| Research Abstract |
Toxin-production is a main virulence factor in Bacillus anthracis, which consists of protective antigen (PA), lethal factor (LF) and edema factor (EF). Only LE and EF are not toxic by themselves, but become active with binding to PA. Firstly, PA non-specifically binds onto the mammalian host cell surfaces, then PA of 83 Kdal is degradated into two parts of PA63 (63 Kdal) and PA20 (20 Kdal) by some kinds of host-originating proteases as furin. Finally, PA20 releases from the cell surface and PA63 binds onto the cell surface yet. EF and LF can bind on such degradated PA63 only, then can invade into the host cell to exhibit both toxic actions. In the case of LF, its N-terminal 255 amino acid residues (LF255) is essential for the binding, that is the binding domain, and other part of the LF is the toxin domain. Therefore, if we can construct a fusion protein of the LF255 and some protein, it is easy to inject the protein with PA63. This system is used for a vaccine delivery system using T-cell epitope. In this study, we tried to make LF255 and FliC, which is a main flagella protein of Salmonella and have some T-cell epitopes in the molecule. First we constructed a vector system to make a fusion protein using LF255, and then we expressed a LF255-Flic fusion protein. We obtained a significant protection against Salmonella infection in mice
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