HL-7702/HBx and control group, respectively.RESULTS： RT-PCR analysis confirmed that HBV X gene was transfected into HL-7702 cells successfully. By semiquantitative RT-PCR analysis, Bax and c-myc mRNA levels in HL-7702/HBx cells of transient transfection were significantly higher than those in control, FasL and c-myc mRNA levels in HL-7702/HBx cells of stable transfection were significantly higher than those in control, whereas the Bcl-2 mRNA levels in HL-7702/HBx cells of transient and stable transfection were significantly lower than thosein control.CONCLUSION： HBV X gene may promote the apoptosis of hepatocytes by regulating the expressions of Fas/FasL, Bax/Bcl-2, and c-myc gene in a dose-dependent manner.

Biological impact of hepatitis B virus X-hepatitis C virus core fusion gene on human hepatocytes

AIM： To investigate the biological impact of hepatitis B virus X- hepatitis C virus core （HBV X-HCV C） fusion gene on hepatoma cells.METHODS： The recombinant adenoviruses Ad- XC, Ad-X and Ad-C expressing HBV X-HCV C fusion gene, HBVX gene and HCV C gene were constructed, respectively. Hepatoma cells were infected with different recombinant adenoviruses. MTT, colony- forming experiment, FCM, TUNEL assay were performed to observe the biological impact of the HBV X-HCV C fusion aene on liver cells.RESULTS： MTT showed that the Ad-XC group cells grew faster than the other group cells. Colony-forming experiment showed that the colony-forming rate for the Ad-XC group cells was significantly higher than that for the other group cells. FCM analysis showed that Ad-XC/Ad-X/Ad-C infection enhanced the progression of G1→S phase in the HepG2 cell cycle. The apoptosis index of the Ad-XC, Ad-X, Ad-C group cells was significantly lower than that of the AdO and control group cells. Semi-quantitative RT-PCR showed that the expression level of c-myc was the highest in Ad- XC infected cells. Tumor formation was found at the injected site of mice inoculated with Ad-XC-infected LO2 cells, but not in control mice.CONCLUSION： Ad-XC, Ad-X and Ad-C facilitate the proliferation activity of HepG2 cells and inhibit their apoptosis in vitro. The effect of Ad-XC is significantly stronger than that of Ad-X and Ad-C. Up-regulation of c-myc may be one of the mechanisms underlying the synergism of HBVX and HCV C genes on hepatocarcinogenesis in athymic nude mice.

Exploitation of host clock gene machinery by hepatitis viruses B and C

Many aspects of cellular physiology display circadian(approximately 24-h)rhythms.Dysfunction of the circadian clock molecular circuitry is associated with human health derangements,including neurodegeneration,increased risk of cancer,cardiovascular diseases and the metabolic syndrome.Viruses triggering hepatitis depend tightly on the host cell synthesis machinery for their own replication,survival and spreading.Recent evidences support a link between the circadian clock circuitry and viruses’biological cycle within host cells.Currently,in vitro models for chronobiological studies of cells infected with viruses need to be implemented.The establishment of such in vitro models would be helpful to better understand the link between the clock gene machinery and viral replication/viral persistence in order to develop specifically targeted therapeutic regimens.Here we review the recent literature dealing with the interplay between hepatitis B and C viruses and clock genes.

Transactivating effect of complete S protein of hepatitis B virus and cloning of genes transactivated by complete S protein using suppression subtractive hybridization technique

