DNA sequences homologous to hepatitis C virus (HCV) in the extrachromosomal circular DNA in peripheral blood mononuclear cells of HCV-negative subjects.

OBJECTIVE: This study aimed to investigate DNA sequences that are substantially homologous to the corresponding RNA sequence sections of the hepatitis C virus (HCV). These DNA sequences are present in the whole DNA extracted from peripheral blood mononuclear cells (PBMCs) of HCV-negative subjects. We presumed that these experimentally proven 5'-noncoding region (5'-NCR) homologous DNA sequences could be contained in the extrachromosomal circular DNA (eccDNA) fraction as part of the whole cellular DNA. METHODS: Home-made polymerase chain reaction (PCR) with whole cellular and isolated eccDNA, nucleotide basic local alignment search tool (BLASTn) alignments, and tests for patterns of methylation in selected sequence sections were performed. RESULTS: The PCR tests revealed DNA sequences of up to 320 bp that broadly matched the corresponding sequence sections of known HCV genotypes. In contrast, BLASTn alignment searches of published HCV 5'-NCR sequences with human genome databases revealed only sequence segments of up to 36 bp of the 5'-NCR. The composition of these sequences shows missing base pairs, base pair mismatches as well as complete homology with HCV reference sequences. These short sequence sections are present in numerous copies on both the same and different chromosomes. The selected sequence region within the DNA sequences of the 5'-NCR revealed a broad diversity of individual patterns of methylation. CONCLUSIONS: The experimental results confirm our assumption that parts of the HCV 5'-NCR genomic RNA sequences are present at the DNA level in the eccDNA fraction of PBMCs. The tests for methylation patterns therein revealed individual methylomes which could represent an epigenetic feature. The respective sequence section might be subject to genetic regulation.

Expression of H5N1 influenza virus hemagglutinin protein fused with protein transduction domain in an alphavirus replicon system.

Alphavirus replicons, in which structural protein genes are replaced by heterologous genes, express high levels of the heterologous proteins. On the basis of the potencies of replicons to self-replicate and express foreign proteins and the remarkable intercellular transport property of VP22, a novel alphavirus Semliki Forest virus (SFV) replicon system of VP22 fused with a model antigen, hemagglutinin (HA), of the human-avian H5N1 influenza virus, was explored in this study. Further, replicon particles expressing HA, VP22, and enhanced green fluorescent protein (EGFP) individually were used as controls. By flow cytometry based on the analysis of transfection efficiency, SFV-EGFP replicon particle titer was 1.13 x 10(7)transducing units (TU)/ml. The titers of SFV-HA, SFV-VP22 and SFV-VP22-HA replicon particles, which were titrated by using SFV-EGFP replicon particles, were 1.42 x 10(7), 3.23 x 10(7), and 1.01 x 10(7)TU/ml, respectively. HA and VP22-HA expression was observed in SFV-HA- and SFV-VP22-HA-transfected BHK-21 cells, respectively. Immunofluorescence staining revealed that the fluorescence intensity in the SFV-VP22-HA-transfected BHK-21 cells was more than that in the SFV-HA-transfected BHK-21 cells. Both SFV-VP22-HA and SFV-HA replicon particles presented a promising approach for developing vaccines against human-avian influenza. VP22-HA fusion protein with similar trafficking properties may also enhance vaccine potency.

Construction and cellular immune response induction of HA-based alphavirus replicon vaccines against human-avian influenza (H5N1).

Several approaches are being taken worldwide to develop vaccines against H5N1 viruses; most of them, however, pose both practical and immunological challenges. One potential strategy for improving the immunogenicity of vaccines involves the use of alphavirus replicons and VP22, a herpes simplex type 1 (HSV-1) protein. In this study, we analysed the antigenic peptides and homogeneity of the HA sequences (human isolates of the H5N1 subtype, from 1997 to 2003) and explored a novel alphavirus replicon system of VP22 fused with HA, to assess whether the immunogenicity of an HA-based replicon vaccine could be induced and augmented via fusion with VP22. Further, replicon particles expressing VP22, and enhanced green fluorescent protein (EGFP) were individually used as controls. Cellular immune responses in mice immunised with replicons were evaluated by identifying specific intracellular cytokine production with flow cytometry (FCM). Animal-based experimentation indicated that both the IL-4 expression of CD4(+) T cells and the IFN-gamma expression of CD8(+) T cells were significantly increased in mice immunised with VPR-HA and VPR-VP22/HA. A dose titration effect vis-à-vis both IL-4 expression and IFN-gamma expression were observed in VPR-HA- and VPR-VP22/HA-vaccinated mice. Our results revealed that both VPR-VP22/HA and VPR-HA replicon particles presented a promising approach for developing vaccines against human-avian influenza, and VP22 could enhance the immunogenicity of the HA antigens to which it is fused.

