Cloning, expression and purification of hemagglutinin conserved domain (HA2) of influenza A virus, to be used in broad-spectrum subunit vaccine cocktails

Introduction: Influenza virus has several conserved peptides which have the capacity to be used as suitable candidates for appropriate and stable vaccine production against different types of influenza viruses. One of these peptides is HA2, the hemagglutinin stalk domain which mediates the membrane fusion and is conserved amongst different sub-types of influenza virus. This peptide is a good candidate for participation in vaccine structure to induce immunity and antibody production. The ensued antibody may hamper the membrane fusion and subsequently the virus propagation. Methods: The peptide sequence of HA2 from influenza virus A/Tehran/18/2010 (H1N1) was analyzed using in silico tools in order to evaluate its physicochemical properties and identification of its best immunogenic sites. The confirmed sequence was amplified and cloned into a pET28a vector and the recombinant protein was over-expressed prokaryotically and confirmed by Western blotting. Results: The bioinformatics data showed that HA2 peptide stability and immunogenicity. The generated HA2 construct was confirmed by PCR, endonuclease restriction enzyme analysis and sequencing. The expression of HA2 was confirmed by SDS-PAGE and Western blot analysis. The results on the cell lysate demonstrated the high expression of HA2 subunit of the influenza virus hemagglutinin. Conclusion: One of the disadvantages of the current flu vaccines is that they cannot produce efficient broad-spectrum cellular and humoral immune responses against all subtypes of the virus due to the genetic variation of the virus. Therefore, such a conserved protein is potentially a good candidate for production of a broad-spectrum vaccine to prevent influenza epidemics and pandemics.