Fusion of Cholera toxin B subunit (ctxB) with Shigella dysenteriae type I toxin B subunit (stxB), Cloning and Expression that in E. coli

Shiga toxin (STx) is the main virulence factor in Shigella Dysenteriae type I and is composed of an enzymatic subunit STxA monomer and a receptor-binding STxB homopentamer. Shigella toxin B subunit (STxB) is a non-toxic homopentameric protein responsible for toxin binding and internalization into target cells by interacting with glycolipid (Gb3). Cholera toxin B subunit (CTB) has been known as a mucosal adjuvant for vaccines and genetic fusions of CTB with several hetroantigens such as stxB and can increase humoral and mucosal immunity response. In this study، after primer designing، the ctxB and stxB genes were amplified by PCR and cloned into the pGEM-T vector. The stxB gene with a nonfurin linker was fused to the ctB gene in the pGEM vector via the restriction enzyme method and thereafter the fused genes of ctB-stxB were subcloned in the pET28a (+) as an expression vector. The expressed chimeric protein was induced with IPTG and evaluated via the SDS. PAGE and Western blot techniques. The pET28a (+) /ctxB-stxB expression vector was confirmed by endonuclease digestion، PCR، and sequence analysis. The CTB-STB fusion protein was confirmed by the SDS-PAGE and Western-blot. The CTB-STB recombinant protein can be used as a new and desirable mucosal vaccine for Shigella Dysenteriae type I.