Comparison among three new ways of antiviral activity about interferon alpha

AIM: To investigate the antiviral activity on Hepatitis B Virus and the gene responses of interferon alpha with different subtypes in vitro, and to assess the feasibility of using the signal transduction molecules as a new standard for evaluating the antiviral activities of IFN-α subtypes.

METHODS: After 2.2.15 cells were respectively treated with IFN-α 2b, IFN-α 2a, IFN-α 1b of varied concentrations (0.5,1,2, 4, 8 MU/L), the contents of HBsAg and HBeAg in the supernatant were measured by Abbot kit and the inhibitory rates on HBsAg and HBeAg were calculated. After HepG2 cells were treated with 1MU/L IFN-α 2b, IFN-α 2a, IFN-α 1b, the levels of STAT1, IFNAR mRNA and protein of were detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting.

RESULTS: The inhibitory rate of IFN-α 2b, IFN-α 2a, IFN-α 1b on HBsAg and HBeAg showed no statistical differences at the concentration of 0.5 or 1 MU/L. At the concentrations of 2, 4 and 8 MU/L, the inhibitory rate of IFN-α 1b was significantly higher than that of IFN-α 2b or IFN-α 2a (HBsAg: F = 4.51, 6.23; HBeAg: F = 3.11, 4.72, all P<0.05), while there was no significant difference between IFN-α 2b and IFN-α 2a. The levels of IFNAR, STAT1 mRNA and protein expressionwere slightly higher in IFN-α 1b group than that in IFN-α 2b group. However, the levels of mRNA and protein expression in IFN-α 1b or IFN-α 2b group markedly higher than that in IFN-α 2a group (mRNA: F = 5.26, 15.6; protein: F = 17.7, 20.1, all P<0.05).

CONCLUSION: IFN-α 1b and IFN-α 2b have stronger antiviral activity on HBV than IFN-α 2a. The signal transduction molecules (STAT1, IFNAR) are more sensitive in evaluating the antiviral activity of IFN-α.

Replication of hepatitis B virus in primary duck hepatocytes transfected with linear viral DNA

AIM: To explore the expression and replication of hepatitis B virus (HBV) DNA in primary duck hepatocytes (PDHs).

METHODS: Complete HBV genome was transfected into PDHs by electroporation (transfected group, 1.19×10¹² copies of linear HBV DNA/1×10⁷ PDHs). After 1-5 d of transfection, HBsAg and HBeAg in the supernatant and lysate of PDHs were measured with the IMX System. Meanwhile, replicative intermediates of HBV DNA were analyzed by Southern blotting and Dot blotting. PDHs electroporated were used as control group.

RESULTS: HBsAg in the hepatocyte lysates of transfected group was 15.24 (1 d), 14.55 (3 d) and 5.13 (5 d; P/N values, positive≥2.1) respectively. HBeAg was negative (<2.1). Both HBsAg and HBeAg were negative in the supernatant of transfected group. Dot blotting revealed that HBV DNA was strongly positive in the transfected group and negative in the control group. Southern blot analysis of intracellular total DNA indicated that there were relaxed circular (rc DNA), covalently closed circular (ccc DNA), and single-stranded (ss DNA) HBV DNA replicative intermediates in the transfected group, there was no integrated HBV DNA in the cellular genome. These parameters were negative in control group.

CONCLUSION: Expression and replication of HBV genes can occur in hepatocytes from non-mammalian species. HBV replication has no critical species-specificity, and yet hepatic-specific regulating factors in hepatocytes may be essential for viral replication.

Misperceptions among patients with chronic hepatitis B in Singapore

AIM: To identify the misperceptions among CHB patients, as well as to determine the factors associated with better knowledge.

METHODS: A telephone interview was conducted on 192 adult CHB patients, who earlier responded to an advertisement for free screening. The questionnaire included items about socio-demographic factors and a 14-item quiz on knowledge of general aspects, transmission, and management of HBV infection.

RESULTS: The mean knowledge score on HBV was 10.4/14. Common misperceptions included availability of treatment for HBV infection and early liver cancer, as well as on transmission. Having completed tertiary education was the only independent factor associated with a high knowledge score, after controlling other demographic factors.

CONCLUSION: More educational efforts should be focused on patients misperceptions and target the less educated HBV carriers.

Mutations in hepatitis B virus core regions correlate with hepatocellular injury in Chinese patients with chronic hepatitis B

AIM: To elucidate the relationship between the frequency of core mutations and the clinical activity of hepatitis B virus (HBV)-related liver disease and to characterize the amino acid changes in the core region of HBV.

METHODS: We studied 17 Chinese patients with chronic hepatitis B according to their clinical courses and patterns of the entire core region of HBV.

RESULTS: Amino acid changes often appeared in the HBV core region of the HBV gene in patients with high values of alanine aminotransferase (ALT) or with the seroconversion from HbeAg to anti-HBe. The HBV core region with amino acid changes had high frequency sites that corresponded to HLA I/II restricted recognition epitopes reported by some investigators.

CONCLUSION: The core amino acid changes of this study occur due to influence of host immune system. The presence of mutations in the HBV core region seems to be important for predicting the clinical activity of hepatitis B in Chinese patients.

Biological impacts of “hot-spot” mutations of hepatitis B virus X proteins are genotype B and C differentiated

AIM: To investigate the biological impacts of “hot-spot” mutations on genotype B and C HBV X proteins (HBx).

