Construction and characterization of a novel superantigen fusion protein: bFGF/SEB

As one of the bacterial superantigens, Staphylococcal enterotoxins (SEs) are potent activators of T cells, especially for those expressing T cell receptor V(beta) chains, and can induce the production of cytokines such as IFN-gamma, TNF-alpha, IL-1, IL-2, IL-6, IL-12, etc. Thus, SEs could be used in tumor-targeting therapy when cooperated with the vectors that can specifically recognize the tumor cells.

The coding sequences of Staphylococcal enterotxin B (SEB) was amplified and fused with human basic fibroblast growth factor (bFGF). Recombinant protein SEB and fusion protein bFGF/SEB were expressed and purified. The biological activity was detected, including splenocytes proliferation, cytokine production, and cytotoxicity in tumor cells in vitro. In addition, the binding of bFGF/SEB with tumor cells and the tumor cell apoptosis were also tested by immunofluorescent technique.

The fusion protein bFGF/SEB had similar biological activities compared with natural SEA and recombinant SEB, including tumor-inhibition ratio.

The recombinant bFGF/SEB-fusion protein was shown to retain the superantigenic activity of SEB, and might be a novel promising immunotherapeutic agent for the treatment of some carcinomas.