Optimization of transfection methods for Huh­7 and Vero cells: a comparative study

Availability of an efficient transfection protocol is the first determinant in success of gene transferring studies in mammalian cells which is accomplished experimentally for every single cell type. Herein, we provide data of a comparative study on optimization of transfection condition by electroporation and chemical methods for Huh-7 and Vero cells. Different cell confluencies, DNA/reagent ratios and total transfection volumes were optimized for two chemical reagents including jetPEI™ and Lipofectamine™ 2000. Besides, the effects of electric field strength and pulse length were investigated to improve electroporation efficiency. Transfection of cells by pEGFP-N1 vector and tracking the expression of GFP by FACS and Fluorescence Microscopy analysis were the employed methods to evaluate transfection efficiencies. Optimized electroporation protocols yielded 63.73 ± ± 2.36 and 73.9 ± 1.6 % of transfection in Huh-7 and Vero cells respectively, while maximum achieved level of transfection by jetPEI™ was respectively 14.2 ± 0.69 and 28 ± 1.11 % for the same cells. Post transfectional chilling of the cells did not improve electrotransfection efficiency of Huh-7 cells. Compared to chemical based reagents, electroporation showed the superior levels of transfection in both cell lines. The presented protocols should satisfy most of the experimental applications requiring high transfection efficiencies of these two cell lines.Наличие эффективного протокола трансфекции является первым условием успешных исследований по переносу генов в клетки млекопитающих, что достигается экспериментально для каждого конкретного типа клеток. Здесь мы приводим данные сравнительного исследования по оптимизации условий трансфекции клеток Huh-7 и Vero с помощью электропорации и химическими методами. Для двух химических соединений, jetPEI™ и Lipofectamine™ 2000, были оптимизированы сочетания различных клеток, соотношения ДНК/реагент и общие объемы трансфекции. Кроме того, для улучшения эффективности электропорации было изучено влияние силы электрического поля и длины импульса. Трансфекция клеток с помощью вектора pEGFP-N1, определение экспрессии GFP с помощью FACS и флюоресцентная микроскопия были использованы для оценки эффективности трансфекции. В оптимизированных протоколах достигалась трансфекция на уровне 63.73 ± 2.36 и 73.9 ± 1.6 % в клетках Huh-7 и Vero соответственно, в то время как максимальный уровень трансфекции с помощью jetPEI™ составлял 14.2 ± 0.69 и 28 ± 1.11 % для тех же клеток. Охлаждение клеток после трансфекции не улучшало эффективность электротрансфекции клеток Huh-7. В обеих клеточных линиях электропорация позволила достичь более высокого уровня трансфекции по сравнению с использованием химических реагентов. Представленный протокол может быть пригодным для большинства экспериментальных манипуляций, которые требуют высокого уровня трансфекции исследуемых клеточных линий

Bidirectional lipid droplet velocities are controlled by differential binding strengths of HCV Core DII protein

Host cell lipid droplets (LD) are essential in the hepatitis C virus (HCV) life cycle and are targeted by the viral capsid core protein. Core-coated LDs accumulate in the perinuclear region and facilitate viral particle assembly, but it is unclear how mobility of these LDs is directed by core. Herein we used two-photon fluorescence, differential interference contrast imaging, and coherent anti-Stokes Raman scattering microscopies, to reveal novel core-mediated changes to LD dynamics. Expression of core protein’s lipid binding domain II (DII-core) induced slower LD speeds, but did not affect directionality of movement on microtubules. Modulating the LD binding strength of DII-core further impacted LD mobility, revealing the temporal effects of LD-bound DII-core. These results for DII-core coated LDs support a model for core-mediated LD localization that involves core slowing down the rate of movement of LDs until localization at the perinuclear region is accomplished where LD movement ceases. The guided localization of LDs by HCV core protein not only is essential to the viral life cycle but also poses an interesting target for the development of antiviral strategies against HCV

The Kinase Inhibitor SFV785 Dislocates Dengue Virus Envelope Protein from the Replication Complex and Blocks Virus Assembly

Dengue virus (DENV) is the etiologic agent for dengue fever, for which there is no approved vaccine or specific anti-viral drug. As a remedy for this, we explored the use of compounds that interfere with the action of required host factors and describe here the characterization of a kinase inhibitor (SFV785), which has selective effects on NTRK1 and MAPKAPK5 kinase activity, and anti-viral activity on Hepatitis C, DENV and yellow fever viruses. SFV785 inhibited DENV propagation without inhibiting DENV RNA synthesis or translation. The compound did not cause any changes in the cellular distribution of non-structural 3, a protein critical for DENV RNA synthesis, but altered the distribution of the structural envelope protein from a reticulate network to enlarged discrete vesicles, which altered the co-localization with the DENV replication complex. Ultrastructural electron microscopy analyses of DENV-infected SFV785-treated cells showed the presence of viral particles that were distinctly different from viable enveloped virions within enlarged ER cisternae. These viral particles were devoid of the dense nucleocapsid. The secretion of the viral particles was not inhibited by SFV785, however a reduction in the amount of secreted infectious virions, DENV RNA and capsid were observed. Collectively, these observations suggest that SFV785 inhibited the recruitment and assembly of the nucleocapsid in specific ER compartments during the DENV assembly process and hence the production of infectious DENV. SFV785 and derivative compounds could be useful biochemical probes to explore the DENV lifecycle and could also represent a new class of anti-virals