Influence of HBV gene heterogeneity on the failure of immunization with HBV vaccines in eastern China.

The influence of hepatitis B virus (HBV) gene heterogeneity on the failure of HBV vaccination in eastern China remains unknown. Here, we assigned 78 hepatitis B surface antigen (HBsAg)-carrier mothers to two groups: 41 mothers from whom transmission of HBV to their children was successfully prevented and 37 mothers whose children were HBsAg positive 1 year after HBV vaccination. The DNA loads in mothers of the failure group (4.17E + 07 copies/ml) were significantly higher than those in the success group (8.40E + 06 copies/ml). However, no difference was found in the S gene mutation rate and genotypes between the groups. Interestingly, Thr123Ala and Gly145Arg were observed only in failure-group mothers, whereas Thr126Asn, Thr126Ser, Thr143Asn, Asp144Gly, and Asp144Ala were seen in the success group. Thus, high viral load is an important risk factor for HBV vaccination failure, which is correlated with the positions of mutations in the S gene, but not with mutant frequencies or genotypes.

[Cleavage of in vitro transcripts of hepatitis B virus C gene by 10-23 DNA enzyme].

OBJECTIVE: To investigate the cleavage activities of 10-23 DNA enzymes targeting at HBV C gene mRNA in vitro. METHODS: 10-23 DNA enzymes named DrzBC-7, DrzBC-8 and DrzBC-9 specific to HBV C gene ORF A1816UG were designed and synthesized. HBV C gene mRNA was obtained by in vitro transcription method. Cleavage activities were observed in vitro. The influence of MgCl2 concentration on RNA cleaving activity was examined with DrzBC-9. Values of kinetic parameters including Km, Kcat and Kcat/Km were calculated accordingly. RESULT: Targeted substrate mRNA with the size of 300 nt was obtained by transcription in vitro. Under the certain cleavage conditions, DrzBC-7, DrzBC-8 and DrzBC-9 all efficiently cleaved target mRNA at specific sites in vitro. Cleavage products of 109 nt and 191 nt were obtained. No cleavage occurred without MgCl2. The most efficient cleavage was obtained at 150 mmol x L(-1) MgCl2. The efficiency of cleavage did not increase when the MgCl2 concentration was more than 200 mmol x L(-1). The kinetic parameters, Km, Kcat and Kcat/Km for DrzBC-9 were 1.4x10(-9) mol x L(-1), 1.6 min(-1) and 1.1x10(9) mol x L(-1) x min(-1), respectively. CONCLUSION: 10-23 DNA enzymes targeting at HBV C gene mRNA possess the specific cleavage activities in vitro.

[Inhibition of hepatitis B virus S gene and C gene expression by different 10-23 DNAzymes substrate-recognition domains].

