Viral Load Analysis of Hepatitis C Virus in Huh7.5 Cell Culture System

The hepatitis E virus ORF1 hypervariable region confers partial cyclophilin dependency

Hepatitis E virus (HEV) is an emerging pathogen responsible for more than 20 million cases of acute hepatitis globally per annum. Healthy individuals typically have a self-limiting infection, but mortality rates in some populations such as pregnant women can reach 30 %. A detailed understanding of the virus lifecycle is lacking, mainly due to limitations in experimental systems. In this regard, the cyclophilins are an important family of proteins that have peptidyl-prolyl isomerase activity and play roles in the replication of a number of positive-sense RNA viruses, including hepatotropic viruses such as hepatitis C virus (HCV). Cyclophilins A and B (CypA/B) are the two most abundant Cyps in hepatocytes and are therefore potential targets for pan-viral therapeutics. Here, we investigated the importance of CypA and CypB for HEV genome replication using sub-genomic replicons. Using a combination of pharmacological inhibition by cyclosporine A (CsA), and silencing by small hairpin RNA we find that CypA and CypB are not essential for HEV replication. However, we find that silencing of CypB reduces replication of some HEV isolates in some cells. Furthermore, sensitivity to Cyp silencing appears to be partly conferred by the sequence within the hypervariable region of the viral polyprotein. These data suggest HEV is atypical in its requirements for cyclophilin for viral genome replication and that this phenomenon could be genotype- and sequence-specific.

Downregulation of hepatitis C virus replication by miR-196a using lentiviral vectors

Hepatitis C virus (HCV) is a positive-sense, single-stranded RNA virus that causes chronic hepatitis and hepatocellular carcinoma. Cellular microRNAs (miRNAs) directly modulate the viral infectivity and indirectly through targeting virus-related host factors. They play an essential role in the progression of different stages of HCV infection. The roles of miR-196 family in HCV infection and hepatocellular carcinoma progression remain poorly understood. Using ViTa databases, miR-196a as a high-score miRNA targeting the NS₅ A region of HCV genome was selected. Using dual luciferase assay and an established cell-cultured HCV (HCVcc) system, the effect of miR-196a on HCV genome was assessed. In silico analysis demonstrated the significant role of miR-196a in the downregulation of HCV replication. Using dual luciferase assay, the liver-specific miR-196a and NS₅ A gene binding was confirmed. To assess the experimental role of miR-196a, an HCVcc system was established in the Huh 7.5 cell lines. The HCV-RNA 1b derived from an infected patient was transfected into Huh 7.5 cells containing miR-196a lentiviral vectors (Huh 7.5/miR-196a), mocks (Huh 7.5/mock vector), and naïve Huh 7.5 cells. The rate of reduction of the HCV genome replication was assessed using relative real-time PCR assay. These results represent miR-196a overexpression and its roles in regulating HCV genome replication. However, miR-196a may inhibit HCV replication and accelerate the early stages of apoptosis. Overexpression of miR-196a in Huh 7.5 replicon cell is a potential new strategy to prevent hepatitis C infection. The results of this study suggest that miR-196a directly downregulates HCV replication and may serve as a new antiviral therapy.

Secretory Expression of a Chimeric Peptide in Lactococcus lactis: Assessment of its Cytotoxic Activity and a Deep View on Its Interaction with Cell-Surface Glycosaminoglycans by Molecular Modeling

Nowadays, cancer remains a major cause of death affecting millions of people. Currently, the antimicrobial peptides (AMPs) as potent anticancer therapeutic agents offer specificity and low levels of side effects in cancer therapy. In the present study, a cationic chimeric peptide (cLFchimera), derived from camel lactoferrin, was expressed as a secretory peptide using P170 expression system in L. lactis. Peptide purification was carried out using Ni-NTA agarose column from culture medium with 21 μ/mL concentration. The recombinant peptide was investigated for its activity against four tumor and one normal cell line. The cLFchimera was more active against two tumor cell lines (chondrosarcoma and colorectal cancer cells), but the activity against two other tumor cell lines (hepatoma and breast cancer cell line) and normal cells was low. Finally, to have better insight into the mode of action of the peptide on cytotoxic activity, we examined the interaction of cationic peptide with two glycosaminoglycans (GAGs), heparan sulfate (HS) and chondroitin sulfate (CS), as the two most anionic molecules on the cell surface by molecular dynamic simulation. The results of in silico analysis showed that the cLFchimera interacted with HS and CS with a totally different amino acid profile. Hydrogen bonding screening in GAGs-peptide complexes revealed K²¹, V²³ and I³, R¹⁶ are the dominant amino acids involved in peptide-HS and CS interaction, respectively. Overall, the results of this investigation showed the P170 expression system successfully expressed a cationic peptide with potent anticancer activity. Moreover, molecular docking analysis revealed the pattern of peptide interaction with negatively charged membrane molecules.

