Carcinoma, Hepatocellular ; etiology ; DNA, Viral ; metabolism ; Hepatitis B ; complications ; Hepatitis C ; complications ; Humans ; Liver Neoplasms ; etiology ; Trans-Activators ; physiology ; Viral Core Proteins ; physiology ; Viral Nonstructural Proteins ; physiology

OBJECTIVETo study the inhibition effect of HCV NS5A on p53 protein transactivity and its possible mechanism.

METHODSLuciferase reporter gene system was used for the study of p53 transactivity on p21 promoter and electrophorectic mobility-shift assay (EMSA) was applied to observe whether HCV NS5A could suppress the binding ability of p53 protein to its specific DNA sequence.

RESULTSEndogenous p53 protein could stimulate p21 promoter activity, and the relative luciferase activity increased significantly (3.49 x 10(5) vs 0.60 x 10(5), t = 5.92, P<0.01). Exogenous p53 protein also up-regulated p21 promoter driving luciferase expression, comparing to the control group (0.47 x 10(5)), the relative luciferase activity increased (5.63 x 10(5)) obviously (t = 10.12, P<0.01). HCV NS5A protein inhibited both endogenous and exogenous p53 transactivity on p21 promoter in a dose-dependent manner (F > or = 20.71, P<0.01). In the experiment of EMSA, p53 could bind to its specific DNA sequence, but when co-transfected with HCV NS5A expressing vector, the p53 binding affinity to its DNA decreased.

CONCLUSIONHCV NS5A can inhibit p53 protein transactivity on p21 promoter through its inhibiting of p53 binding ability to the specific DNA sequence.

Hepacivirus ; genetics ; Humans ; Promoter Regions, Genetic ; Transcriptional Activation ; drug effects ; Tumor Suppressor Protein p53 ; drug effects ; genetics ; metabolism ; physiology ; Viral Core Proteins ; genetics ; Viral Nonstructural Proteins ; genetics ; pharmacology

OBJECTIVETo study the roles of different truncated hepatitis C virus (HCV) core proteins (CORE) in the pathogenesis of HCV persistent infection and hepatocellular carcinoma (HCC) and to assess intracellular localization in transiently transfected cells.

METHODSSeven truncated GFP (green fluorescent protein)-CORE fusion protein expression plasmids were constructed, which contained HCV CORE sequences derived from tumor tissues (BT) and non-tumor tissues (BNT) from one patient infected with HCV. Amino acid (aa) lengths were BT: 1-172 aa, 1-126 aa, 1-58 aa, 59-126 aa, 127-172 aa; BNT: 1-172 aa and C191: 1-172 aa respectively. Subcellular localization of CORE-GFP was analyzed by con-focal laser scanning microscope. Apoptosis and necrosis were quantified by flow cytometry.

RESULTSDifferent truncated CORE-GFP localized mainly in the cytoplasm, but nuclear staining was also observed. HCV CORE could induce apoptosis and necrosis, and different truncated COREs could induce cell apoptosis and necrosis at different levels. Among the same length 1-172 aa of BT, BNT and C191, the cell apoptosis and necrosis percentage of BT is highest, and C191 is the lowest (BT>BNT>C191). To the different fragment COREs of BT, N-terminal of CORE induced apoptosis and necrosis higher, compared with that of C-terminal (1-172 aa>1-126 aa>1-58 aa>127-172 aa>59-126 aa).

CONCLUSIONThese results suggest HCV CORE could induce apoptosis and necrosis of cells, which might play an important role in the pathogenesis of HCV persistent infection and HCC and the different CORE domains of different HCV quasi-species might have some difference in their pathogenesis.

Apoptosis ; Cell Line, Tumor ; Hepacivirus ; genetics ; pathogenicity ; physiology ; Humans ; Necrosis ; virology ; Sequence Deletion ; genetics ; Viral Core Proteins ; chemistry ; genetics ; metabolism

Adult ; DNA, Viral ; genetics ; Hepatitis B virus ; genetics ; physiology ; Hepatitis B, Chronic ; virology ; Humans ; Liver ; virology ; Male ; Severity of Illness Index ; Viral Core Proteins ; genetics ; Virus Replication

OBJECTIVETo explore the possibility of using HBV as a gene delivery vector, and to test the anti-HBV effects by intracellular combined expression of antisense RNA and dominant negative mutants of core protein.