METHODS: Five types of “hot-spot” mutations of genotype B or C HBV X genes, which sequentially lead to the amino acid substitutions of HBx as I127T, F132Y, K130M+V131I, I127T+K130M+V131I, or K130M+V131I+F132Y, respectively, were generated by means of site-directed mutagenesis. To evaluate the anti-proliferative effects, HBx or related mutants’ expression vectors were transfected separately to the Chang cells by lipofectamine, and the cells were cultured in hygromycin selective medium for 14 d, drug-resistant colonies were fixed with cold methanol, stained with Giemsa dyes and scored (increase of the colonies indicated the reduction of the anti-proliferation activity, and vice versa). Different types of HBx expression vectors were co-transfected separately with the reporter plasmid pCMVβ to Chang cells, which were lysed 48 h post-transfection and the intra-cellular β-galactosidase activities were monitored (increase of the β-galactosidase activities indicated the reduction of the transactivation activity, and vice versa). All data obtained were calculated by paired-samples t-test.

RESULTS: As compared to standard genotype B HBx, mutants of I127T and I127T+K130M+V131I showed higher transactivation and anti-proliferative activities, while the mutants of F132Y, K130M+V131I, and K130M+V131I+F132Y showed lower activities. As compared to standard genotype C HBx, I127T mutant showed higher transactivation activity, while the other four types of mutants showed no differences. With regard to anti-proliferative activity, compared to standard genotype C HBx, F132Y and K130M+V131I mutants showed lower activities, and K130M+V131I +F132Y mutant, on the other hand, showed higher activity, while the mutants of I127T and I127T+K130M+V131I showed no differences.

CONCLUSION: “Hot-spot” mutations affect the anti-proliferation and transactivation activities of genotype B and/or C HBx, and the biological impacts of most “hot-spot” mutations on HBx are genotype B and C differentiated.

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 mg/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 semi-quantitative 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 those in 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.

Screening for PreS specific binding ligands with a phage displayed peptides library

AIM: To construct a random peptide phage display library and search for peptides that specifically bind to the PreS region of hepatitis B virus (HBV).

METHODS: A phage display vector, pFuse8, based on the gene 8 product (pVIII) of M13 phage was made and used to construct a random peptide library. E.coli derived thioredoxin-PreS was purified with Thio-bond beads, and exploited as the bait protein for library screening. Five rounds of bio-panning were performed. The PreS-binding specificities of enriched phages were characterized with phage ELISA assay.

RESULTS: A phage display vector was successfully constructed as demonstrated to present a pVIII fused HBV PreS1 epitope on the phage surface with a high efficiency. A cysteine confined random peptide library was constructed containing independent clones exceeding 5±10⁸ clone forming unit (CFU). A pool of phages showing a PreS-binding specificity was obtained after the screening against thio-PreS with an enrichment of approximately 400 times. Five phages with high PreS-binding specificities were selected and characterized. Sequences of the peptides displayed on these phages were determined.

CONCLUSION: A phage library has been constructed, with random peptides displaying as pVIII-fusion proteins. Specific PreS-binding peptides have been obtained, which may be useful for developing antivirals against HBV infection.

Screening of hepatocyte proteins binding to complete S protein of hepatitis B virus by yeast-two hybrid system

AIM: To investigate the biological function of complete S protein and to look for proteins interacting with complete S protein in hepatocytes.

METHODS: We constructed bait plasmid expressing complete S protein of HBV by cloning the gene of complete S protein into pGBKT7, then the recombinant plasmid DNA was transformed into yeast AH109 (a type). The transformed yeast AH109 was mated with yeast Y187 (α type) containing liver cDNA library plasmid in 2 ×YPDA medium. Diploid yeast was plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing X-α-gal for selection and screening. After extracting and sequencing of plasmids from positive (blue) colonies, we underwent sequence analysis by bioinformatics.

RESULTS: Nineteen colonies were selected and sequenced. Among them, five colonies were Homo sapiens solute carrier family 25, member 23 (SLC25A23), one was Homo sapiens calreticulin, one was human serum albumin (ALB) gene, one was Homo sapiens metallothionein 2A, two were Homo sapiens betaine-homocysteine methyltransferase, three were Homo sapiens Na⁺ and H⁺ coupled amino acid transport system N, one was Homo sapiens CD81 antigen (target of anti-proliferative antibody 1) (CD81), three were Homo sapiens diazepam binding inhibitor, two colonies were new genes with unknown function.

CONCLUSION: The yeast-two hybrid system is an effective method for identifying hepatocyte proteins interacting with complete S protein of HBV. The complete S protein may bind to different proteins i.e., its multiple functions in vivo.

Depletion of CD25+CD4+T cells (Tregs) enhances the HBV-specific CD8+ T cell response primed by DNA immunization

AIM: Persistent hepatitis B virus (HBV) infection is characterized by a weak CD8⁺ T cell response to HBV. Immunotherapeutic strategies that overcome tolerance and boost these suboptimal responses may facilitate viral clearance in chronically infected individuals. Therefore, we examined whether CD25⁺CD4⁺ regulatory T (Treg) cells might be involved in a inhibition of CD8⁺ T cell priming or in the modulation of the magnitude of the ‘peak’ antiviral CD8⁺ T cell response primed by DNA immunization.

METHODS: B10.D2 mice were immunized once with plasmid pCMV-S. Mice received 500 μg of anti-CD25 mAb injected intraperitoneally 3 d before DNA immunization to deplete CD25⁺ cells. Induction of HBV-specific CD8⁺ T cells in peripheral blood mononuclear cells (PBMCs) was measured by S28-39 peptide loaded DimerX staining and their function was analyzed by intracellular IFN-γ staining.

