In silico Studies for Comparison of FliCs from Salmonella typhimorium, Pseudomonas aeruginosa, and Escherichia coli and their Implication as an Adjuvant

An increasing number of studies have demonstrated the effectiveness of flagellin (FliC) as an adjuvant. In this study, FliC(s) from Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa, and Escherichia coli were compared. In silico studies were designed to determine physicochemical parameters of FliC from different bacteria. The fliC gene corresponding to best model was amplified, cloned and expressed into pET28a vector. Bioactivity of the protein was determined by measurement of the interleukin 8 in cell culture after interaction of FliC with TLR-5. According to in silico studies, FliC of S. typhimorium has a higher quality of physiochemical properties, and more affinity to TLR-5 than the other FliCs. SDS-PAGE showed an approximately 54 kDa band, and Western blot confirmed the presence of recombinant protein. IL-8 was expressed significantly in cell culture under S. typhimorium FliC induction. Considering side effects, and costs of conventional adjuvants, FliC can be introduced as a potent natural adjuvant in future studies. In silico studies can save time and cost, and screen potent proteins.