In vitro neutralization of HCV by goat antibodies against peptides encompassing regions downstream of HVR-1 of E2 glycoprotein

This article aims at testing several in vitro systems with various viral sources and cell lines for propagation of HCV to evaluate goat antibodies raised against three E2 epitopes in viral neutralization experiments. Four human cell lines (Huh-7, Huh-7.5, HepG2, and CaCo2) were tested using two different HCV viral sources; Genotype 4 infected sera and J6/JFH HCV cc particles. Neutralization capacity of goat Abs against conserved E2 epitopes; p412 (a.a 412-419), p517 (a.a 517-531), and p430 (a.a 430-447) were examined in the above mentioned in vitro systems. Although infection with patients' sera seems to mimic the in vitro situation, it has limited replication rates as compared with HCV cc particularly in Huh7.5 cells. Non-HCV adapted Huh-7 cells were also found susceptible for transfection with J6/JFH virus but at much slower kinetics. The results of the neutralization assay showed that anti p412 and anti p517 were highly neutralizing to HCVcc. Our data demonstrate that antibodies directed against the viral surface glycoprotein E2 reduced the infectivity of the J6/JFH virus and are promising agents for immunotherapy and HCV vaccine development.

An overview: in vitro models of HCV replication in different cell cultures

Although much of productive research has been conducted in the field of molecular virology of Hepatitis C virus (HCV) regarding its genes, gene functions and proteins, development of an efficient cell culture model for its replication remained a focused area. Focus has been directed to establish HCV in vitro replication system. This replication system should mimic its intrahepatic pathogenesis so that antivirals should be screened and in vitro gene profiling of HCV induced pathogenesis should be worked out. Since 1990 various experimental approaches and strategies have been utilized in phase of development of a robust replication model for HCV, and success has been reported for a few genotypes. Still the work is going on to have more success in availing such robust replication models for all the genotypes. This will help to have a common antiviral strategy against HCV induced pathogenesis involving any genotype or subtype.

Neutralizing activities of caprine antibodies towards conserved regions of the HCV envelope glycoprotein E2

Anti HCV vaccine is not currently available and the present antiviral therapies fail to cure approximately half of the treated HCV patients. This study was designed to assess the immunogenic properties of genetically conserved peptides derived from the C-terminal region of HVR-1 and test their neutralizing activities in a step towards developing therapeutic and/or prophylactic immunogens against HCV infection. Antibodies were generated by vaccination of goats with synthetic peptides derived from HCV E2. Viral neutralizing capacity of the generated anti E2 antibodies was tested using in vitro assays. Goats immunized with E2 synthetic peptides termed p412 [a.a 412-419], p430 [a.a 430-447] and p517 [a.a 517-531] generated high titers of antibody responses 2 to 4.5 fold higher than comparable titers of antibodies to the same epitopes in chronic HCV patients. In post infection experiments of native HCV into cultured Huh7.5 cells anti p412 and anti p 517 were proven to be neutralizing to HCV genotype 4a from patients' sera (87.5% and 75% respectively). On the contrary anti p430 exhibited weak viral neutralization capacity on the same samples (31.25%). Furthermore Ab mixes containing anti p430 exhibited reduced viral neutralization properties. From these experiments one could predict that neutralization by Abs towards different E2-epitopes varies considerably and success in the enrichment of neutralization epitope-specific antibodies may be accompanied by favorable results in combating HCV infection. Also, E2 conserved peptides p517 and p412 represent potential components of a candidate peptide vaccine against HCV infection.

Neutralizing activities of caprine antibodies towards conserved regions of the HCV envelope glycoprotein E2

Anti HCV vaccine is not currently available and the present antiviral therapies fail to cure approximately half of the treated HCV patients. This study was designed to assess the immunogenic properties of genetically conserved peptides derived from the C-terminal region of HVR-1 and test their neutralizing activities in a step towards developing therapeutic and/or prophylactic immunogens against HCV infection. Antibodies were generated by vaccination of goats with synthetic peptides derived from HCV E2. Viral neutralizing capacity of the generated anti E2 antibodies was tested using in vitro assays. Goats immunized with E2 synthetic peptides termed p412 [a.a 412-419], p430 [a.a 430-447] and p517 [a.a 517-531] generated high titers of antibody responses 2 to 4.5 fold higher than comparable titers of antibodies to the same epitopes in chronic HCV patients. In post infection experiments of native HCV into cultured Huh7.5 cells anti p412 and anti p 517 were proven to be neutralizing to HCV genotype 4a from patients' sera (87.5% and 75% respectively). On the contrary anti p430 exhibited weak viral neutralization capacity on the same samples (31.25%). Furthermore Ab mixes containing anti p430 exhibited reduced viral neutralization properties. From these experiments one could predict that neutralization by Abs towards different E2-epitopes varies considerably and success in the enrichment of neutralization epitope-specific antibodies may be accompanied by favorable results in combating HCV infection. Also, E2 conserved peptides p517 and p412 represent potential components of a candidate peptide vaccine against HCV infection.

