Characterization of a new protective antigen of Streptococcus canis
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Streptococcus canis (S. canis), a lancefield group G streptococcus, is an opportunistic pathogen mainly found in dogs and cats. The study on pathogenesis and protective immune mechanism of S. canis is not clear. A new streptococcal protective antigen (SPA) was first identified from a genomic library of S. canis. SPA of S. canis (SPASc) contained a 1224-bp open reading frame which encoded a 407aa protein and a 34-aa signal sequence with a deduced molecular mass of 46.368 kDa. Protein analysis and BLAST result showed that SPASc was homologous to the SPA of Streptococcus. equi subsp. zooepidemicus, M protein Streptococcus. equi., and SPA of Streptococcus pyogenes. The protective response of SPASc antiserum was demonstrated by passive mouse protection. These studies suggested that SPASc might be an important component of vaccines to prevent S. canis infections.
KeywordsStreptococcal protective antigen S. canis Characterization Passive protection
The financial supports of Tianjin Natural Science Foundation (07JCYBJC16000) and the Project-sponsored by SRF for ROCS, SEM were gratefully acknowledged. We thank Dr. Wenzhi Xue of Intervet (Merrian, Kansas) and Dr. Minghao Sun of the Scripps Research Institute for proof reading the manuscript.
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