Study the capacity of recombinant HCV core+1 protein to induce immune responses in combination with different adjuvants

Hepatitis C virus (HCV) genome contains a large open reading frame coding for a polyprotein that is cleaved into ten proteins. Recently, a new protein, named core+1, has been described to be expressed through a ribosomal frame shift within the capsid-encoding sequence. To address these possibilities, core+1 was produced in E.coli and the purified protein was evaluated for the immunological properties. The core+1corresponding nucleotide sequence was created by PCR-based induction of a +1 frame shift mutation within the core gene template. The amplicon was cloned into the pET-24a vector and expressed in E.coli host. The expressed protein was purified under denaturing condition and after refolding steps was characterized by SDS-PAGE and Western Blotting. The immunization potential of core+1 with various adjuvant (Freunds (C/IFA), Montanide ISA 206 and IMS 1312, pluronic acid (F127) and imiquimod (IMIQ) was assessed in Balb/c mice. ELISA-based assays were used to analyze the humoral immune responses. The yield of E.coli-derived core+1 was 5 mg/ L of culture media and antigenicity of this protein was confirmed by western blotting. All the core+1/adjuvant formulations significantly developed the anti- core+1 IgG responses in the immunized mice but C/IFA and ISA206 elicited the highest antibody titers. ISA 206 and IMS 1312 formulation of core+1 induced strong Th1/Th2 responses. Our results indicated that core+1 formulation with various adjuvants may elicit the different immune response profiles (Th1/Th2). Thus core+1 might be a potential component of future HCV vaccine too.