A novel immunocompetent rat model of HCV infection and hepatitis

BACKGROUND & AIMS

Hepatitis C virus (HCV) infects millions of people worldwide. Therapy is limited, and treatment does not produce a sustained response in the majority of patients. Development of new agents has been hampered by the lack of a convenient animal model. The aim of this study was to determine whether an immunocompetent rat, tolerized and transplanted with a human hepatoma cell line (Huh 7 cells), could be used to sustain an HCV infection.

METHODS

Fetal rats were tolerized in utero with 10(5) Huh 7 cells. One day after birth, rats were transplanted with 5 x 10(6) Huh 7 cells and, a week later, inoculated with HCV, genotype 1.

RESULTS

In tolerized, transplanted, and HCV-infected rats, Huh 7 cells were found in the liver, and HCV viral replication was detected by the presence of negative strand HCV RNA. HCV levels in serum were measured at 11,000 copies/mL at week 4, peaked at 22,500 copies/mL by week 12. In tolerized, transplanted, inoculated rats, but not controls, serum alanine aminotransferase (ALT) values increased to 60 IU/L by week 4 and reached a peak of approximately 120 IU/L by week 13. Histology showed foci of mononuclear infiltrates in portal and central regions.

CONCLUSIONS

HCV-inoculated immunocompetent rats tolerized and transplanted with Huh 7 cells support HCV gene expression, viral replication, and develop biochemical and histologic evidence of hepatitis.

RNA interference: Antiviral weapon and beyond

RNA interference (RNAi) is a remarkable type of gene regulation based on sequence-specific targeting and degradation of RNA. The term encompasses related pathways found in a broad range of eukaryotic organisms, including fungi, plants, and animals. RNA interference is part of a sophisticated network of interconnected pathways for cellular defense, RNA surveillance, and development and it may become a powerful tool to manipulate gene expression experimentally. RNAi technology is currently being evaluated not only as an extremely powerful instrument for functional genomic analyses, but also as a potentially useful method to develop specific dsRNA based gene-silencing therapeutics. Several laboratories have been interested in using RNAi to control viral infection and many reports in Nature and in Cell show that short interfering (si) RNAs can inhibit infection by HIV-1, polio and hepatitis C viruses in a sequence-specific manner. RNA-based strategies for gene inhibition in mammalian cells have recently been described, which offer the promise of antiviral therapy.

Inhibitory mechanism on proliferation of hepatocellular carcinoma cell line by tetrandrine

AIM

To study the mechanism of tetrandrine (TTD) on proliferation and apoptosis of hepatic cell carcinoma (HCC) cell line.

METHODS

MTT colorimetry was used to evaluate the influence of TTD on proliferation of cells. Flow cytometry was used to test reactive oxygen species (ROS) levels in cells. Electrophoresis in 1.5% agarose gels was used to assess the DNA laddering.

RESULTS

Proliferation rate of HCC cell line stimulated by 10 and 20 μmol/L TTD at 24 h, 48 h, and 72 h was 90.1±1.0%, 77.5±2.0%, 70.2±2.9% and 56.6±1.6%, 61.6±2.0% and 47.2±1.9%, respectively (F = 40.025, P<0.001). O₂^- and H₂O₂. generated by HCC cell lines incubated with 0, 10 and 20 μmol/L TTD for 2 hours were 35 and 24.5%, 36.6 and 40.5%, 63.2 and 84.6%, respectively. Typical DNA ladder was observed after the cell line was incubated in 20 μmol/L TTD for 48 hours.

CONCLUSION

TTD can induce the apoptosis of ROS of hepatic cell carcinoma cell line by generation of ROS in a dose dependent manner.

Mutations in nonstructural 5A gene of hepatitis C virus and its response to interferon alfa

AIM

To investigate the relationship between NS5A_2209-2248 sequences and response to interferon therapy, and whether there is an IFN sensitivity determining region(ISDR) in the region of NS5A_2209-2248.