OBJECTIVE: To explore the inhibition effects of 10-23 DNAzymes with different substrate-recognition domains targeting hepatitis B virus (HBV) S gene and C gene expression in 2.2.15 cells. METHODS: 10-23 DNAzymes with different substrate-recognition domains specific to HBV S gene open reading frame (ORF) A(157)UG and HBV C gene ORF A(1816)UG were designed and synthesized, respectively. Different 10-23 DNAzymes were transfected into 2.2.15 cells which is a stable HBV producing cell line. HBsAg and HBeAg secreted into culture media were detected by radioimmunoassay (RIA) and HBV DNA levels were measured by real-time PCR. 3-(4, 5-dimethylthiagol-2-yl)-2, 5-drphnyl tetrazolium bromide (MTT) assays were performed to evaluate cytotoxicity. RESULTS: HBsAg and HBeAg expressions were reduced by various DNAzymes (0.1 - 2.5 micromol/L) with different substrate-recognition domains after transfection. The antiviral effects of DNAzymes were apparent until 72 h post-transfection. The inhibition rates of the DNAzymes at the same dose on HBsAg and HBeAg in the same period of post-transfection were as the following: DrzBS-9 > DrzBS-8 > DrzBS-7; DrzBC-9 > DrzBC-8 > DrzBC-7. Among all the DNAzymes used, DrzBS-9 targeting S gene and DrzBC-9 targeting C gene were most potent, with HBsAg and HBeAg reduced 95% and 92% 48 h post-transfection at the dose of 2.5 micromol/L, respectively. The inhibition effects on HBV DNA by various DNAzymes with different substrate-recognition domains were of no significance. There were no evident cytotoxic effects of these DNAzymes in the range from 0.1 to 2.5 micromol/L. CONCLUSION: 10-23 DNAzymes with different substrate-recognition domains targeting HBV S gene and C gene mRNA possessed specific inhibition effects in 2.2.15 cells, and DrzBS-9 targeting S gene and DrzBC-9 targeting C gene were most potent.

In vitro cleavage of hepatitis B virus C mRNA by 10-23 DNA enzyme.

BACKGROUND: 10-23 DNA enzyme is one kind of deoxyribozymes for RNA cleavage. The inhibition effects of 10-23 DNA enzyme on the expression of the HBV C gene in HepG2.2.15 cells were demonstrated previously. The aim of this study was to further explore the cleavage activities of 10-23 DNA enzyme targeting at HBV C gene mRNA in vitro. METHODS: 10-23 DNA enzyme named Drz-HBV-C-9 specific to HBV C gene ORF A(1816)UG was designed and synthesized. HBV C gene mRNA was obtained by the in vitro transcription method. Cleavage activities of Drz-HBV-C-9 were observed in vitro. Values of kinetic parameters including Km,Kcat and Kcat/Km were calculated accordingly. RESULTS: Under the certain cleavage conditions, Drz-HBV-C-9 could efficiently cleave target mRNA at specific sites in vitro. Cleavage products of 109nt plus 191nt were obtained. The kinetic parameters, Km, Kcat and Kcat/Km for Drz-HBV-C-9, were 1.4 X 10(-9) mol, 1.6 min-1 and 1.1 X 10(9) mol(-1) x min(-1), respectively. CONCLUSIONS: 10-23 DNA enzyme targeting at HBV C gene mRNA possesses specific cleavage activities in vitro. This would be a potent antiviral strategy with respect to HBV gene therapy.

Effect of IFNalpha-2a on Fas expression and apoptosis rate of peripheral blood cytotoxic T cells in patients with hepatitis B.

BACKGROUND: Interferon(IFN) with antiviral and immunomodulatory activities is one of the most important therapeutic agents for the treatment of chronic hepatitis. The apoptotic effect of IFN is influenced by cell type and the types of IFN, which suppresses proliferation and induces apoptosis in some cell types while inhibiting apoptosis in others. The aim of this study was to explore the effect of IFNalpha-2a on Fas expression and the apoptosis rate of peripheral blood cytotoxic T cells(CTLs) in patients with hepatitis B. METHODS: Peripheral blood mononuclear cells were isolated from 26 patients with hepatitis B including 16 patients with chronic hepatitis B and 10 patients with chronic severe hepatitis B. Fas expression and apoptosis rate of CTLs were analyzed with flow cytometry before and after IFNalpha-2a treatment. RESULTS: Before IFNalpha-2a treatment, Fas expression and apoptosis rate of CTLs from patients with chronic hepatitis B were significantly higher than those from patients with chronic severe hepatitis B and healthy controls respectively. No significant difference was observed between Fas expression and apoptosis rate of CTLs from patients with chronic severe hepatitis B and healthy controls. After IFNalpha-2a treatment, Fas expression and apoptosis rate of CTLs from different groups were compared with those before IFNalpha-2a treatment, showing no significant difference despite alternation of different degree. CONCLUSIONS: Activation induced cell death (AICD) exists in peripheral blood CTLs from patients with hepatitis B. No effect of IFNalpha-2a exerts on Fas expression and apoptosis rate of Fas in patients with hepatitis B.

