OBJECTIVETo investigate the biological role of auto-induced expression of hepatitis C virus (HCV) core protein (protein C) using a recombinant protein in an in vitro cell-based system.

METHODSThe PCR-amplified full-length HCV protein C gene (573 bp) was inserted into the pET28a prokaryotic expression vector. The recombinant plasmid was transformed into BL21(DE3)pLysS E. coli to achieve high-concentration expression of the recombinant C protein by auto-induction. The recombinant protein C was purified by Ni-NTA affinity chromatography, and tested in a protein binding assay for its ability to bind the HCV NS3 protein.

RESULTSThe transformed E. coli produced a large amount of recombinant protein C, as detected in the sonicated supernatant of the bacteria culture. The antigenic reactivity of the recombinant protein C was confirmed by western blotting. However, the recombinant protein C could not be purified by Ni-NTA affinity chromatography, but co-precipitated with the HCV NS3 protein.

CONCLUSIONSoluble recombinant protein C was successfully expressed by auto-induction, and shown to interact with the HCV NS3 protein, which provides a novel insight into the putative biological activity of this factor in HCV-related molecular processes. Future studies of this recombinant HCV protein C's crystal structure and antigenicity may provide further clues to its biological function(s) and potential for clinical applications.

Escherichia coli ; metabolism ; Genetic Vectors ; Hepacivirus ; Recombinant Proteins ; genetics ; metabolism ; Viral Core Proteins ; biosynthesis ; genetics ; metabolism ; Viral Nonstructural Proteins ; metabolism

OBJECTIVETo investigate the effects of the hepatitis B virus (HBV) P22e protein on the apoptosis of human hepatocellular carcinoma HepG2 cells.

METHODSHepG2 cells were transfected with recombinant plasmid pEGFP-HBVP22e and exposed to Act-D and tumor necrosis factor alpha (TNFalpha) treatment to induce cell apoptosis. Flow cytometry was performed to determine the proportion of cells containing sub-G1 DNA to represent the number of apoptotic cells. Laser scanning confocal microscopy was used to observe the nuclear alterations in the apoptotic cells.

RESULTSHepG2EGFP-C2HBVP22e cell strain showed a much delayed apoptosis as well as obviously lowered apoptotic rate in comparison with the HepG2 strain (P<0.01).

CONCLUSIONThe introduction and expression of extraneous gene HBVP22e significantly inhibits the apoptosis of HepG2 cells.

Apoptosis ; Carcinoma, Hepatocellular ; metabolism ; Hep G2 Cells ; Hepatitis B Core Antigens ; metabolism ; Humans ; Transfection ; Viral Core Proteins ; metabolism

OBJECTIVETo screen cellular proteins binding to the core region of hepatitis C virus (HCV) from human hepatoma cells.

METHODSUnlabeled and labeled RNA transcripts were prepared by in vitro transcription. Cytoplasmic extracts were prepared from human hepatoma cells HepG2. Ultraviolet (UV) cross-linking was used to screen the cellular proteins that would bind to the core region of HCV. Competition experiment was performed to confirm the specificity of the binding in which excess unlabeled RNA of HCV core region and plasmid RNA were used as competitors.

RESULTSTwo cellular proteins of 6.6 x 10(4) and 5.5 x 10(4) were found binding to the core region of HCV RNA by UV cross-linking assay. The unlabeled core region of HCV RNA could compete out this binding whereas the unlabeled plasmid RNA could not.

CONCLUSIONThe cellular proteins from HepG2 cells could bind to the core region of HCV RNA.

Binding Sites ; Cross-Linking Reagents ; chemistry ; Hepacivirus ; genetics ; metabolism ; RNA, Viral ; genetics ; metabolism ; Ultraviolet Rays ; Viral Core Proteins ; genetics ; metabolism

BACKGROUNDTo study the significance of the expression of HCV core protein in PBMC of patients with chronic hepatitis C and to evaluate the relationship between HCV core protein expression and clinical states.

METHODSIdentification of HCV protein antigen (Ag) in PBMC of 66 hepatitis C patients by immunohistochemical method and clinical status of the patients with HCV protein positive expression were investigated. In 27 out off 66 patients the HCV RNA and HCV Ag in PBMC were detected with RT-PCR and immunohistochemical method.

RESULTSThe HCV Ag (core+NS3) was identified in PBMC in 51 out of 66 patients (77.27%). It was also demonstrated that HCV core protein in nucleus showed strong expression and NS3 protein in cytoplasm showed weak expression. The expression of core protein in nucleus of PBMC were 35.29% in advanced chronic hepatitis patients, which was significantly higher than that from moderate cases (5.88%).

CONCLUSIONSThis study suggested that the expression of PMBC-HCV core protein may be related to the clinical state of the patients. The nuclear expression of HCV core protein in PBMC of patients with hepatitis C may be related to the persistence and activity of the chronic hepatitis C virus and play an important role in the pathogenesis of cirrhrosis and hepatocellular carcinoma.