METHODS

We analyzed 11 patients with chronic HCV 1b infection who had received interferon alfa therapy for six months. Pretreatment serum samples were analyzed. The amino acid sequence of NS5A_2209-2248 was determined by direct sequencing of the HCV genome amplified by the polymerase chain reaction.

RESULTS

Among the 11 patients, only 1 was intermediate type, all the others were wild type. 2 of wild type patients showed complete response. Others were nonresponders. There was no significant difference in nucleotide and amino acid sequences between the two groups.The nucleotide and amino acid sequences changed after IFN treatment in one nonresponder.

CONCLUSION

The NS5A_2209-2248 region was highly conservative. In Chinease patients with chronic HCV 1b infection, there was no correlation between response to interferon and mutations in the NS5A gene. HCV quasispecies changed after IFN therapy.

Laminin induces the expression of cytokeratin 19 in hepatocellular carcinoma cells growing in culture

AIM: To study the abnormal cytokeratin (CK) expression, emergence of CK19 with or without CK7, in liver parenchymal cells and the role of laminin (LN), a basement membrane protein, in this process.

METHODS: Six hepatocellular carcinoma (HCC) cell lines were examined for different CKs, LN and its receptor by immunocytochemistry and Western blotting. Double immunofluorescent reaction, laser-scanning confocal microscopy and an in vitro induction procedure were used to demonstrate the role of LN in regulating CK19 expression in these cells.

RESULTS: Immunoreactivities for CK8, CK18, CK7 and the receptor for LN were observed in all the six HCC cell lines examined. However, CK19 was merely found in four of the six cell lines, and was in any case associated with LN expression. Laser-scanning confocal microscopy demonstrated the concomitant presence of these two molecules in most of the positive cells. In the two HCC cell lines, originally negative for CK19, addition of LN to the culture medium resulted in an induction of CK19 in a dose-dependent manner. Both the artificially induced and the intrinsic production of CK19 were completely blocked by an antibody to LN.

CONCLUSION: LN can induce expression of CK19 in HCC cells in vitro, providing direct evidence for our hypothesis that the abnormal hepatocytic CK19 expression in situ is due to pathologic LN deposition.

An in vitro system combined with an in-house quantitation assay for screening hepatitis C virus inhibitors

Hepatitis C virus (HCV) infection is a serious global health problem. Interferon-alpha (IFN-alpha) and ribavirin have demonstrated efficacy in the treatment of HCV infection; however, these therapies display many side effects. To screen the anti-HCV compounds from plants, we established an in vitro model for inoculation of HCV by centrifugation-facilitated method. The HCV RNA molecules were then quantitated by nested competitive reverse transcription-polymerase chain reaction (cRT-PCR) using fluorescein-labeled primers, and analyzed by ABI Prism 310. The positive and negative strands of HCV RNA were detectable in Vero cells on Day 7 post-infection, suggesting that the HCV RNA was present in the cell model system. The cell culture system was further used to screen the anti-HCV activities of 4 Chinese herbal formulas and 15 formula components. IFN-alpha showed an antiviral effect. The formulas exhibited no anti-HCV activities, while Arnebia euchroma, Thlaspi arvense, and Poncirus trifoliata displayed anti-HCV activities. Therefore, these results pointed out the possibility by using the cell culture system established in this study to screen the herb extracts for their anti-HCV activities.

Effect of alpha 2b interferon on inducement of mIL-2R and treatment of HCV in PBMC from patients with chronic viral hepatitis C

AIM: To study the level of membrane interleukin-2 receptor (mIL-2R) on surface of peripheral blood mononuclear cells (PBMC) and the therapeutic efficacy of alpha 2b interferon on the treatment of HCV-RNA in PBMC of patients with chronic hepatitis C and to compare the negative rates of HCV-RNA in PBMC, HCV-RNA and anti-HCV in serum.

METHODS: Before and after treatment of alpha 2b interferon, the level of mIL-2R of patients with chronic hepatitis C was detected by biotin-streptavidin (BSA). The therapeutic group (26 cases) was treated with alpha 2b interferon (3 MU/d) and control therapeutic group (22 cases) was treated with routine drugs (VitC, aspartic acid). The total course of treatment with alpha 2b interferon and routine drug was six months and per course of the treatment was three months. The levels of HCV-RNA in PBMC, HCV-RNA and anti-HCV in serum were detected before and after a course of the treatment.