RESULTS: DNA immunization induced HBV-specific CD8⁺ T cells. At the peak T cell response (d 10), 7.1±2.0% of CD8⁺ T cells were HBV-specific after DNA immunization, whereas 12.7±3.2% of CD8⁺ T cells were HBV-specific in Treg-depleted mice, suggesting that DNA immunization induced more antigen-specific CD8⁺ T cells in the absence of CD25⁺ Treg cells (n = 6, P<0.05). Similarly, fewer HBV-specific memory T cells were detected in the presence of these cells (1.3±0.4%) in comparison to Treg-depleted mice (2.6±0.9%) on d 30 after DNA immunization (n = 6, P<0.01). Both IFN-γ production and the avidity of the HBV-specific CD8⁺ T cell response to antigen were higher in HBV-specific CD8⁺ T cells induced in the absence of Treg cells.

CONCLUSION: CD25⁺ Treg cells suppress priming and/or expansion of antigen-specific CD8⁺ T cells during DNA immunization and the peak CD8⁺ T cell response is enhanced by depleting this cell population. Furthermore, Treg cells appear to be involved in the contraction phase of the CD8⁺ T cell response and may affect the quality of memory T cell pools. The elimination of Treg cells or their inhibition may be important in immunotherapeutic strategies to control HBV infection by inducing virus-specific cytotoxic T lymphocyte responses in chronically infected subjects.

Optimization of competitively differentiated polymerase chain reaction in detection of HBV basal core promoter mutation

AIM: To improve competitively differentiated polymerase chain reaction (CD-PCR) in detection of HBV basal core promoter mutation.

METHODS: Recombinant plasmid of double point mutation A1762T/G1764A in basal core promoter of HBV constructed by site-directed mutagenesis was used as mutant control. To reveal the deficiency mechanism of CD-PCR, relationship between the circle number of PCR and the increased speed of products of each competitive primer was comparatively studied. Diversified amount of dNTPs and mutual primer of the competitive primers were tried to optimize CD-PCR. Optimized CD-PCR was evaluated by detecting A1762T/G1764A mutation in recombinant plasmids and clinical sera from patients with HBV infection.

RESULTS: The deficiency mechanism of CD-PCR was that the products of mismatched competitive primer grew fast when the amplification of matched primer entered into plateau stage, which led to decrease in or disappearance of the difference in the amount of their products. This phenomenon could be eliminated by reducing dNTPs to 10 μmol/L and mutual primer to about 100 nmol/L. Optimized CD-PCR could detect both mutant and wild strain indepe-ndent of the amount of templates and the number of PCR cycles. Its detection limit was 10³ copies/mL, about 50 copies/reaction. About 10% of mutant DNAs among wild type DNAs could be detected. A1762T/G1764A mutant was detected in 41.8% (51/122) of patients with HBV infection, but not detected in controls with negative HBsAg.

CONCLUSION: Optimized CD-PCR can detect mutation independent of the amount of initial templates and the number of PCR cycles.

Molecular epidemiological study on pre-X region of hepatitis B virus and identification of hepatocyte proteins interacting with whole-X protein by yeast two-hybrid

AIM: To identify the pre-X region in hepatitis B virus (HBV) genome and to study the relationship between the genotype and the pre-X region. To investigate the biological function of whole-X (pre-X plus X) protein, we performed yeast two-hybrid to screen proteins in liver interacting with whole-X protein.

METHODS: The pre-X region of HBV was amplified by polymerase chain reaction (PCR) method, and was cloned to pGEM Teasy vector. After the target region was sequenced, Vector 8.0 software was used to analyze the sequences. The whole-X bait plasmid was constructed by using yeast two-hybrid system 3. Yeast strain AH109 was transformed. After expression of the whole-X protein in AH109 yeast strains was proved, yeast two-hybrid screening was performed by mating AH109 with Y187 containing liver cDNA library plasmid. The mated yeast was plated on quadruple dropout medium and assayed for α-gal activity. The interaction between whole-X protein and the protein obtained from positive colonies was further confirmed by repeating yeast two-hybrid. After extracting and sequencing of plasmid from blue colonies, we carried out analysis by bioinformatics.

RESULTS: After sequencing, 27 of 45 clones (60%) were found encoding the pre-X peptide. Eighteen of twenty-seven clones (66.7%) of pre-X coding sequences were found from genotype C. Five positive colonies that interacted with whole-X protein were obtained and sequenced; namely, fetuin B, UDP glycosyltransferase 1 family-polypeptide A9, mannose-P-dolichol utilization defect 1, fibrinogen-B beta polypeptide, transmembrane 4 superfamily member 4-CD81 (TM4SF4).

CONCLUSION: The pre-X gene exists in HBV genome. Genes of proteins interacting with whole-X protein in hepatocytes were successfully cloned. These results brought some new clues for studying the biological functions of whole-X protein.

High level of hepatitis B virus DNA after HBeAg-to-anti-HBe seroconversion is related to coexistence of mutations in its precore and basal core promoter

AIM: G1896A mutation in precore or A1762T/G1764A mutations in basal core promoter are suspected to be responsible for patients with detectable level of HBV DNA in serum after seroconversion from HBeAg to anti-HBe. However, G1896A variant has impaired, while A1762T/G1764A variant may have intact replication ability. They themselves or their coexistence status may play different roles in such meaningless seroconversion. For these reasons, the significances of these two types of mutations were comparatively investigated in this study.

