Abstract: The present invention relates generally to molecular compounds which encode the protective M-like protein of Streptococcus equi (SeM), the amino acid compound which is thereby encoded, and compositions of matter which incorporate either the encoding compounds or the cellular components for which they encode. For instance, vaccines which utilize the amino acid compounds or vectors and cell lines useful to make the amino acid compounds described herein are subjects of the present invention. The present invention provides methods to stimulate S. equi-specific immune response in horses. It also provides diagnostic assays for Streptococcus equi.

Abstract: A new bacterial vaccine to protect susceptible equine against S. equi which causes strangles. The vaccine stimulates a nasopharyngeal immune response in a susceptible equine through the presence of antibody activity in the nasopharyngeal mucus. The vaccine is a S. equi strain which contains an M protein fragment of 41,000 mw and is adapted for administration to equine either intranasally or orally as a vaccine. There is described a new strain of S. equi (709-27), a method of making and isolating useful vaccine strain of S. equi bacteria which stimulates an antibody response in the nasopharyngeal mucosa of the susceptible equine.