Immunoproteomic Assay of Antigenic Surface Proteins in Streptococcus equi ssp. zooepidemicus

Streptococcus equi ssp. zooepidemicus (S. zooepidemicus) is a zoonotic pathogen with worldwide distribution. Lacking suitable vaccine and virulent maker is still bottleneck to control this infection. An immunoproteomic approach has been used to screen the membrane-associated and cell wall-associated proteins of S. zooepidemicus isolate in China CY to discover vaccine candidate antigens and therapeutic agents. Finally, 11 membrane-associated proteins, and 13 cell wall-associated proteins were successfully identified. BLAST (www.sanger.ac.uk) results also indicated that nucleotide sequences of majority identified proteins shared high homology (>60%) with S. zooepidemicus, except for AC1-3, AC5, AC8, and AC 13. Moreover, genes for 7 of the identified proteins were detected from C Y; compared with ST 171, 3 of them (AMI, AM8 and AC11) were only found in virulent strains (CY). All of the proteins identified in this study remain not to be reported in S. zooepidemicus. Some of the proteins serve a vital role in the immune system and reproduction of host species according to available data, while the functions of the rest were seldom researched.