Comprehensive proteomics for Discovery vaccine candidates against Streptococcus equi Infections

Streptococcus equi subspecies equi (S. equi) is a major pathogen which cause strangles, a highly contagious respiratory infection, in horses and other equines.In this study, we discovered potential vaccine candidates using comprehensive proteomics and reverse vaccinology. As the initial step, we divided proteome of S. equi ATCC 39506 into whole cell lysate, secretory proteome, membrane proteome and extracellular vesicle and then, comparative proteomic analysis was performed to characterize the functional features of the proteome. Especially, extracellular vesicle of S. equi was evaluated at the first time. Total 114 potential vaccine candidates (PVCs) were selected using reverse vaccinology and knowledge based annotations. Comprehensive proteomic analysis confirmed that 60 PVCs were identified in S. equi ATCC 39506. Particularly, 32 PVCs were enriched in the EV proteome, suggesting that this cellular fraction may serve as vaccine.