The invention relates to Streptococcus suis infection in pigs, vaccines directed against those infections and tests for diagnosing Streptococcus suis infections. The invention provides an isolated or recombinant nucleic acid encoding a capsular gene cluster of Streptococcus suis or a gene or gene fragment derivated thereof. The invention further provides a nucleic acid probe or primer allowing species or serotype-specific detection of Streptococcus suis. The invention also provides a Streptococcus suis antigen and vaccine derived thereof.
1. A composition, comprising:
a Streptococcus suis serotype 2 knockout mutant wherein the knockout mutation is in the capsular polysaccharide (cps) gene cluster as set forth in SEQ ID NO: 9, wherein the knockout mutation is in the cpsB gene encoding the cpsB protein as set forth in SEQ ID NO: 13, the cpsE gene encoding the cpsE protein as set for in SEQ ID NO:16, or the cpsF gene encoding the cpsF protein as set forth in SEQ ID NO:17 or a combination thereof, the knockout mutation causing a deficiency in cellular capsular expression, and
a pharmaceutically acceptable carrier or adjuvant.
2. The composition of claim 1 , wherein said Streptococcus suis serotype 2 knockout mutant is capable of surviving in an immune-competent host.
3. The composition of claim 2 , wherein said Streptococcus suis serotype 2 knockout mutant is capable of surviving at least 4-5 days in said immune-competent host.
4. The composition of claim 1 , wherein said Streptococcus suis serotype 2 knockout mutant expresses a Streptococcus virulence factor or antigenic determinant.
5. The composition of claim 1 , wherein said Streptococcus suis serotype 2 knockout mutant expresses a non-Streptococcus protein.
6. The composition of claim 5 , wherein said non-Streptococcus protein has been derived from a pathogen.
7. The composition of claim 2 , wherein said Streptococcus suis has been produced by homologous recombination.
8. The composition of claim 2 , wherein said Streptococcus suis is capable of surviving at least 8-10 days in said host.
9. The composition of claim 1 , wherein the knockout mutation is in the cpsB gene encoding the cpsB protein as set forth in SEQ ID NO: 13.
10. The composition of claim 1 , wherein the knockout mutation is in the cpsE gene encoding the cpsE protein as set forth in SEQ ID NO:16.
11. The composition of claim 1 , wherein the knockout mutation is in the cpsF gene encoding the cpsF protein as set forth in SEQ ID NO:17.