Application of Impedance-Based Techniques in Hepatology Research

There are a variety of end-point assays and techniques available to monitor hepatic cell cultures and study toxicity within in vitro models. These commonly focus on one aspect of cell metabolism and are often destructive to cells. Impedance-based cellular assays (IBCAs) assess biological functions of cell populations in real-time by measuring electrical impedance, which is the resistance to alternating current caused by the dielectric properties of proliferating of cells. While the uses of IBCA have been widely reported for a number of tissues, specific uses in the study of hepatic cell cultures have not been reported to date. IBCA monitors cellular behaviour throughout experimentation non-invasively without labelling or damage to cell cultures. The data extrapolated from IBCA can be correlated to biological events happening within the cell and therefore may inform drug toxicity studies or other applications within hepatic research. Because tight junctions comprise the blood/biliary barrier in hepatocytes, there are major consequences when these junctions are disrupted, as many pathologies centre around the bile canaliculi and flow of bile out of the liver. The application of IBCA in hepatology provides a unique opportunity to assess cellular polarity and patency of tight junctions, vital to maintaining normal hepatic function. Here, we describe how IBCAs have been applied to measuring the effect of viral infection, drug toxicity /IC50, cholangiopathies, cancer metastasis and monitoring of the gut-liver axis. We also highlight key areas of research where IBCAs could be used in future applications within the field of hepatology.

Autophagy induction plays time-dependent role in viral load of HCV infected Huh7.5 cell line

Autophagy provides an initial membranous platform for incoming hepatitis C virus (HCV) RNA translation and immune evasion. Once HCV replication is established, this infrastructure will be unnecessary for translation of HCV RNA progeny. So, the autophagy plays key role in the replication and immune pathogenesis of HCV virus. The aim of this study was to study the effect of autophagy induction in Huh7.5 cell on virus titer. The Huh7.5 cell was transfected with recombinant pcDNA-Beclin1. The autophagy induction was evaluated via microtubule associated protein 1 light chain 3 staining as autophagy formation marker using flow cytometry. The HCV (JFH1) was inoculated 12-h post-transfection. Next, to evaluate the viral load, viral RNA was extracted after 24 and 48 h and virus titer was calculated using real-time PCR. The result of the current study shows that the induction of autophagy before virus infection was able to enhance virus yield from 4 × 10³ copies/mL to 1 × 10⁴ copies/mL at 24-h post-infection, but reduced viral load after 48 h up to 6 × 10³ copies/mL. The study of cross-talk between autophagy and HCV may bring new hope for human intervention and treatment of HCV. Also, it opens new avenue to improve virus cultivation in cell culture and understanding HCV and host cell responses. © 2018 IUBMB Life, 71(1):41-44, 2019.

Design, Construction and Evaluation of 1a/JFH1 HCV Chimera by Replacing the Intergenotypic Variable Region

BACKGROUND

The E2 glycoprotein is an important encoded hepatitis C virus (HCV) protein that contains three different variable regions.

OBJECTIVES

The aim of the present study was to construct an HCV 1a/JFH1 chimeric virus by replacing the intergenotypic variable region (igVR) fragment of the highly variable region of the E2 gene of the Japanese Fulminant hepatitis genotype 2a JFH1 virus with a similar region of HCV genotype 1a. This chimera was produced as a model virus with the ability to be cultured. We analyzed the adapted virus and the variations of nucleic acids within it.

METHODS

Specific primers were designed for the igVR of HCV genotype 1a followed by the overlap-PCR method for the synthesis of the desired DNA fragment. The amplified igVR-1a chimera gene and pFL-J6/JFH were digested by KpnI and BsiWI restriction enzymes, and the fragment was ligated into pFL-J6/JFH. The recombinant vector was transformed into Escherichia coli JM109 strain competent cells. All clones were confirmed by colony PCR using specific primers, and the confirmed recombinant vector was sequenced. The recombinant vector was targeted for RNA synthesis by T7 RNA polymerase enzyme. RNA transfection was performed in the Huh7.5 cell line. Virus production in several passages and the evaluated viral load were studied using quantitative real-time PCR and ELISA methods. After 30 passages, the RNA virus was extracted and cloned in PCDNA3.1 vector, and was then sequenced.

RESULTS

Quantitative real-time PCR results showed 11,292,514 copies/mL of chimeric virus production in cell culture. The virus production was confirmed using ELISA, which showed a virus core production of 808.2 pg/mL. The results of cloning and sequencing showed that some of the nucleic acids in the chimera virus were changed, affecting the viral behavior in the cell culture.

CONCLUSIONS

Real-time PCR and ELISA showed high levels of production of 1a/JFH1 chimeric HCV in the Huh7.5 cell culture. The constructed virus can be used for future studies, including the development of new HCV drugs and vaccines.

Evaluation of the eukaryotic expression of mtb32C-hbha fusion gene of Mycobacterium tuberculosis in Hepatocarcinoma cell line

BACKGROUND AND OBJECTIVES

HBHA and Mtb32C have been isolated from culture supernatants of Mycobacterium tuberculosis (M. tuberculosis) and Mycobacterium bovis (M. bovis) and their immunogenicity previously studies have been confirmed. In this study, capability of constructed vector containing two mycobacterial immunodaminant antigens (Mtb32C-HBHA), in producing new chimeric protein under the in-vitro condition was examined.

MATERIALS AND METHODS

In present study Huh7.5 cells was transfected with Mtb32C-HBHA -pCDNA3.1+ recombinant vector using the calcium phosphate method and expression of chimeric protein was assessed by RT-PCR and Western blot methods.

RESULTS

Results of RT-PCR and Western blot showed expression of 35.5 KD recombinant protein (Mtb32C-HBHA) in this cell line.

CONCLUSION

The constructed vector can produce two highly immunogenic antigens that fusion of them to gather makes chimeric antigen with new traits. Other attempts are needed to evaluate specific properties of this new antigen such as molecular conformation modeling and immunologic characteristics in future studies.