METHODS: One hundred and sixty-five sera with positive anti-HBe and HBV DNA were collected from different patients. Mutations of G1896A and A1762T/G1764A among these serum samples were detected using competitively differentiated PCR. HBV DNA was demonstrated using real-time quantitative PCR.

RESULTS: G1896A and/or A1762T/G1764A mutations were detected in 89.1% (147/165) out of patients with detectable HBV DNA in serum after HBeAg-to-anti-HBe seroconversion. The positive rate of G1896A variants was significantly higher than that of A1762T/G1764A mutations (77.6% vs 50.3%, χ² = 26.61, P<0.01). The coexistence positive rate of these two types of mutations was 38.8% (64/165). Coexistence mutations were found in 77.1% (64/83) out of sera with A1762T/G1764A mutations, and in 50.0% (64/128) out of sera with G1896A mutation. Compared with variants with G1896A mutation only, the coexistence mutations were predominant in patients with high level of serum HBV DNA, and related to higher total bilirubin, lower serum albumin and progressive liver diseases.

CONCLUSION: The coexistence of G1896A mutation and A1762T/G1764A mutations is very common, and responsible for the major cases with high level of HBV DNA in serum and progressive liver diseases after HBeAg-to-anti-HBe seroconversion. This coexistence mutation variant may have higher pathogenicity and replication ability.

Expression and purification of the complete PreS region of hepatitis B Virus

AIM: To express the complete PreS region of HBV in E.coli with good solubility and stability, and to establish an effective method for purification of the recombinant PreS protein.

METHODS: The complete PreS region (PreS1 and PreS2) was fused into a series of tags including glutathione S-transferase (GST), dihydrofolate reductase (DHFR), maltose binding protein (MBP), 6×histidine, chitin binding domain (CBD), and thioredoxin, respectively. Expression of recombinant PreS fusion proteins was examined by SDS-PAGE analysis and confirmed by Western blot. Two fusion proteins, thio-PreS, and PreS-CBD, with desirable solubility and stability, were subjected to affinity purification and further characterization.

RESULTS: Recombinant PreS fusion proteins could be synthesized with good yields in E.coli. However, most of these proteins except for thio-PreS and PreS-CBD were vulnerable to degradation or insoluble as revealed by SDS-PAGE and Western blot. Thio-PreS could be purified by affinity chromatography with nickel-chelating sepharose as the matrix. However, some impurities were also co-purified. A simple freeze-thaw treatment yielded most of the thio-PreS proteins in solution while the impurities were in the precipitate. Purified thio-PreS protein was capable of inhibiting the binding of HBV virion to a specific monoclonal antibody against an epitope within the PreS1 domain.

CONCLUSION: Increased solubility and stability of the complete PreS region synthesized in E.coli can be achieved by fusion with the thioredoxin or the CBD tag. A simple yet highly effective method has been established for the purification of the thio-PreS protein. Purified thio-PreS protein likely assumes a native conformation, which makes it an ideal candidate for studying the structure of the PreS region as well as for screening antivirals.

Hydrophobicity of reactive site loop of SCCA1 affects its binding to hepatitis B virus

AIM: To investigate the role of SCCA2 and other SCCA1 molecules in the process of hepatitis B virus (HBV) binding to mammalian cells.

METHODS: SCCA1 and SCCA2 were isolated from HepG2. Binding protein (BP) genes were obtained through PCR. Recombinant baculoviruses expressing SCCA1, SCCA2, BP, and different mutants were constructed and utilized to infect mammalian cells to investigate the binding ability of infected cells to HBV.

RESULTS: A SCCA1 gene (A1) was isolated from HepG2, but it appeared to lack the binding ability of infected cells to HBV. Two mutants, A1-BP and BP-A1, were constructed by interchanging the carboxyl terminal of A1 and BP. Cells expressing A1-BP showed an increased virus binding capacity, but not BP-A1. Comparison of A1 sequence with the sequence of BP indicated the presence of only three amino acid changes in the carboxyl terminal, two of them were found in the reactive site loop (RSL) of SCCA1. Primary structure assay revealed that the hydrophobicity of BP and AJ515706 in this domain was strong, but A1 was relatively weak. Changing the aa349 of A1 from low hydrophobic glutamic acid to high hydrophobic valine enhanced HBV binding. In contrast, HBV binding was reduced by changing the aa349 of BP from valine to glutamic acid.

CONCLUSION: The results suggest that the hydrophobicity of RSL of SCCA1 may play an important role in HBV binding to cells.

Predictive value of HBV cccDNA in PBMC of response to lamivudine therapy in patients with chronic hepatitis B

AIM: To assess the value of hepatitis B virus (HBV) covalently closed circle DNA (cccDNA) in peripheral blood mononuclear cells (PBMC) for the prediction of the sustained response to lamivudine therapy in patients with chronic hepatitis B.

METHODS: Seventeen chronic hepatitis B patients with complete or partial response (serum HBV DNA turned negative, and ALT was normalized with or without HBeAg/anti-HBe seroconversion) were selected. HBV cccDNA in PBMC was detected at the end of lamivudine treatment, and 1 year after treatment.

RESULTS: Nine out of 17 patients were positive for HBV cccDNA in their PBMC at the end of lamivudine treatment. Virological relapse were found during 1-year follow-up in all of these 9 patients; whereas only 1 relapse was observed among the 8 patients without HBV cccDNA.