AIM: To investigate the transactivating effect of complete S protein of hepatitis B virus (HBV) and to construct a subtractive cDNA library of genes transactivated by complete S protein of HBV by suppression subtractive hybridization (SSH) technique and to clone genes associated with its transactivation activity, and to pave the way for elucidating the pathogenesis of hepatitis B virus infection. METHODS: pcDNA3.1(-)-complete S containing full-length HBV S gene was constructed by insertion of HBV complete S gene into BamH I/Kpn I sites. HepG2 cells were cotransfected with pcDNA3.1(-)-complete S and pSV-lacZ. After 48 h, cells were collected and detected for the expression of β-galactosidase (β-gal). Suppression subtractive hybridization and bioinformatics techniques were used. The mRNA of HepG2 cells transfected with pcDNA3.Incomplete S and pcDNA3.1(-) empty vector was isolated, and detected for the expression of complete S protein by reverse transcription polymerase chain reaction (RT-PCR) method, and cDNA was synthesized. After digestion with restriction enzyme RsaI, cDNA fragments were obtained. Tester cDNA was then divided into two groups and ligated to the specific adaptors 1 and 2, respectively. After tester cDNA had been hybridized with driver cDNA twice and underwent nested PCR twice, amplified cDNA fragments were subcloned into pGEM-Teasy vectors to set up the subtractive library. Amplification of the library was carried out within E. coli strain DH5α. The cDNA was sequenced and analyzed in GenBank with BLAST search after polymerase chain reaction (PCR) amplification. RESULTS: The complete S mRNA could be detected by RT-PCR in HepG2 cells transfected with the pcDNA3.1(-)-complete S. The activity of β-gal in HepG2 cells transfected with the pcDNA3.1(-)-complete s was 6.9 times higher than that of control plasmid. The subtractive library of genes transactivated by HBV complete S protein was constructed successfully. The amplified library contains 86 positive clones. Colony PCR showed that 86 clones contained DNA inserts of 200-1 000 bp, respectively. Sequence analysis was performed in 35 clones randomly, and the full length sequences were obtained with bioinformatics method and searched for homologous DNA sequence from GenBank, altogether 33 coding sequences were obtained. These cDNA sequences might be target genes transactivated by complete S protein of HBV. Moreover, two unknown genes were discovered, full length coding sequences were obtained by bioinformatics techniques, one of them was named complete S transactivated protein 1 (CSTP1) and registered in GenBank (AY553877). CONCLUSION: The complete S gene of HBV has a transactivating effect on SV40 early promoter. A subtractive cDNA library of genes transactivated by HBV complete S protein using SSH technique has been constructed successfully. The obtained sequences may be target genes transactivated by HBV complete S protein among which some genes coding proteins are involved in cell cycle regulation, metabolism, immunity, signal transduction, cell apoptosis and formation mechanism of hepatic carcinoma.

Silencing hepatitis B virus covalently closed circular DNA: The potential of an epigenetic therapy approach

Global prophylactic vaccination programmes have helped to curb new hepatitis B virus(HBV)infections.However,it is estimated that nearly 300 million people are chronically infected and have a high risk of developing hepatocellular carcinoma.As such,HBV remains a serious health priority and the development of novel curative therapeutics is urgently needed.Chronic HBV infection has been attributed to the persistence of the covalently closed circular DNA(cccDNA)which establishes itself as a minichromosome in the nucleus of hepatocytes.As the viral transcription intermediate,the cccDNA is responsible for producing new virions and perpetuating infection.HBV is dependent on various host factors for cccDNA formation and the minichromosome is amenable to epigenetic modifications.Two HBV proteins,X(HBx)and core(HBc)promote viral replication by modulating the cccDNA epigenome and regulating host cell responses.This includes viral and host gene expression,chromatin remodeling,DNA methylation,the antiviral immune response,apoptosis,and ubiquitination.Elimination of the cccDNA minichromosome would result in a sterilizing cure;however,this may be difficult to achieve.Epigenetic therapies could permanently silence the cccDNA minichromosome and promote a functional cure.This review explores the cccDNA epigenome,how host and viral factors influence transcription,and the recent epigenetic therapies and epigenome engineering approaches that have been described.