METHODSFull length of mutant HBV genome, which expresses core-partial P fusion protein and/or antisense RNA, was transfected into HepG2.2.15 cell lines. Positive clones were selected and mixed in respective groups with hygromycin in the culture medium. HBsAg and HBeAg, which exist in the culture medium, were tested by ELISA method. Intracellular HBc related HBV DNA was examined by dot blot hybridization. The existence of recombinant HBV virion in the culture medium was examined by PCR. Free of packaging signal, HBV genome, which express the HBV structural proteins including core, pol and preS/S proteins, was inserted into pCI-neo vector. HepG2 cell lines were employed to transfect with the construct. G418 selection was done at the concentration of 400mug/ml in the culture medium. The G418-resistant clones with the best expression of HBsAg and HBcAg were theoretically considered as packaging cell lines and propagated under the same conditions. It was transfected with plasmid pMEP-CPAS and then selected with G418 and hygromycin in the culture medium. The existence of recombinant HBV virion in the culture medium was examined by PCR.

RESULTSThe mean inhibitory rates of HBsAg were 2.74% 3.83%, 40.08 2.05% (t=35.5, P<0.01), 66.54% 4.45% (t=42.3, P<0.01), and 73.68% 5.07% (t=51.9, P<0.01) in group 2.2.15-pMEP4, 2.2.15-CP, 2.2.15-SAS, and 2.2.15-CPAS, respectively. The mean inhibitory rates of HBeAg were 4.46% 4.25%, 52.86% 1.32% (t=36.2, P<0.01), 26.36% 1.69% (t=22.3, P<0.01), and 59.28% 2.10% (t=39.0, P<0.01), respectively. The inhibitory rates of HBc related HBV DNA were 0, 82.0%, 59.9%, and 96.6%, respectively. Recombinant HB virion was detectable in the culture medium of all the three treatment groups. G418-resistant HBV packaging cell line, which harbored an HBV mutant whose packaging signal had been deleted, was generated. Expression of HBsAg and HBcAg was detectable. Transfected with plasmid pMEP-CPAS, it was found to secrete recombinant HB virion and no wild-type HBV was detectable in the culture medium.

CONCLUSIONSIt has stronger anti-HBV effects by combined expression of antisense RNA and dominant negative mutants than by individual expression of them. With the help of wild-type HBV, the modified HBV genome can form and secret HBV like particles, which provides evidence that the antiviral gene will be hepatotropic expression and the antiviral effects will be amplified. The packaging cell line can provide packaging for replication-defective HBV, but with low efficiency.

Cell Line ; Genetic Engineering ; Genetic Vectors ; Hepatitis B virus ; genetics ; Mutation ; Plasmids ; RNA, Antisense ; physiology ; Transfection ; Viral Core Proteins ; physiology ; Virus Assembly ; Virus Replication

Hepatitis C virus (HCV), one of the major pathogens of viral hepatitis, causes significant hazards in humans. Interferon treatment in combination with ribavirin is used as the first line clinical treatment for HCV infection. However, good response to this treatment has only been observed in few patients and repeated recurrence has also been reported frequently. Therefore, new antiviral agents and therapies are in urgent demand. Here, we report a newly constructed Escherichia coli RNase P based M1GS ribozyme that can specifically and efficiently target the core gene of HCV. The guide sequence (GS) of this M1IGS was designed according to the sequence of the core coding region of HCV genome. The GS was then covalently linked to the 3' terminus of M1 RNA, the catalytic subunit of RNase P from Escherichia coli. The specification of this sequence-specific ribozyme, M1GS, was then examined using an in vitro cleavage assay. The cytotoxicity and its activity in inhibition of HCV gene expression and viral proliferation were further studied in vivo. Our results show that the reconstructed M1GS ribozyme displayed obvious catalytic activity in cleaving target mRNAs fragment in vitro. Notable reduction in the expression of HCV core protein and a 1 000-fold reduction in viral growth were also observed in cultured HCV infected Huh7.5.1 cells expressing the functional M1GS ribozyme. This study demonstrated a direct evidence for the antiviral activity of the customized M1GS-HCV/C141 ribozyme, and thus provided a promising new strategy for clinical treatment of HCV infection.
Antiviral Agents ; pharmacology ; Escherichia coli ; genetics ; Genetic Engineering ; Hepacivirus ; genetics ; physiology ; RNA, Catalytic ; genetics ; pharmacology ; RNA, Guide ; genetics ; Ribonuclease P ; genetics ; Viral Core Proteins ; genetics

