Adjuvant Effect of Immunomodulators of Plant Origin on the Immune Responses Induced by HCV Envelope Proteins

Abstract

In the present study, the major objective was to assess the immunomodulatory effect of natural plant extracts; Echinacea purpurea and Nigella sativa when used as immunoadjuvants on the immunogenicity of HCV-envelope protein. For that purpose, the region encoding the E1-E2 domain was amplified from RNA isolated from HCV-4a infected patients' sera by RT-PCR and first confirmed by internal PCR that resulted in two fragment of molecular weights of 795 and 731 bp as expected molecular weight predicted from the published sequence of HCV-Ed43 (Y11604), and then further confirmed by nucleotide and protein blast analysis that revealed that our herein characterized HCV-E sequence is a novel one. Bacterial expression protocol of HCV-E was optimized to overcome the reported protein toxicity associated with extreme hydrophobicity of this region of the HCV genome. The most suitable culture media was found to be 2XYT media using IPTG inducer final concentration of 0.05mM, and post induction temperature 25oC for 18 h. Such conditions were optimized to scale up the selected culture media to obtain the maximum yield of purified protein as 88μg/L; a suitable yield