RESULTS: Before and after treatment of alpha 2b interferon and routine drugs, the levels of mIL-2R in silence stage were (3.44 ± 0.77)% and (2.95 ± 0.72)%, the levels of mIL-2R in inducement stage were (33.62 ± 3.95)% and (30.04 ± 3.73)%. There was a significant difference between two groups (P < 0.01-P < 0.05). After treatment of alpha 2b interferon with 3 MU/d for two courses of the treatment, the total negative rates of HCV-RNA in the PBMC and HCV-RNA, anti-HCV in serum were 42.31% (11/26), 57.69% (15/26), 65.38%(17/26) respectively. After the treatment of routine drug, the negative rates of HCV-RNA in PBMC and HCV-RNA, anti-HCV in serum were 13.64% (3/22), 22.73% (5/22), 27.27% (6/22) respectively. There was high significant difference in the group treated with alpha 2b interferon and the group treated with routine drugs (P < 0.01-P < 0.05).

CONCLUSION: The mIL-2R can be induced by alpha 2b interferon during the treatment. The alpha 2b interferon has a definite effect on the treatment of HCV-RNA in PBMC. The curative effect of alpha 2b interferon is better than that of the routine drugs.

Inhibitory effect of IRES specific inhibitor RNA on HCV IRES mediated protein translation

AIM: To explore the inhibitory effect of internal ribosome entry site (IRES) specific inhibitor RNA (IRNA) on HCV IRES mediated protein translation in vivo.

METHODS: Human hepatic carcinoma cell line (HHCC) was transfected with the eukaryotic vectors of IRNA or mIRNA (pcRz-IRNA or pcRz-mIRNA), and then selected with G418 for 4 weeks. HHCC expressing IRNA or mIRNA was cotransfected with pCMVNCRluc containing HCV IRES. HHCC stably expressing pcHCVcluc was transfected with pcRz-IRNA, and pcRz-mIRNA, respectively, the luciferase activity was examined at desired time post-transfection.

RESULTS: The pCMVNCRluc was efficiently suppressed in HHCC expressing IRNA rather than the cell line expressing mIRNA. The IRES specific IRNA inhibited expression of HCV IRES mediated luc gene by 20% to 80% in pcHCVcluc expressing cell after transfection; However, no inhibitory effect of the mutant IRNA was observed.

CONCLUSION: pcHCVcluc could be expressed successfully in HHCC, and IRNA inhibited HCV IRES mediated gene expression in vivo.

Establishment of B-cell lymphoma cell lines persistently infected with hepatitis C virus in vivo and in vitro: the apoptotic effects of virus infection

Hepatitis C virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Studies of HCV replication and pathogenesis have so far been hampered by the lack of an efficient tissue culture system for propagating HCV in vitro. Although HCV is primarily a hepatotropic virus, an increasing body of evidence suggests that HCV also replicates in extrahepatic tissues in natural infection. In this study, we established a B-cell line (SB) from an HCV-infected non-Hodgkin's B-cell lymphoma. HCV RNA and proteins were detectable by RNase protection assay and immunoblotting. The cell line continuously produces infectious HCV virions in culture. The virus particles produced from the culture had a buoyant density of 1.13 to 1.15 g/ml in sucrose and could infect primary human hepatocytes, peripheral blood mononuclear cells (PBMCs), and an established B-cell line (Raji cells) in vitro. The virus from SB cells belongs to genotype 2b. Single-stranded conformational polymorphism and sequence analysis of the viral RNA quasispecies indicated that the virus present in SB cells most likely originated from the patient's spleen and had an HCV RNA quasispecies pattern distinct from that in the serum. The virus production from the infected primary hepatocytes showed cyclic variations. In addition, we have succeeded in establishing several Epstein-Barr virus-immortalized B-cell lines from PBMCs of HCV-positive patients. Two of these cell lines are positive for HCV RNA as detected by reverse transcriptase PCR and for the nonstructural protein NS3 by immunofluorescence staining. These observations unequivocally establish that HCV infects B cells in vivo and in vitro. HCV-infected cell lines show significantly enhanced apoptosis. These B-cell lines provide a reproducible cell culture system for studying the complete replication cycle and biology of HCV infections.

Preparation of human single chain Fv antibody against hepatitis C virus E2 protein and its identification in immunohistochemistry

AIM: To screen human single chain Fv antibody (scFv) against hepatitis C virus E2 antigen and identify its application in immunohistochemistry.

