In-silico design and production of a novel antigenic chimeric Shigella IpaB fused to C-terminal of Clostridium perfringens enterotoxin.

The emergence of antibiotic-resistant phenotypes in Shigella serotypes and the high mortality rate, approximately one million dead annually, in affected patients announce a global demand for an effective serotype-independent vaccine against Shigella. This study aims to design, express, and purify a novel chimeric protein, as a serotype-independent vaccine candidate against Shigella containing full-length Shigella invasion plasmid antigen B (IpaB) and a C-terminal fragment (residues 194-319) of Clostridium perfringens enterotoxin (C-CPE) as a mucosal adjuvant. Several online databases and bioinformatics software were utilized to design the chimeric protein and the relative recombinant gene. The recombinant gene encoding IpaB-CPE was synthesized, cloned into pACYCDuet-1 expression vector, and transferred to E. coli Bl21 (DE3) cells. IpaB-CPE was then expressed in auto-induction medium, purified and characterized using MALDI-TOF-TOF mass spectrometry. Followed by subcutaneous injection of the purified IpaB-CPE to BALB/c mice, antigenicity of this chimeric protein was determined through performing dot-blot immunoassay on nitrocellulose membrane using mice sera. The outcomes of this study show the successful design, efficient expression, and purification of IpaB-CPE divalent chimeric protein under mentioned conditions. The obtained results also demonstrate the intrinsic antigenic property of IpaB-CPE.