Vaccinomic Design of an Epitope-Based Fusion Protein Against Leishmania infantum Through Whole-Proteome Screening

Introduction: Visceral leishmaniasis is a common disease between animals and humans which is primarily induced by Leishmania infantum.
Objective: This research was conducted to engineer a recombinant vaccine against this disease.
Material & methods: To achieve this, the whole proteome of Leishmania infantum was analyzed to identify the most antigenic proteins; the screened proteins were then used for predicting different type of epitopes. For the creation of a recombinant vaccine, the predicted epitopes were linked to the RpfE protein using appropriate linkers. To assess the potency of the designed vaccine, various evaluations including physicochemical parameters, various structures and refinement of three-dimensional structure were performed using reliable and trustable tools. Additionally, the protein-protein docking of our recombinant vaccine and the its receptor was investigated using HDOCK server and the docking result was evaluated by molecular dynamics. Finally, to assess expression of the recombinant vaccine in Escherichia coli BL21, its nucleotide sequence was optimized and cloned into pET21a (+).
Results: Our results confirmed that the recombinant vaccine was a robust protein with molecular mass of 49.39 kDa which contain 83.51 % random coil. Furthermore, our findings confirmed that the recombinant vaccine could successfully and stably interact with the TLR4 receptor via the RpfE domain with a docking score of 308 and through five hydrogen bonds. Moreover, it was confirmed that the nucleotide sequence of the recombinant vaccine was optimized with CAI =1 and the optimized sequence with 1401 nucleotides in length was successfully cloned into cleavable site of pET21a (+) vector.
Conclusion: Finally, the current study's findings confirmed that the recombinant vaccine could be a suggestable vaccine to prevent Leishmania infantum.