Construction of recombinant fusion protein of influenza, a virus neuraminidase and heat shock protein 70 gene: expression in baculovirus and bioactivity

Background: Two structural antigens, hemagglutinin and neuraminidase, are a major component for the development of influenza vaccine candidates. Recombinant vaccines are produced by a simple method, although expected to induce an immune response to a specific antigen, remaining to be further improved for their high effectiveness. In general, heat shock protein 70 of Mycobacterium tuberculosis, as a potent adjuvant, is commonly used to improve antigen-presenting cell (APC) function and thereby elicit T lymphocytes. Objective: The purpose of this research was to evaluate the efficacy of the NA antigen fused to the C-terminus of HSP70, as a vaccine candidate, in the induction of potent, protective immune answers specific to the vaccine antigen. Material and Method: The NA gene was strengthened via a polymerase chain reaction and then cloned to a eukaryotic expressing vector pFastBac HTA. Subsequently, a recombinant NA protein fusing to HSP70 was expressed in Baculovirus. The purity of the expressed NA-HSP70 fusion protein was investigated on the SDS-PAGE electrophoresis. Western blot was carried out to investigate the expression of NA-HSP70. Additionally, an immunofluorescence assay was used qualitatively to assess the biological and antigenicity activity profiles of the protein of recombinant, NA-HSP70, on the infected Sf9 cell surface by using immunized rabbit antiserum. Result and conclusion: Interestingly, the findings in the present studies suggested that HSP proteins have the ability to both stimulate and increase potent humoral- and cell-mediated immune responses, and play an adjuvant role when combined with other proteins. Therefore, a recombinant protein fusing to HSP raised hope regarding the development of an HSP-based vaccine.