In Silico Vaccine Designing Targeting the Virulence Factors of mce Operons of Mycobacterium avium subsp. Paratuberculosis

Background: Mycobacterium avium sp. paratuberculosis (MAP) causes Paratuberculosis (pTB) in domestic livestock and has also been associated with auto-immune disorders in humans. Infection leads to huge economic losses to the farmers associated with livestock production system worldwide. Currently, search to find proteins with the potential to develop as vaccine candidates against MAP is underway. Objective: In this study, we aimed to explore the immunogenicity of the proteins of mammalian cell entry (mce) operons of MAP using computational tools. Methods: Genes of mce operons of MAP strain K10 were selected and their orthologs identification was made using VFanalyzer tool. Mce proteins encoded by these operons were analyzed for their antigenicity and sub-cellular localization. Three dimensional structures for Mce proteins were predicted using Phyre2. B cell and T cell epitope analysis was done using methods available at Immune Epitope Database and Analysis Resource. The selection analysis of mce genes was also performed. Results: Eight Mce proteins were predicted with B cell and T cell epitopes. Some of them were reported with overlapping B cell and T cell epitopes. We found positively selected sites within some predicted epitopes that indicated some kind of selection pressure by immune system on these protein regions. Some predicted epitopes also had similarities with experimentally identified epitopes of Mce proteins of M. tuberculosis which further strengthened the immunogenic role of Mce proteins. Conclusion: Our findings may potentially assist in the development of effective vaccine against incurable infection due to MAP bacilli in the domestic livestock species.