Identification of Streptococcus equi ssp. zooepidemicus surface associated proteins by enzymatic shaving

Streptococcus equi ssp. zooepidemicus (Streptococcus zooepidemicus, SEZ) is responsible for a wide variety of infections in many species. Attempts to control the infection caused by this agent are hampered by a lack of effective vaccines and useful diagnostic kits. Surface proteins of bacterial species are usually involved in interaction with host and hopefully act as biomarkers for serodiagnosis and subunit vaccine components. In this study, the surface proteins of SEZ C55138 strain were systematically identified by surface shaving with trypsin and a total of 20 surface associated proteins were found. Further analysis of five selected novel proteins (SzM, FBP, SAP, CSP and 5′-Nu) revealed that they all expressed in vivo and their recombinant derived proteins could be reactive with convalescent sera. These identified immunogenic surface proteins have potential as SEZ vaccine candidates and diagnostic markers.