METHODS: The phage antibody library was panned by HCV E2 antigen, which was coated in microtiter plate. After five rounds of biopanning, 56 phage clones were identified specific to HCV E2 antigen. The selected scFv clones were digested by Sfi I/Not I and DNA was sequenced. Then it was subcloned into the vector pCANTAB5E for expression as E-tagged soluble scFv. The liver tissue sections from normal person and patients with chronic hepatitis B and chronic hepatitis C were immunostained with HCV E2 scFv antibody.

RESULTS: The data of scFv-E2 DNA digestion and DNA sequencing showed that the scFv gene is composed of 750 bp. ELISA and immunohistochemistry demonstrated that the human single chain Fv antibody against hepatitis C E2 antigen has a specific binding character with hepatitis virus E2 antigen and paraffin-embedded tissue, but did not react with liver tissues from healthy persons or patients with chronic hepatitis B.

CONCLUSION: We have successfully screened and identified HCV E2 scFv and the scFv could be used in the immunostaining of liver tissue sections from patients with chronic hepatitis C.

Full-length core sequence dependent complex-type glycosylation of hepatitis C virus E2 glycoprotein

AIM: To study HCV polyprotein processing is important for the understanding of the natural history of HCV and the design of vaccines against HCV. The purpose of this study is to investigate the affection of context sequences on hepatitis C virus (HCV) E2 processing.

METHODS: HCV genes of different lengths were expressed and compared in vaccinia virus/T7 system with homologous patient serum S94 and mouse anti-serum M_E2116 raised against E. coli-derived E2 peptide, respectively. Deglycosylation analysis and GNA (Galanthus nivalus) lectin binding assay were performed to study the post-translational processing of the expressed products.

RESULTS: E2 glycoproteins with different molecular weights (~75 kDa and ~60 kDa) were detected using S94 and M_E2116, respectively. Deglycosylation analysis showed that this difference was mainly due to different glycosylation. Endo H resistance and its failure to bind to GNA lectin demonstrated that the higher molecular weight form (75 kDa) of E2 was complex-type glycosylated, which was readily recognized by homologous patient serum S94. Expression of complex-type glycosylated E2 could not be detected in all of the core-truncated constructs tested, but readily detected in constructs encoding full-length core sequences.

CONCLUSION: The upstream conserved full-length core coding sequence was required for the production of E2 glycoproteins carrying complex-type N-glycans which reacted strongly with homologous patient serum and therefore possibly represented more mature forms of E2. As complex-type N-glycans indicated modification by Golgi enzymes, the results suggest that the presence of full-length core might be critical for E1/E2 complex to leave ER. Our data may contribute to a better understanding of the processing of HCV structural proteins as well as HCV morphogenesis.

Discharge planning for the mentally disabled. Genet Vaccines Ther. 1986;12:55-67. [PMID: 21466709 DOI: 10.1186/1479-0556-9-7] [Cited by in Crossref: 15] Hepatitis C virus (HCV) is a major cause of chronic liver diseases including steatosis, cirrhosis and hepatocellular carcinoma. Currently, there is no vaccine available for prevention of HCV infection due to high degree of strain variation. The current treatment of care, Pegylated interferon α in combination with ribavirin is costly, has significant side effects and fails to cure about half of all infections. The development of in-vitro models such as HCV infection system, HCV sub-genomic replicon, HCV producing pseudoparticles (HCVpp) and infectious HCV virion provide an important tool to develop new antiviral drugs of different targets against HCV. These models also play an important role to study virus lifecycle such as virus entry, endocytosis, replication, release and HCV induced pathogenesis. This review summarizes the most important in-vitro models currently used to study future HCV research as well as drug design

Hepatitis C virus (HCV) is a major cause of chronic liver diseases including steatosis, cirrhosis and hepatocellular carcinoma. Currently, there is no vaccine available for prevention of HCV infection due to high degree of strain variation. The current treatment of care, Pegylated interferon α in combination with ribavirin is costly, has significant side effects and fails to cure about half of all infections. The development of in-vitro models such as HCV infection system, HCV sub-genomic replicon, HCV producing pseudoparticles (HCVpp) and infectious HCV virion provide an important tool to develop new antiviral drugs of different targets against HCV. These models also play an important role to study virus lifecycle such as virus entry, endocytosis, replication, release and HCV induced pathogenesis. This review summarizes the most important in-vitro models currently used to study future HCV research as well as drug design.