Hepatitis C Antigens ; blood ; Hepatitis C, Chronic ; virology ; Humans ; Immunohistochemistry ; Leukocytes, Mononuclear ; metabolism ; RNA, Viral ; blood ; Viral Core Proteins ; blood

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 clone the gene encoding nucleocapsid protein (NP) of hantavirus strain Z10 (HV-Z10), to construct its prokaryotic expression system as well as to establish a rNP-IgM direct capture ELISA based on HRP-labeled recombinant NP (rNP), in order to detect serum samples of patients suffering from hemorrhagic fever with renal syndrome (HFRS) and to evaluate the effects of detection.

METHODSGene encoding NP of strain HV-Z10 was amplified by PCR and then its prokaryotic expression system pET28a-Z10N-E. coli BL21DE3 was constructed, using routine genetic engineering method. SDS-PAGE was applied to measure the expression of rNP and ion-exchange plus Ni-NTA-affinity chromatography was performed to purify the recombinant product. Western blot assay was used to determine the specific immuno-reactivity of rNP while HRP-labeled rNP-IgM direct capture ELISA was established to detect the serum samples from 95 cases of confirmed HFRS patients. The detection effect was compared with that by routine HV-IgM indirect capture ELISA method.

RESULTSpET28a-Z10N-E. coli BL21DE3 was able to express rNP with high efficiency. The purified rNP only showed a single protein fragment in the gel after SDS-PAGE. HV-IgG could efficiently recognize rNP and hybridize with the recombinant protein. 94.73% (90/95) of HFRS patients' serum samples were positively confirmed by rNP-IgM direct capture ELISA, while a positive rate of 92.63% (88/95) in the same samples was confirmed by HV-IgM indirect capture ELISA. The distributions of A450 values of the serum samples detected by the two IgM capture ELISAs as well as the changes of the A450 mean values from several serum samples with different dilutions were similar.

CONCLUSIONWe successfully constructed a high efficient prokaryotic expression system of NP encoding gene of hantavirus strain HV-Z10. The rNP-IgM direct capture ELISA that established in this study could be used as a new serological test for HFRS diagnosis because of its simplicity, safety, with high sensitivity and specificity.

Blotting, Western ; Capsid Proteins ; genetics ; immunology ; metabolism ; Enzyme-Linked Immunosorbent Assay ; methods ; Humans ; Immunoglobulin M ; immunology ; Recombinant Proteins ; genetics ; immunology ; metabolism ; Viral Core Proteins ; genetics ; immunology ; metabolism

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

OBJECTIVETo identify HCV core protein binding proteins.

METHODSThe library was amplified, purified, and then were transformed into yeast strain Y187. The reconstructed plasmid pGBKT7-core was transformed into yeast strain AH109 and screened on the nutrient deficiency medium SD/-Trp. The transformed AH109 mated with Y187 containing the library plasmid. The diploid yeast cells were plated on nutrient deficiency medium SD/-Trp/-Leu/-His/-Ade and SD/-Trp/-Leu/-His/-Ade containing X-alpha-gal for selecting. The plasmids in diploid yeast cells were extracted and electrotransformed into E.coli DH5alpha. The plasmids in DH5alpha were extracted and sequenced.

RESULTSEleven proteins, including chymotrypsinogen B1 precursor, carboxypeptidase A1, trypsinogen 2, chymotryptic peptide C, trypsin 1, carboxypeptidase B1, kinesin superfamily proteins 3B, trypsin 2, mitochondria protein gene, elastase 3A and colipase were found to be able to bind to HCV core protein.

CONCLUSIONSProteins related with metabolism of glucose and lipid may bind to HCV core protein.

Gene Library ; Hepacivirus ; genetics ; Plasmids ; genetics ; Polymerase Chain Reaction ; Transformation, Genetic ; Two-Hybrid System Techniques ; Viral Core Proteins ; genetics ; metabolism

The core protein (CP) of the classical swine fever virus (CSFV) is one of its structural proteins. Apart from forming the nucleocapsid to protect internal viral genomic RNA, this protein is involved in transcriptional regulation. Also, during viral infection, the CP is involved in interactions with many host proteins. In this review, we combine study of this protein with its disorders, structural/functional characteristics, as well as its interactions with the non-structural proteins NS3, NS5B and host proteins such as SUMO-1, UBC9, OS9 and IQGAP1. We also summarize the important part played by the CP in CSFV pathogenicity, virulence and replication of genomic RNA. We also provide guidelines for further studies in the CP of the CSFV.
Animals ; Classical Swine Fever ; virology ; Classical swine fever virus ; genetics ; metabolism ; pathogenicity ; Genome, Viral ; Swine ; Viral Core Proteins ; chemistry ; genetics ; metabolism ; Virulence