Whole proteome screening to develop a potent epitope-based vaccine against Coxiella burnetii: a reverse vaccinology approach

Coxiellosis is known as a threat to human health. This study aimed to develop an epitope-based vaccine against coxiellosis using a whole proteome investigation. In this case, the whole proteome of Coxiella burnetii was collected from the database, then different assessments were performed to select immunogenic proteins. The selected proteins were used for epitopes prediction. The epitope-based vaccine was made using the best-selected epitopes and HBHA protein. The physical and chemical features, as well as secondary and tertiary structures of the developed vaccine were analyzed. The interaction between the developed vaccine and TLR4/MD2 receptor was examined using molecular docking and molecular dynamic simulation. Finally, in silico cloning, codon optimization, and immune response simulation for the developed vaccine were performed. The findings supported a stable, hydrophilic, antigenic and non-allergenic vaccine with a molecular weight equal to 59.261 kDa and 542 amino acid residues in length. The findings showed that the developed vaccine not only could dock to TRL4/MD2 receptor with an affinity of -20.9 kcal/mol and 15 hydrogen bonds, but also the protein-protein complex was stable during molecular dynamic simulation with the binding free energy of -57.9 +/- 6.9 kcal/mol. Furthermore, the optimized sequence of the developed vaccine with a CAI value of 0.97, could be cloned into the pET-21a (+) vector. Finally, The results confirmed that the developed vaccine could strongly trigger primary and secondary immune responses. Evidently, the developed vaccine can be an interesting candidate to apply.