Relationship between hepatitis B virus associated primary hepatocellular carcinoma and alteration of tumor suppressor gene p53

Objective: To explore the changes and significance of tumor suppressor gene p53 in primary hepatocellu-lar carcinoma (PHC ) with hepatitis B virus (HBV ) infection. Methods: Tumor tissues and surrounding nontumortissues of sixteen PHC cases were studied by Southern hybridization to detect the state of HBV-DNA in tissues, byimmunohistochemical staining to determine HBsAg, HBxAg and p53 protein, and by PCR directed sequencing toanalyse the point mutation of p53 gene exons 5 to 8. Results: Among the 16 cases. 13 cases were HBV-DNA posi-tive, 10 tumor cases and 13 nontumor tissues cases HBxAg positive, and 9 cases posltive for p53 protein. The se-quencing of p53 gene point mutation was found in 5 cases, only one of which was sited at codon 249 G to T. Con-clusion: The mutation of p53 gene codon 249 is infrequent in HBV related PHC,indicating the accumulation of p53protein in cells may be associated with expression of HBxAg. HBxAg binding to p53 protein and inactivation of p53function play important roles in the development of PHC.

Identification of cellular genes showing differential expression associated with hepatitis B virus infection

AIM: To investigate the impact of hepatitis B virus (HBV) infection on cellular gene expression, by conducting both in vitro and in vivo studies. METHODS: Knockdown of HBV was targeted by stable expression of short hairpin RNA (shRNA) in huH-1 cells. Cellular gene expression was compared using a human 30K cDNA microarray in the cells and quantified by real-time reverse transcription-polymerase chain reaction (RT-PCR) (qRT-PCR) in the cells, hepatocellular carcinoma (HCC) and surrounding non-cancerous liver tissues (SL). RESULTS: The expressions of HBsAg and HBx protein were markedly suppressed in the cells and in HBx transgenic mouse liver, respectively, after introduction of shRNA. Of the 30K genes studied, 135 and 103 genes were identified as being down- and up-regulated, respectively, by at least twofold in the knockdown cells. Functional annotation revealed that 85 and 62 genes were classified into four up-regulated and five down-regulated functional categories, respectively. When gene expression levels were compared between HCC and SL, eight candidate genes that were confirmed to be up- or down-regulated in the knockdown cells by both microarray and qRT-PCR analyses were not expressed as expected from HBV reduction in HCC, but had similar expression patterns in HBV- and hepatitis C virus-associated cases. In contrast, among the eight genes, only APM2 was constantly repressed in HBV non-associated tissues irrespective of HCC or SL. CONCLUSION: The signature of cellular gene expression should provide new information regarding the pathophysiological mechanisms of persistent hepatitis and hepatocarcinogenesis that are associated with HBV infection.

Cloning and expression of the preS1 gene of hepatitis B virus in yeast cells

Objective: To investigate the complex functions of HBV preS1 protein, we constructed HBV preS1 gene expression vector and expressed it in yeast cells. Methods: Polymerase chain reaction (PCR) was per- formed to amplify the gene of HBV preS1 from the plasmid pCP10 containing the whole DNA fragment of HBV ayw subtype as template and the PCR prod- uct was cloned into the pGEM-T vector for sequen- cing. After being identified, the HBV preSl gene was cut from the pGEM-T vector by EcoR I and Pst I restriction enzymes, and cloned into yeast expres- sive plasmid pGBKT7 to constructe pGBKT7-preS1 recombinant expressive plasmid. This plasmid was transformed into yeast cell AH109 and expressed in it. The yeast protein was isolated and analyzed with sodium dodecyl suifate-polyacrylamide gel electro- phoresis(SDS-PAGE) and Western blotting. Results: The HBV preS1 gene was amplified success- fully and identified by DNA sequencing. The PCR products were coincided completely with the reported sequence. The digested fragments were cloned into the pGBKT7 vector and transformed into yeast cell AH109. The results of SDS-PAGE and Western blot- ting assay showed: (1) The HBV preS1 protein was expressed and existed in yeast cells; (2) The molecu- lar weight of the expression product was about 30 000 D. Conclusion: The HBV preS1 gene was successfully cloned and expressed in yeast cells.

