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

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. 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. 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. 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.