Described are Streptococcus suis infections in pigs, vaccines directed against those infections and tests for diagnosing S. suis infections. Provided is an isolated or recombinant nucleic acid encoding a capsular gene cluster of S. suis or a gene or gene fragment derived therefrom. Further provided is a nucleic acid probe or primer allowing species or serotype-specific detection of S. suis . Also provided is a Streptococcus suis antigen and vaccine derived therefrom.
1. A recombinant Streptococcus suis serotype 1 knockout mutant, wherein the knockout mutation is in the capsular polysaccharide (cps) gene cluster as set forth in SEQ ID NO: 29, wherein the knockout mutation is in
the cps1E gene encoding the cps1E protein as set forth in SEQ ID NO:30,
the cps1F gene encoding the cps1F protein as set forth in SEQ ID NO:31, or
a combination thereof, and
wherein the knockout mutant is deficient in capsular expression.
2. A composition comprising the recombinant Streptococcus suis knockout mutant of claim 1 .
3. The composition of claim 2 , wherein the Streptococcus knockout mutant is able to survive in an immune-competent host.
4. The composition of claim 3 , wherein the Streptococcus knockout mutant is able to survive at least 4-5 days in the immune-competent host.
5. The composition of claim 2 , wherein the Streptococcus knockout mutant expresses a Streptococcus virulence factor or antigenic determinant.
6. The composition of claim 2 , wherein the Streptococcus knockout mutant expresses a non- Streptococcus protein.
7. The composition of claim 6 wherein the non- Streptococcus protein is from a pathogen.
8. A method for generating an immune response against a Streptococcus suis antigen in a subject, the method comprising:
inoculating the subject with the composition of claim 2 .
9. The recombinant Streptococcus knockout mutant of claim 1 that has been produced by homologous recombination.
10. The composition of claim 3 , wherein the recombinant Streptococcus knockout mutant is able to survive at least 8-10 days in the host.