CONCLUSION: HBV cccDNA in PBMC at the end of treatment is of good predictive value for the sustained response to lamivudine treatment in chronic hepatitis B patients.

Clinical analysis of the risk factors for recurrence of HCC and its relationship with HBV

AIM: To comprehend the risk factors of recurrence of hepatocellular carcinoma (HCC) and its relationship with the infection patterns of hepatitis B virus (HBV).

METHODS: All materials of 270 cases of postoperative HCC were statistically analyzed by SPSS software. Recurrence and metastasis were classified into early ( ≤2 years) and late phase (>2 years). Risk factors for recurrence and metastasis after surgery in each group were analyzed.

RESULTS: Out of 270 cases of HCC, 162 cases were followed up in which recurrence and metastasis occurred in 136 cases. There were a lot of risk factors related to recurrence and metastasis of HCC; risk factors contributing to early phase recurrence were serum AFP level, vascular invasion, incisal margin and operative transfusion, gross tumor classification and number of intrahepatic node to late phase recurrence. The HBV infective rate of recurrent HCC was 94.1%, in which “HBsAg, HBeAb, HBcAb” positive pattern reached 45.6%. The proportion of HBV infection in solitary large hepatocellular carcinoma (SLHCC) evidently decreased compared to nodular hepatocellular carcinoma (NHCC) (P<0.05).

CONCLUSION: The early and late recurrence and metastasis after hepatectomy of HCC were associated with different risk factors. The early recurrence may be mediated by vascular invasion and remnant lesion, the late recurrence by tumor’s clinical pathology propert, as multicentric carcinogenesis or intrahepatic carcinoma de novo. HBV replication takes a great role in this process. From this study, we found that SLHCC has more satisfactory neoplasm biological behavior than NHCC.

Clinical significance of hepatic derangement in severe acute respiratory syndrome

AIM: Elevation of alanine aminotransferase (ALT) level is commonly seen among patients suffering from severe acute respiratory syndrome (SARS). We report the progression and clinical significance of liver derangement in a large cohort of SARS patient.

METHODS: Serial assay of serum ALT was followed in patients who fulfilled the WHO criteria of SARS. Those with elevated ALT were compared with those with normal liver functions for clinical outcome. Serology for hepatitis B virus (HBV) infection was checked. Adverse outcomes were defined as oxygen desaturation, need of intensive care unit (ICU) and mechanical ventilation and death.

RESULTS: Two hundred and ninety-four patients were included in this study. Seventy (24%) patients had elevated serum ALT on admission and 204 (69%) patients had elevated ALT during the subsequent course of illness. Using peak ALT > 5×ULN as a cut-off and after adjusting for potential confounding factors, the odds ratio of peak ALT > 5×ULN for oxygen desaturation was 3.24 (95%CI 1.23-8.59, P = 0.018), ICU care was 3.70 (95%CI 1.38-9.89, P = 0.009), mechanical ventilation was 6.64 (95%CI 2.22-19.81, P = 0.001) and death was 7.34 (95%CI 2.28-24.89, P = 0.001). Ninety-three percent of the survived patients had ALT levels normalized or were on the improving trend during follow-up. Chronic hepatitis B was not associated with worse clinical outcomes.

CONCLUSION: Reactive hepatitis is a common complication of SARS-coronavirus infection. Those patients with severe hepatitis had worse clinical outcome.

“Defective” mutations of hepatitis D viruses in chronic hepatitis D patients

AIM: To verify whether “defective” mutations existed in hepatitis D virus (HDV).

METHODS: Hepatitis delta antigen (HDAg)-coding sequences were amplified using Pfu DNA polymerases with proof-reading activities from sera of five patients with chronic hepatitis D. Multiple colonies were sequenced for each patient. Pfu analyzed a total of 270 HDV clones. Three representative defective HDV clones were constructed in expression plasmids and transfected into a human hepatoma cell line. Cellular proteins were extracted and analyzed by Western blot.

RESULTS: Four of five cases (80%) showed defective HDV genomes in their sera. The percentage of defective genomes was 3.7% (10/270). The majority (90%) of the defective mutations were insertions or deletions that resulted in frameshift and abnormal stop translation of the HDAg. The predicted mutated HDAg ranged from 45 amino acids to >214 amino acids in length. Various domains of HDAg associated with viral replication or packaging were affected in different HDV isolates. Western blot analysis showed defected HDAg in predicted positions.

CONCLUSION: “Defective” viruses do exist in chronic HDV infected patients, but represented as minor strains. The clinical significance of the “defected” HDV needs further study to evaluate.

Mutation of hepatitis B virus with treatment of interferon

AIM: To investigate the mutation of hepatitis B virus (HBV) with the treated with interferon (IFN)-α2b.

METHODS: Different doses of IFN-α2b were added to the HepG2.2.15 cell culture. The α-fetoprotein (AFP) in the supernatant was assayed by Western blot. HBV DNA was isolated from the culture medium. HBV C gene amplified by PCR was cloned by T-A cloning into pGEM-T easy vector. The recombinatant was sequenced with T7/SP6 primer, and analyzed by DNA software.

RESULTS: AFP in the culture medium was detected, which was not reduced after IFN-α treatment. There were two subtypes of preC/C gene in the control group. The homogeneity was 93%, with 10 amino acids different, 6 of which were of identical characteristics. The same subtypes were found in the experiment group. The proportion of the dominant strain gene was altered in the high dose IFN group. There were 4 insertion/ deletion mutations in the high dose IFN experiment group, which resulted in reading frame shift. The mean homogeneity was more than 97%.

