Expression of NS3/NS4A Proteins of Hepatitis C Virus in Huh7 Cells Following Engineering Its Eukaryotic Expression Vector

Background: Although the development of novel therapeutic regimens to combat hepatitis C virus (HCV) infection have been speeded up with successful results, no efficient vaccines exist yet. Objectives: This study aimed to construct a eukaryotic expression vector encoding nonstructural proteins, NS3/NS4A, of HCV genotype 3a, and evaluate its expression on Huh7 cell surface. Materials and Methods: The NS3/NS4A sequence was isolated from a patient with HCV-3a chronic infection, cloned into intermediate vector pTZ57R/T, and then used for engineering a mammalian expression vector, pDisplay, to direct the respective protein to the secretory pathway and anchor it to the plasma membrane. The expression of the protein in Huh7 cell, which was transiently transfected with the vector using Lipofectamine, was determined by immunocytochemical staining assay with fluorescein isothiocyanate (FITC)-conjugated antibodies to the HA/myc tags located besides the fusion fragment. Results: The results showed that the fragment was successfully amplified and cloned into a eukaryotic expression vector. Sequencing and enzyme digestion analysis confirmed the cloned gene completion and its correct position in the pDisply-NS3/NS4A plasmid. Immunocytochemical staining revealed that the target protein was expressed as a membrane-anchored protein in the Huh7 cells. Conclusions: This study can serve as a fundamental experiment for the construction of a NS3/NS4A eukaryotic expression vector and its expression in mammalian cells. Further research is underway to evaluate the fragment immunogenicity in lab animal models.