An Integrated Transcriptomic and Meta-Analysis of Hepatoma Cells Reveals Factors That Influence Susceptibility to HCV Infection

Hepatitis C virus (HCV) is a global problem. To better understand HCV infection researchers employ in vitro HCV cell-culture (HCVcc) systems that use Huh-7 derived hepatoma cells that are particularly permissive to HCV infection. A variety of hyper-permissive cells have been subcloned for this purpose. In addition, subclones of Huh-7 which have evolved resistance to HCV are available. However, the mechanisms of susceptibility or resistance to infection among these cells have not been fully determined. In order to elucidate mechanisms by which hepatoma cells are susceptible or resistant to HCV infection we performed genome-wide expression analyses of six Huh-7 derived cell cultures that have different levels of permissiveness to infection. A great number of genes, representing a wide spectrum of functions are differentially expressed between cells. To focus our investigation, we identify host proteins from HCV replicase complexes, perform gene expression analysis of three HCV infected cells and conduct a detailed analysis of differentially expressed host factors by integrating a variety of data sources. Our results demonstrate that changes relating to susceptibility to HCV infection in hepatoma cells are linked to the innate immune response, secreted signal peptides and host factors that have a role in virus entry and replication. This work identifies both known and novel host factors that may influence HCV infection. Our findings build upon current knowledge of the complex interplay between HCV and the host cell, which could aid development of new antiviral strategies

Designing & producing polytope DNA vaccine containing HBsAg gene for the induction of protective immunity against hepatitis C

Background: Considering the immunosuppressive effects and prevalent mutations in some HCV antigens, induction of CD8+ T cell responses is focused on conserved and critical epitopes which as a multi-epitope vaccine can prevent the chronic nature of the disease. Materials and Methods: Two immunodominant HLA-A2-restricted human epitopes (E2614-622 and NS31406-1415) and two H-2d-restricted mouse epitopes (core132-142 and E2405-414) were designed in a sequential tandem, predicted by immunoinformatic analyses. Following the synthesis, related nucleotide sequence was cloned into the pcDNA3.1 vector with and without the fusion of hepatitis B surface antigen (HBsAg). Two constructed plasmids (pcDNA3.1.HPOL and pcDNA3.1.POL, respectively) were evaluated for the protein expression and secretion in Cos-7 cell line. After the vaccination of BALB/c mice (n=6 in each group) with different DNA and peptide immunization regimens, CD8+ T cell activity as well as the type and protective potency of the induced responses were evaluated. Results: Despite the induction of epitope-specific responses in pcDNA3.1.POL injected mice, the group immunized with pcDNA3.1.HPOL indicated a significant increase in the number and activity of CD8+ T cells (P<0.05). Peptide boosting of this group (formulated in two human-compatible adjuvant) still led to the more activation of CD8+ cells, induction of Th1 response and the inhibition of tumor model growth (P<0.05). Conclusion: Fusion of HBsAg as a particle-forming sequence and the source of helper epitopes along the DNA-prime/peptide-boosting immunization regimen are proposed as two promising strategies to improve the CTL multi-epitope vaccines against HCV

Evaluation of a Native Preparation of HCV Core Protein (2-122) For Potential Applications in Immunization, Diagnosis and Mab Production

Infection with hepatitis C virus (HCV) is a worldwide problem. Among HCV proteins, core antigen (Ag), besides its importance for diagnostic application is a prime candidate for component of a vaccine. Herein, we report results of studies on production of the hydrophilic domain of core Ag (2-122) in native conformation by an arabinose induction system in E.coli and the primary characterization of this recombinant protein for applications in diagnosis, immunization and mAb production. Recombinant core (r-Core) was able to detect anti-core antibodies in HCV positive serum samples in a dilution rate of 1/3200. It was also capable to elicit a potent anti-HCV humoral immune response in BALB/c mice. Finally, we established two stable clones of hybridoma which shown to produce specific and sensitive mAbs against the core protein. HCV core was able to elicit a broad range of antibody specificities depending on the immunogen conformation. Therefore, it may be possible to get new mAbs with higher affinities towards native conformation of core Ag