CONCLUSION: HBV pre-C/C gene insertion/deletion mutants exist in HepG2.2.15 cells treated with high dose IFN-α. Compared with the dominant strain, the mean homogeneity of the mutant strain was more than 97%.

Effects of HBV infection on T cell immunity and hepatic expression of TNF-α and TGF-β2

AIM: To study the influence of hepatitis B virus(HBV) infection on cellular immunity via examining the T cell subsets in peripheral blood and the hepatic tissues and the expression of cytokines in the liver.

METHODS: CD4⁺ T cells and CD8⁺ T cells in peripheral blood was enumerated by flow cytometry (FCM) in 36 patients with hepatitis B and 20 healthy controls. The expression of CD4, CD8, CD25, TNF-α and TGF-β2 were determined by streptavidin-peroxidase (SP) immunohistochemistry in 50 cases HBV-infected liver tissues.

RESULTS: The quantity of CD4⁺ T cells and the ratio of CD4⁺/CD8⁺ in peripheral blood of patients were significantly lower than controls (P<0.05). The quantity of CD8⁺ T cells was considerably higher than controls (P<0.05). T cells mostly accumulated in the lobule and the portal tract. More CD8⁺ cells than CD4⁺ cells were observed. The quantities of CD4⁺ and CD8⁺ cells in the liver tissues of HBV positive group were significantly different from the negative group(P<0.05). CD25⁺ cells were reduced in the infected livers, but without significant difference. The expression of TNF-α in the liver tissues of HBV positive group were significantly different from the liver tissues of HBV negative group(P<0.05). In contrast, the expression of TGF-β2 was not significantly different between the two groups. TGF-β2 and TNF-α expression in liver cirrhosis, hepatocellular carcinoma and paratumor cirrhosis were significantly different from that in control group(P<0.01).

CONCLUSION: Aberrant T cell subsets and reduced T cell activity exist in patients with HBV infection. TNF-α, but not TGF-β2, may be related to HBV infection and liver injury.

Hepatitis B virus infection and coronary atherosclerosis: Results from a population with relatively high prevalence of hepatitis B virus

AIM: To investigate the possible association between hepatitis B virus (HBV) infection and angiographically proven coronary artery disease (CAD) in a population with relatively high prevalence of HBV.

METHODS: Sera from 434 patients who underwent coronary angiography were tested for HBV antigens (HBsAg, HBeAg) and antibodies (Anti-HBs, Anti-HBc and Anti-HBe) by ELISA.

RESULTS: Seventy-seven percent (224/291) of the patients with CAD and 73.4% (105/143) of the patients without angiographic evidence of atherosclerosis were seropositive for HBV (P>0.05). However, C-reactive protein (CRP) levels were significantly higher in patients with CAD (P = 0.008), while lower in HBV seropositive population (P = 0.043 and P = 0.021 after adjustment for conventional risk factors).

CONCLUSION: Our results suggested HBV infection negatively correlates with CRP levels, but seems not to be associated with coronary atherosclerosis.

The laboratory diagnosis of hepatitis B virus

Hepatitis B virus (HBV) chronically infects approximately 250,000 Canadians and 350 million people worldwide. Without intervention, approximately 15% to 40% of chronically infected individuals will eventually develop cirrhosis, end-stage liver disease or hepatocellular carcinoma, or require liver transplantation. The availability and extensive use of the HBV vaccine has dramatically reduced the number of incident infections in Canada and worldwide. Effective therapeutic agents have been and continue to be developed to treat chronic infection. The present review provides a comprehensive overview of diagnostic tests for HBV infection and immunity, and elaborates on HBV risk factors, vaccine prevention and therapeutic monitoring. HBV diagnosis is accomplished by testing for a series of serological markers of HBV and by additional testing to exclude alternative etiological agents such as hepatitis A and C viruses. Serological tests are used to distinguish acute, self-limited infections from chronic HBV infections and to monitor vaccine-induced immunity. Nucleic acid testing for HBV-DNA is increasingly being used to quantify HBV viral load and measure the effectiveness of therapeutic agents. Given the multitude of available tests and the complexity of clinical management, there is a critical need for greater coordination among clinicians, diagnostic laboratory personnel and researchers to define optimal laboratory diagnostic and monitoring assays so that the appropriate tests are used to maximize prevention and optimize treatment outcomes.

YMDD mutations in patients with chronic hepatitis B untreated with antiviral medicines

AIM: To polymerase P region (YMDD) mutations of hepatitis B virus gene (HBV DNA) in patients with chronic hepatitis B (CHB) untreated with antiviral medicines and to explore its correlation with pre-c-zone mutations, HBV genotypes and HBV DNA level, and to observe its curative effect.

METHODS: A total of 104 cases (38 cases in group of familial aggregation and 66 cases in group of non-familial aggregation) were randomly chosen from 226 patients with CHB who did not receive the treatment of lamivudine (LAM) and any other antivirus drugs within the last one year. Their serum YMDD mutations were detected by microcosmic nucleic acid and cross-nucleic acid quantitative determination, HBV genotypes by PCR-microcosmic nucleic acid cross-ELISA, HBV DNA quantitative determination and fluorescence ration PCR analysis, hepatitis B virus markers (HBVM) by ELISA. LAM was taken by 10 patients with YMDD mutations and its curative effect was observed.

