Protection of equines against Streptococcus equi

A vaccine for protecting equines against S. equi caused strangles which comprises an avirulent strain of S. equi 709-27 which stimulates an antibody response in the nasopharyngeal mucosa of the susceptible equine and includes an M-protein fragment with a molecular weight of about 41,000.

A method of protecting equines against virulent S. equi which comprises inoculating an equine either intranasally or orally with a strain of avirulent S. equi 709-27 which stimulates a nasopharyngeal antibody response in the nasopharyngeal mucosa of a susceptible equine.

A method of making a strain of S. equi which is avirulent for equines and usable as a vaccine for protecting equines against S. equi caused strangles comprising the following steps:

• 1. subjecting a virulent strain of S. equi to mutagenesis;
• 2. selecting a resulting nonencapsulated bacterium which provides an M-protein fragment having a molecular weight of about 41,000, which bacterium produces an S. equi antibody response in the nasopharyngeal mucosa of an S. equi susceptible equine.

A method of making a strain of S. equi which is avirulent for equines and usable as a vaccine for protecting equines against S. equi caused strangles comprising the following steps:

• 1. subjecting a virulent strain of S. equi to mutagenesis through Nitrosoguanidine;
• 2. selecting a resulting nonencapsulated bacterium which provides an M-protein fragment having a molecular weight of about 41,000, which bacterium stimulates an S. equi antibody response in the nasopharyngeal mucosa of an S. equi susceptible equine.

A vaccine against S. equi caused strangles in an equine, which vaccine stimulates a nasopharyngeal S. equi antibody response in a strangles susceptible equine comprising an avirulent strain of S. equi which stimulates an antibody response in the nasopharyngeal mucosa of the susceptible equine wherein said strain of avirulent S. equi is nonencapsulated and includes an M-protein fragment with a molecular weight of about 41,000 and the strain of avirulent S. equi is S. equi 709-27.

A vaccine against S. equi caused strangles in an equine, which vaccine stimulates a nasopharyngeal S. equi antibody response in a strangles susceptible equine comprising a strain of avirulent S. equi including an M-protein fragment with a molecular weight of about 41,000 and which can be inoculated intranasally or orally and wherein the strain avirulent S. equi is S. equi 709-27.

A vaccine for protecting equines against S. equi caused strangles which comprises an avirulent strain of S. equi which stimulates an antibody response in the nasopharyngeal mucosa of the susceptible equine which comprises an avirulent strain of S. equi formed by mutating using nitrosoguanidine a virulent strangles causing S. equi strain to render it avirulent and nonencapsulated while retaining thereon protein which provides an M-protein fragment with a molecular weight of about 41,000 which stimulates an immunological response in the form of IgG and IgA antibodies in the nasopharyngeal mucosa of an equine similar to that found in an equine which has recovered from S. equi caused strangles.

A method of protecting equines against virulent S. equi which comprises the inoculation of an equine either intranasally or orally with a strain of avirulent S. equi which is nonencapsulated and carries at least a M-protein fragment of about 41,000 mw and which is produced by the mutagenesis of a virulent strain of S. equi with Nitrosoguanidine.