Prokaryotic Expression of Influenza A virus Nucleoprotein Fused to Mycobacterial Heat Shock Protein70

Background and Aims: The novel approaches in influenza vaccination have targeted more conserved viral proteins such as nucleoprotein (NP) to provide cross protection against all serotypes of influenza A viruses. Influenza specific cytotoxic T lymphocytes (CTL) are able to lyse influenza-infected cells by recognition of NP, the major target molecule in virus for CTL responses. On the other hand, studies suggest that fusing of molecular adjuvants such as Heat Shock Protein 70 (HSP70), member of intracellular chaperon super families, with an antigen can induce the cellular and humoral specific responses better than the same induced by antigen alone. It is shown that the C-Terminal of HSP70 (ctHSP70) is the main domain responsible for inducing immunity system. Materials and Methods: In this study the open reading frame of NP gene from Influenza A virus (PR/8/34) and C-Terminal (359-625) domain of HSP70 gene from Mycobacterium tuberculosis were amplified and cloned into expression pET28a vector independently. Then the N-terminal of whole NP protein was fused to truncated HSP70 in same vector. The fidelity of cloned genes was confirmed by sequencing. All three types of clones were expressed in E. coli BL21 and confirmed by SDS-PAGE and Western blot analysis. Results: Results showed the integrity of vector constructs and well expression of NP, ctHSP70 and fusion form of ctHSP70-NP recombinant proteins in BL21 host cells. Conclusion: ctHSP70-NP fusion protein produced could be considered and evaluated as a universal influenza vaccine which its immunogenicity potential needs to be assessed in animal models along with proper control groups including recombinant NP and ctHSP70 proteins.