Effective inhibition of expression of hepatitis B virus genes by DNAzymes.

AIM: To evaluate the inhibitory effects of DNAzymes on the expressions of hepatitis B virus (HBV) s (HBsAg) and e (HBeAg) in 2.2.15 cells, and to explore the potential therapeutic effects of DNAzymes on replication of HBV genome. METHODS: DNAzymes DrzBS and DrzBC specific to HBV (ayw subtype) s gene ORF A157UG and e gene ORF A1816UG, were designed and synthesized. Inhibitory effects of DrzBS or DrzBC on the expressions of HBV s and e genes as well as HBV DNA levels in culture supernatants were observed in 2.2.15 cells. RESULTS: After being treated with DrzBS or DrzBC, the expression of HBV s or e genes in 2.2.15 cells was depressed dramatically. The maximum inhibition rate was 94.2% and 91.8% for DrzBS and DrzBC, respectively. The concentration for effective inhibition of both DrzBS and DrzBC was within 0.1-2.5 micromol/L, showing a dose-dependence. The efficiency of inhibiting HBsAg, HBeAg in 2.2.15 cells by DrzBS or DrzBC was higher than that of the same target genes by antisense oligonucleotides (ASON). The concentration for effective inhibition of DNAzymes was at least 10-fold lower compared with ASON controls. Neither inhibition on the replication of HBV DNA nor toxicity to 2.2.15 cells was observed. CONCLUSION: DrzBS and DrzBC can block the expression of HBV s- and e-genes in 2.2.15 cells and provide a specific and effective anti-HBV gene therapeutic means.

Character of HBV (hepatitis B virus) polymerase gene rtM204V/I and rtL180M mutation in patients with lamivudine resistance.

OBJECTIVES: To investigate the relationship between HBV (hepatitis B virus) polymerase gene 180 and 204 sites mutation and lamivudine resistance. METHODS: One hundred forty-one patients with lamivudine resistance after lamivudine treatment and 60 chronic hepatitis B patients without lamivudine treatment were enrolled in this study. The serum HBV DNA mutation was analyzed by sequence detection via polymerase chain reaction (PCR). The sequences of the same patient were analyzed before and after lamivudine treatment. RESULTS: One hundred and nine lamivudine resistance patients had HBV YMDD (tyrosine-methionine-aspartate-aspartate) mutation. Among them, 45 patients had rtL180M/M204V mutation (41.28%), 28 patients had rtL180M/M204I mutation (25.70%) and 36 patients had rtM204I mutation (33.02%). There were 6 patients with rtL180M mutation in 32 lamivudine resistance patients. Sixty chronic hepatitis patients without lamivudine treatment had no mutations. CONCLUSIONS: HBV mutations, which play an important role in lamivudine resistance usually locate at polymerase gene 204 site; 180 site mutation was also observed in these patients. Evaluation of the anti-virus therapy by surveillance of the two sites mutations is of importance.

[Detection and analysis of the new kind of G743C and G743A point mutation of HBV P gene in hepatitis B virus infected patients resistant to lamivudine].

OBJECTIVE: To explore the point mutation in hepatitis B virus polymerase (HBV P) gene in HBV-infected patients resistant to lamivudine. METHODS: HBV P gene was amplified by PCR and the products was sequenced to analyze the YMDD mutation. Then the variants were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with the following restriction enzymes: Fok I, Ssp I, Alw441 and were separated by 8.0% polyacrylamide gel electrophoresis. RESULTS: Comparing with the sequences of standard HBV genome, there were 16 patients with G743C mutation and 1 patient with G743A mutation, and the codon ATG turned to ATC and ATA, YMDD motif changed into YIDD. But this kind of YIDD mutation was not proved by PCR-RFLP assay in the 17 patients. CONCLUSIONS: The G743C and G743A mutations in HBV P gene, resulting in YMDD motif changed into YIDD, are detected only by direct sequencing, not by PCR-RFLP. The new kind of G743C and G743A point mutations in HBV P gene is important for the detection of HBV P gene YMDD mutation.

[DNAzymes in vitro inhibit the expression of hepatitis B virus genes].