Antiviral effects of hepatitis B virus S gene-specific anti-gene locked nucleic acid in transgenic mice

AIM To assess the antiviral effects of hepatitis B virus(HBV) S gene-specific anti-gene locked nucleic acid(LNA) in transgenic mice.METHODS Thirty HBV transgenic mice were acclimatized to laboratory conditions and positive for serum HBV surface antigen(HBs Ag) and HBV DNA, were randomly divided into 5 groups(n = 7), including negative control(blank control, unrelated sequence control), positive control(lamivudine, anti-sense-LNA), and anti-gene-LNA experimental group. LNA was injected into transgenic mice by tail vein while lamivudine was administeredby gavage. Serum HBV DNA and HBs Ag levels were determined by fluorescence-based PCR and enzymelinked immune sorbent assay, respectively. HBV S gene expression amounts were assessed by reverse transcription polymerase chain reaction. Positive rates of HBsA g in liver cells were evaluated immunohistochemistry.RESULTS Average rate reductions of HBs Ag after treatment on the 3 rd, 5 th, and 7 th days were 32.34%, 45.96%, and 59.15%, respectively. The inhibitory effect of antigene-LNA on serum HBs Ag peaked on day 7, with statistically significant differences compared with pretreatment(0.96 ± 0.18 vs 2.35 ± 0.33, P < 0.05) and control values(P < 0.05 for all). Average reduction rates of HBV DNA on the 3 rd, 5 th, and 7 th days were 38.55%, 50.95%, and 62.26%, respectively. This inhibitory effect peaked on the 7 th day after treatment with anti-gene-LNA, with statistically significant differences compared with pre-treatment(4.17 ± 1.29 vs 11.05 ± 1.25, P < 0.05) and control values(P < 0.05 for all). The mR NA levels of the HBV S gene(P < 0.05 for all) and rates of HBsA g positive liver cells(P < 0.05 for all) were significantly reduced compared with the control groups. Liver and kidney function, and histology showed no abnormalities. CONCLUSION Anti-gene-LNA targeting the S gene of HBV displays strong inhibitory effects on HBV in transgenic mice, providing theoretical and experimental bases for gene therapy in HBV.

Construction of a replication-competent hepatitis B virus vector carrying secreted luciferase transgene and establishment of new hepatitis B virus replication and expression cell lines

BACKGROUND Previously,we have successfully constructed replication-competent hepatitis B virus(HBV)vectors by uncoupling the P open reading frame(ORF)from the preC/C ORF to carefully design the transgene insertion site to overcome the compact organization of the HBV genome and maintain HBV replication competence.Consequently,the replication-competent HBV vectors carrying foreign genes,including pCH-BsdR,carrying blasticidin resistance gene(399 bp),and pCH-hrGFP,carrying humanized renilla green fluorescent protein gene(720 bp),were successfully obtained.However,the replication efficiency of the former is higher but it is tedious to use,while that of the latter is poor and cannot be quantified.Hence,we need to search for a new reporter gene that is convenient and quantifiable for further research.AIM To establish a helpful tool for intracellular HBV replication and anti-viral drugs screening studies.METHODS We utilized the replication-competent HBV viral vectors constructed by our laboratory,combined with the secreted luciferase reporter gene,to construct replication-competent HBV vectors expressing the reporter gene secretory Nanoluc Luciferase(SecNluc).HepG2.TA2-7 cells were transfected with this vector to obtain cell lines with stably secreted HBV particles carrying secNluc reporter gene.RESULTS The replication-competent HBV vector carrying the SecNluc reporter gene pCHsNLuc could produce all major viral RNAs and a full set of envelope proteins and achieve high-level secreted luciferase expression.HBV replication intermediates could be produced from this vector.Via transfection with pTRE-sNLuc and selection by hygromycin,we obtained isolated cell clones,named HBV-NLuc-35 cells,which could secrete secNLuc recombinant viruses,and were sensitive to existing anti-HBV drugs.Using differentiated HepaRG cells,it was verified that recombinant HBV possessed infectivity.CONCLUSION Our research demonstrated that a replication-competent HBV vector carrying a secreted luciferase transgene possesses replication and expression ability,and the established HBV replication and expression cell lines could stably secrete viral particles carrying secNluc reporter gene.More importantly,the cell line and the secreted recombinant viral particles could be used to trace HBV replication or infection.