RESULTS: Twenty-eight cases (26.9%) had YMDD mutations, of them 11 cases (28.9%) were in familial aggregation group (38 cases) and 17 cases (25.8%) in non-familial aggregation group (66 cases) with no significant difference between the two groups. Twenty-seven point one percent (16/59) cases were positive for HBeAg YMDD mutations, and 26.7% (12/45) cases were negative for HBeAg and positive for anti-HBe. There was also no significant difference between the two groups. Different YMDD incidence rate existed in different HBV genotypes. HBV DNA level did not have a positive correlation with the incidence of YMDD mutations. LAM was effective for all patients with mutations.

CONCLUSION: Wild mutant strains in HBV and their incidence rate have no significant difference between familial aggregation and non-familial aggregation. It may have no significant relationship between YMDD mutations and pre-c-zone mutations. HBV DNA level may not have a positive correlation with YMDD mutations. LAM is clinically effective for CHB patients with YMDD mutations.

In vitro resistance to interferon of hepatitis B virus with precore mutation

AIM: Chronic hepatitis B virus (HBV) infection is predominantly treated with interferon alpha (IFN-α), which results in an efficient reduction of the viral load only in 20-40% of treated patients. Mutations at HBV precore prevail in different clinical status of HBV infection. The roles of precore mutation in the progression of chronic hepatitis and interferon sensitivity are still unknown. The aim of this study was to explore if there was any relationship between HBV precore mutation and sensitivity to interferon in vitro.

METHODS: HBV replication-competent recombinant constructs with different patterns of precore mutations were developed. Then the recombinants were transiently transfected into hepatoma cell line (Huh7) by calcium phosphate transfection method. With or without IFN, viral products in culture medium were collected and quantified 3 d after transfection.

RESULTS: We obtained 4 recombinant constructs by orientation-cloning 1.2-fold-overlength HBV genome into pUC18 vector via the EcoRI and Hind III and PCR mediated site-directed mutagenesis method. All the recombinants contained mutations within precore region. Huh7 cells transfected with recombinants secreted HBsAg and HBV particles into the cell culture medium, indicating that all the recombinants were replication-competent. By comparing the amount of HBV DNA in the medium, we found that HBV DNA in medium reflecting HBV replication efficiency was different in different recombinants. Recombinants containing precore mutation had fewer HBV DNAs in culture medium than wild type. This result showed that recombinants containing precore mutation had lower replication efficiency than wild type. HBV DNA was decreased in pUC18-HBV1.2-WT recombinants after IFN was added while others with precore mutations were not, indicating that HBV harboring precore mutation was less sensitive to IFN in cell culture system.

CONCLUSION: These data indicate that HBV harboring precore mutation may be resistant to IFN in vitro.

Comparison of target genes transactivated by different spliced transcripts of human NS5ATP2

AIM: To identify and analyze target genes regulated by different spliced transcripts of human NS5ATP2 by microarray technique.

METHODS: The coding sequences for the two differently spliced transcripts of human NS5ATP2, NS5ATP2 (615) and NS5ATP2, were cloned into eukaryotic expression vector pcDNA3.1 to yield pcDNA3.1-NS5ATP2 (615) and pcDNA3.1-NS5ATP2 (216) constructs, which were then transfected into HepG2 cells. The differentially expressed genes in the cells transfected with the two differently spliced variants were analyzed and compared by DNA microarray.

RESULTS: Forty-three genes were up-regulated by both NS5ATP2 (615) and NS5ATP2 (216), and 13 genes were down-regulated by both NS5ATP2 (615) and NS5ATP2 (216). Meanwhile, 3 genes were found to be up-regulated by NS5ATP2 (615), but down-regulated by NS5ATP2 (216). No genes were down-regulated by NS5ATP2 (615) while up-regulated by NS5ATP2 (216). Many genes were trans-regulated by NS5ATP2 (615) or NS5ATP2 (216) independently.

CONCLUSION: Different spliced transcripts of human NS5ATP2 may commonly or independently regulate target genes. They even exhibit opposite regulatory effects upon some target genes.

Incidence of HBV variants with a mutation at nt551 among hepatitis B patients in Nanjing and its neighbourhood

AIM: To investigate the epidemiology of hepatitis B virus (HBV) strains with a mutation at nt551 in surface gene among hepatitis B patients in Nanjing and its neighbourhood.

METHODS: By using mutation-specific polymerase chain reaction (msPCR) established by our laboratory for amplifying HBV DNAs with a mutation at nt551, 117 serum samples taken from hepatitis B patients were detected.

RESULTS: The results showed that 112 samples were positive for nt551A, 4 samples were positive for nt551G. One sample was positive for nt551T. No nt551C of HBV DNA was found. The incidence of HBsAg mutants with G, C, T, A at nt551 among 117 samples was 3.42%, 0%, 0.85%, 95.73%, respectively.

CONCLUSION: In Nanjing and its neighbourhood, hepatitis B patients are mainly infected with wild genotype HBV. The incidence of mutants with a mutation at nt551 in HBV genome is significantly lower than that in wild genotype HBV DNA (P<0.01). The necessity of adding components of HBsAg mutants to HBV vaccine needs further investigation.

Enhancement effect of TNFα on hepatitis B virus in vitro infection of human choriocarcinoma JEGIII cells

AIM: To study the in vitro infection of human choriocarcinoma JEGIII cells by hepatitis B virus (HBV) in the presence of TNF-α, and to provide some clues for the mechanism responsible for HBV intrauterine transmission.