OBJECTIVESThe hepatitis B virus core protein has been found in nuclei, cytoplasm, or both of hepatocytes transfected with HBV DNA. It is still unclear whether intact core particles could pass through nuclear pores and what could be the mechanism regulating the subcellular localization of the core protein. This study on the distribution of core protein in hepatocytes and its translocation has a potential advantage to learn more about the HBV life cycle.

METHODSDimethyl sulphoxide (DMSO, 2%), which effects hepatic differentiation, and/or 1 micro mol/L heteroaryldihydropyrimidine Bay41-4109, which interferes with the assembly of core particles, were added into HepG2.2.15 cell culture system for 4 days. The hepatitis B virus core antigen (HBcAg) and hepatitis B virus surface antigen (HBsAg) were stained with fluorescent immunocytochemistry and then observed under a confocal microscope. HBcAg in cytoplasm and nuclei were respectively extracted and analyzed using Western blot. HBV covalently closed circular DNA (cccDNA) was detected by using selective PCR method.

RESULTSThe HBcAg was mostly expressed in the cytoplasm and weak signals of cccDNA were detected in the control HepG2.2.15 cells. After DMSO treatment, the expression of HBcAg in cytoplasm was increased about 2.5-fold; the expression of HBcAg and cccDNA in nuclei also increased. With the use of Bay41-4109, the signal of HBcAg in cytoplasm decreased 2/3, but it increased in the nuclei, and cccDNA decreased in the nuclei. When the HepG2.2.15 cells were treated both with DMSO and Bay41-4109, cord-liked distribution of HBsAg was observed in the cytoplasm. HBcAg in cytoplasm was decreased 1/2 but the HBcAg in the nuclei increased about 5-fold, whereas the cccDNA was almost negative.

CONCLUSIONIn HepG2.2.15 cells, the core protein is mainly assembled as a formation of core particles in the cytoplasm and they are blocked by the nuclear membrane. Bay41-4109 interferes with the assembly of core particles and the dissociated core proteins are able to enter the nuclei. DMSO promotes the nuclear entry of core protein/core particles and facilitates the formation of cccDNA.

Chromosome Positioning ; Dimethyl Sulfoxide ; pharmacology ; Hep G2 Cells ; Hepatitis B Core Antigens ; metabolism ; Hepatitis B virus ; physiology ; Humans ; Neoplasm Metastasis ; Pyridines ; pharmacology ; Pyrimidines ; pharmacology ; Viral Core Proteins ; metabolism ; Virus Assembly

Avian influenza virus subtype H9N2 has been circulating in multiple terrestrial birds and repeatedly infecting mammals, including swines and humans to pose a significant threat to public health. The cross-species infection of human, replication activity and tissue tropism of avian influenza virus H9N2 was evaluated in this study. The results showed that surgically removed human lung tissue samples were infected ex vivo by avian influenza virus subtype H9N2 (Ck/GX/1875/04, Ck/GX/187/05) and seasonal human influenza virus H3N2 (A/ST/602/05). Examination of nucleoprotein expression replication in the infected human lung tissue samples showed that the replication of avian influenza virus H9N2 and seasonal human influenza virus H3N2 were mainly prevalent in alveolar epithelial cells, respiratory bronchiole epithelial cells and bronchial epithelial cells. Double-immunostaining for viral antigens and cellular markers indicated that avian influenza virus subtype H9N2 replicated in type 2 alveolar epithelial cells. These findings suggest that the H9N2 virus may be better adapted to the human host and replicates efficiently in human lung epithelial cells. Moreover, H9N2 avian influenza virus repeatedly infecting human, may favor gene evolution and the potential emergence of pandemic influenza virus.
Animals ; Epithelial Cells ; virology ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; physiology ; Influenza A Virus, H9N2 Subtype ; genetics ; isolation & purification ; physiology ; Influenza, Human ; virology ; Lung ; cytology ; virology ; RNA-Binding Proteins ; genetics ; metabolism ; Viral Core Proteins ; genetics ; metabolism ; Virus Replication

OBJECTIVETo study the effect of hepatitis C virus core protein (HCV-C) on human normal biliary epithelial cells (BEC) transformation and tumor development.