OBJECTIVE: To evaluate the inhibition effects of DNAzymes specific to Hepatitis B Virus(HBV) s gene and e gene on the expressions of Hepatitis B surface antigen(HBsAg) and Hepatitis B e antigen(HBeAg). METHODS: DNAzymes DrzBS and DrzBC specific to HBV s gene ORF A157UG and e gene ORF A1816UG, respectively, were designed and synthesized. The inhibition effects of DrzBS or DrzBC on the expressions of HBV s and e genes were observed in 2.2.15 cells. RESULTS: The expression of HBV s or e genes was dramatically depressed after 2.2.15 cells treated by DrzBS or DrzBC. The concentration for effective inhibition was within 0.1-2.5 micromol/L and the inhibition showed a dose dependence within that concentration range. The maximum inhibition was 94.2% and 91.8% for DrzBS and DrzBC, respectively. The inhibition was maintained for 72 hours. The efficiency of inhibiting HbsAg, HbeAg in 2.2.15 cells by DrzBS, DrzBC was higher than that by antisense oligonucleotides for the same target genes. The concentrations for effective inhibition of the DNAzymes were at least 10-fold lower compared with antisense oligonucleotides. Neither inhibition on the replication of HBV DNA nor toxicity to 2.2.15 cells was observed. CONCLUSION: DrzBS and DrzBC can highly block the expressions of HBV s gene and e gene in 2.2.15 HBV cell model and are proved a specific and effective anti-HBV gene therapeutic means.

[Influence of HGV super-infected with HIV or HCV on the virus replication].

OBJECTIVE: To realize human immunodeficiency virus(HIV) and hepatitis C virus(HCV) super-infected with hepatitis G virus(HGV or GBV/C) and to probe into the mechanism of these virus infection in the body. METHODS: HIV and HCV load were tested by the quantitated RT-PCR in the HIV or HCV infected plasma samples respectively and the HGV RNA was detected in all of the samples. Then some of the HGV positive were sequenced. RESULTS: 123 of 317 HIV patients were positive for HGV, the positive rate was 38.8%. Among the 91 HCV patients, 19 were positive for HGV. The positive rate is 20.9% which was less than that of HIV patients. HIV load of the patients super-infected with HGV was less than that of those without HGV[(1.8+/-0.6)x10 copies/ml compared with (1.9+/-1.1)x10(2)copies/ml]; while HGV and HCV super-infection did not influence the HCV RNA load significantly [(1.5+/-0.6)x10(4) copies/ml compared with (5.4+/-1.8)x10(4)copies/ml]. The HGV sequences from HIV or HCV patients were compared and showed no difference markedly. CONCLUSION: The rate of the HIV and HGV super-infection is higher than that of HCV. HGV may inhibit HIV reproduction in the body while superinfection.

Mutations in precore and core promoter region of HBV in patients with hepatic failure.

OBJECTIVE: To clarify the association of hepatitis B virus mutants in precore and core promoter regions in patients with hepatic failure and HBeAg state. METHODS: Precore and core promoter regions of 25 HBV isolates from the patients with hepatic failure were analyzed by polymerase chain reaction (PCR) direct sequencing approach. RESULTS: Precore G-to-A(1896) mutants were identified in 16 (64%) of the 25 isolates. The "hot spot" mutations at A-to-T(1762) and G-to-A(1764) were present together in 19 (76%) of the 25 isolates, while C-to-T(1653) and T-to-C(1753) existed in a mutually exclusive manner and more frequently in hepatic failure with liver cirrhosis group than in hepatic failure with chronic hepatitis group (100% vs 50%). Both A(1896) and T(1762)-A(1764) could be found frequently in HBeAg-positive subjects (77.8% and 88.9%), whereas T(1653)/C(1753) was more prevalent in anti-HBe-positive subjects than in HBeAg-positive subjects (93.8% vs 33.3%). CONCLUSIONS: The whole frequency of mutations in precore and core promoter gene will become more frequent as HBV infection is to be persistent. Mutation to T(1653)/C(1753) may be useful as a marker for hepatic failure. It requires further study whether the mixed infection of mutants and wilds will develop and affect the condition of HBeAg in serum along the progression of liver disease.