Updated project metadata. 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 purified the extracellular vesicles (EVs) of S. equi ATCC 39506 and evaluated them as vaccine candidates against S. equi infections in mice. Through immunization in an animal model and immunoprecipitation-mass spectrometry, we evaluated EV as vaccine candidates against S. equi infections and identified novel immunogenic proteins.