METHODSBEC cells were transfected with plasmid pcDNA HCV-C (expressing HCV-C) by lipofectamine and selected in G418. The expression of HCV-C gene and protein was determined by PCR and immunohistochemical staining, respectively. Biological effect of transfected cells was observed through cell proliferation assay, anchor independent growth, and tumor development in nude mice. The expression of HCV-C protein in the induced tumor was evaluated by immunohistochemistry.

RESULTSHCV-C was strongly expressed in BEC cells transfected with plasmid pcDNA HCV-C and the positive signal was located in cytoplasm. The HCV-C expression protein in the induced cytoplasm. Cell proliferation assay showed that the population doubling time in the pcDNA HCV-C transfected cells was much shorter than that in the pcDNA3 and non-transfected cells (14 h, 28 h, 30 h respectively). The cloning efficiencies of transfected cells with pcDNA HCV-C, pcDNA3 and non-transfected cells were 36%, 2.5% and 1.5%, respectively (P < 0.01). Tumor developed in nude mice inoculated with pcDNA HCV-C transfected cells after the inoculation. HE staining showed bile duct carcinoma character and immunohistochemistry confirmed HCV-C expression in the tumor tissue. The positive control group also showed tumor development, while no tumor mass obtained in the nude mice inoculated with pcDNA3 and non-transfected cells even 36 days after the injection.

CONCLUSIONHCV-C protein showed human normal biliary epithelial cells transformation and tumorigenic features.

Animals ; Bile Duct Neoplasms ; etiology ; Bile Ducts ; cytology ; Cell Transformation, Neoplastic ; Cell Transformation, Viral ; Cells, Cultured ; Epithelial Cells ; pathology ; Female ; Hepacivirus ; Humans ; Mice ; Mice, Nude ; Plasmids ; Transfection ; Viral Core Proteins ; physiology

BACKGROUNDTo explore the possibility of using HBV as a gene delivery vector, and to test the anti-HBV effects by intracellular expression of dominant negative mutants of core protein.

METHODSTwo kinds of full length mutant HBV genome, which express Core-partial P and Core-S fusion protein, were transfected into HepG 2.2.15 cell lines. Positive clones were selected and mixed in respective groups with hygromycin in the culture medium. HBsAg and HBeAg, which exist in the culture medium, were tested by ELISA and intracellular HBc related HBV DNA was examined by dot blot hybridization. The existence of recombinant HBV virion in the culture medium was examined by PCR.

RESULTSThe mean inhibitory rates of HBsAg were 2.74+/-3.83%, 40.08+/-2.05% (P less than 0.01) and 52.94+/-1.93% (P less than 0.01) in group 2.2.15-pMEP4, 2.2.15-CP and 2.2.15-CS, respectively. The mean inhibitory rates of HBeAg were 4.46+/-4.25%, 52.86+/-1.32% (P less than 0.01) and 41.60+/-1.65% (P less than 0.01), respectively. The inhibitory rates of HBc related HBV DNA were 15.3%, 82.0% and 67.2%, respectively. Recombinant HBV virion was detectable in the culture medium of only group 2.2.15-CP.

CONCLUSIONDominant negative mutants of core protein can efficiently suppress wt-HBV replication and the expressions of HBV antigens. With the help of wild-type HBV, the recombinant HBV genome can form and secret HBV like particles, which provides evidence that the antiviral gene will be hepatotropic expression and the antiviral effects will be amplified.

Cell Line, Tumor ; Genetic Engineering ; Genetic Therapy ; Genetic Vectors ; Genome, Viral ; Hepatitis B Core Antigens ; biosynthesis ; physiology ; Hepatitis B virus ; genetics ; Humans ; Point Mutation ; Recombinant Fusion Proteins ; biosynthesis ; physiology ; Virus Replication