METHODS: Human choriocarcinoma-derived JEGIII cells were exposed to HBV (2×10¹² HBV DNA/L) in the presence of TNF-α. After an overnight incubation, the cells were then trypsinized, extensively washed with PBS till the last washings were negative for HbsAg as identified by ELISA. The cells were re-inoculated and kept on subculturing with fresh medium. Then the specimens were collected at an interval of 12 hours. HBsAg in supernatants and cells was detected by Western blotting, immunohistochemistry and transmission electron microscopy.

RESULTS: After JEGIII cells were infected with HBV for 36 hours, HBsAg was positive in supernatants collected at different time points. The level of HBsAg was significantly higher in JEGIII cells infected by HBV in the presence of TNF-α than that in the absence of TNF-α(20.40±4016 vs 7.40±1.82, P < 0.01). HBsAg was mainly located in the cytolemma and/or the cytoplasm. Under electron microscope, HBsAg particles were observed in the dilated cisterns of rough surfaced endoplasmic reticulum of the cells.

CONCLUSION: Human choriocarcinoma JEGIII cells can be susceptibly infected by HBV in the presence of TNF-α in vitro, and this may provide some clues for further studying HBV intrauterine transmission.

A seroepidemiological Study of Hepatitis B and C Virus (HBV and HCV) Infections in the Young Population in parts of Busan, Korea

OBJECTIVES

To investigate the prevalence of hepatitis B and C virus infections and determine the associated risk factors among young adults in Busan, Korea, which is known to have a high incidence of liver cancer.

METHODS

The study population consisted of volunteer participants in a health survey during 2002, which included 1, 350 students (515 males and 835 females) aged between 16 and 24 years, from three different schools in Busan. The participating students were asked to fill in a selfadministered questionnaire which included lifestyle habits and risk factors of hepatitis. Sera obtained from the participants were studied for HBsAg, anti-HBs, and Anti- HCV by enzyme immunoassay (EIA) method and for liver function tests.

RESULTS

Among the study subjects (N=1, 350), the seropositivities of HBsAg 7.9% (95% CI=7.8-8.0), 7.6% (95% CI=7.6-7.7) in male and 8.1% (95% CI=8.0-8.2) in female. And the seropositivity of Anti-HBs was 69.7% (95% CI=69.0- 70.4), 70.5% (95% CI=69.8-71.2) in male and 69.2% (95% CI=68.5-69.9) in female. The seropositivity of Anti-HCV was 0.4%, 0.2% in male and 0.5% in female. The seropositivity for HBsAg in the subjects not having a hepatitis B vaccination history was twice (95% CI=1.0-4.4) that of those that did. Also, the seropositivity for HBsAg in subjects having experienced sexual intercourse was 1.7 times (95% CI=0.9-3.0) that of the subjects who had not.

CONCLUSIONS

The present study confirmed the high prevalence of HBsAg seropositivity and sexual transmission of HBV among adolescents and young adults may occur. Further studies to evaluate the relationship between HBV vaccination and sexual transmission are required for the young population in Korea.

Chronic hepatitis B infection in Canada

Recent developments in the treatment and prevention of hepatitis B virus (HBV) infections warrant revisiting important epidemiological questions, such as how prevalent is chronic HBV infection in Canada, in which Canadian subpopulations are HBV prevalence rates the highest, in what percentage of infected individuals is the virus actively replicating, and how many infected Canadians are candidates for antiviral therapy? Currently available data suggest the overall prevalence of HBV-infected individuals in the general population is approximately 2%, with 5% to 10% having serological evidence of previous HBV infection. In high risk groups, such as street-connected individuals, Aboriginals and immigrants from endemic areas, these rates of viral prevalence and serological evidence of previous HBV infection are approximately two to 10 and five to 10 times higher, respectively, than in the general population. Candidates for antiviral therapy range from less than 1% of infected Aboriginals to 15% to 30% of Asians with chronic HBV. From these data, it is clear that chronic HBV remains an important public health problem in this country. Hence, resources must be identified to enhance Canadians' awareness of HBV infection, maintain, if not expand, efforts to identify and implement safe and effective antiviral therapy for HBV-infected individuals, and continue programs for universal vaccination to prevent new HBV infections.

Comparative study on proliferation activity in small hepatocellular carcinoma related to hepatitis virus B and C

AIM: To compare the proliferation activity of small hepatocellular carcinoma (HCC) related to hepatitis B virus (HBV) and hepatitis C virus (HCV).

METHODS: Sixty liver biopsy specimens were obtained from patients with small HCC (≤3 cm in diameter) and examined immunohistochemically using anti-proliferating cell nuclear antigen monoclonal antibody. Of the 60 specimens, 30 were HBV-related and 30 were HCV-related. The 60 patients providing the samples for study were matched by sex and morphologic features of the HCC specimens.

RESULTS: The labeling index of proliferating cell nuclear antigen was 7.9% in the HBV-related HCC specimens and 12.5% in the HCV-related HCC specimens. There was no statistically significant difference between the two groups (P > 0.05).

CONCLUSION: In the early phase, or small stage, of HCC, HBV-related HCC shows similar proliferating activity to that of HCV-related HCC; this finding suggests that in the early phase, HBV-related HCC has similar malignancy to HCV-related HCC.

STUDIES ON HBsAG IN HIV SEROPOSITIVE CASES

Two hundred and fifty five patients with human immunodeficiency virus (HIV) infection were screened for hepatitis B virus surface antigen (HBsAg) over a period of 3 years. These patients were followed up every 6 month. 10.2% of HIV seropositive cases revealed presence of HBsAg. It was also observed that almost half (47.6%) of these cases developed carrier state.