Evaluating and Comparing Immunization Level of the Recombinant Proteins, Binding Domain of Tetanus Neurotoxin and B Subnnit of Heat Labile Toxin of Escherichia coli, and their Relation to Immunological Memory

Heat labile toxin (LT) is one of the virulence factors of Enterotoxigenic Escherichia coli. B subunit of LT (LHB) is the binding subunit and can induce six months immunity in humans. Tetanus toxin of Clostridium Tetani causes the fatal disease، tetanus. This toxoid induces two years immunity in humans. Hc subunit، as binding domain of the toxoid is considered as immunogenic part of tetanus toxin. The THc and LTB recombinant subunits have the potential role to induce immunological memories with different longevity. The purpose of this study was to evaluate and compare the immunogenicity of THc and LTB recombinant proteins in animal model and also to evaluate their roles in immunity duration. The recombinant proteins، THc and LTB، were expressed in the transgenic host، E. Coli Bl21 DE3 using pET28a vector containing their respected genes in optimum condition. After express-ion، LTB and THc were purified from insoluble and soluble phases، respectively. Then، their purity was confirmed by SDS-PAGE gel. To evaluate their immuno-genicity، these proteins were injected into mice and the antibody titer were evaluated and compared by ELISA technique. SDS-PAGE results showed overexpressed levels of the proteins under study. Immunity assessment revealed that in the same condition of immunity the THc subunit produces a higher antibody titer in comparison with the LTB subunit. ِDiscussion & The first step in creating a strong and long-lasting immune-ological memory is the induction of high titer of antibody. Thus، the difference in antibody titer may be related to memory cells lifetime in the immunized mice.