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 derived 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 recombinant Streptococcus suis serotype 9 knockout mutant, wherein the knockout mutant is in the capsular polysaccharide (cps) gene cluster as set forth in SEQ ID NO:37, wherein the knockout mutant is in the cps9D gene encoding the cps9D protein as set forth in SEQ ID NO:38, the cps9E gene encoding the cps9E protein as set forth in SEQ ID NO:39, the cps9F gene encoding the cps9F protein as set forth in SEQ ID NO:40, the cps9G gene encoding the cps9G protein as set forth in SEQ ID NO:41, the cps9H gene encoding the cps9H protein as set forth in SEQ ID NO:42, or a combination of any thereof, 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 said Streptococcus knockout mutant deficient in capsular expression is capable of surviving in an immune-competent host.
4. The composition of claim 3 , wherein said Streptococcus knockout mutant deficient in capsular expression is capable of surviving at least 4-5 days in said immune-competent host.
5. The composition of claim 2 , wherein said Streptococcus knockout mutant deficient in capsular expression expresses a Streptococcus virulence factor or antigenic determinant.
6. The composition of claim 2 , wherein said Streptococcus knockout mutant deficient in capsular expression expresses a non- Streptococcus protein.
7. The composition of claim 6 wherein said non- Streptococcus protein is from a pathogen.
8. The composition of claim 3 , wherein said recombinant Streptococcus knockout mutant has been produced by homologous recombination.
9. The composition of claim 3 , wherein said Streptococcus knockout mutant is capable of surviving at least at least 8-10 days in said immune-competent host.
10. The composition of claim 3 , wherein said Streptococcus knockout mutant is capable of surviving at least at least 8-10 days in said immune-competent host.
11. A method for generating an immune response against Streptococcus suis antigen in a subject, said method comprising:
inoculating the subject with the composition of claim 2 .
12. A method for controlling or eradicating a Streptococcus suis disease in a population, said method comprising:
inoculating one or more subjects in the population with the composition of claim 2 ;
testing for the presence of encapsulated Streptococcus suis strains in a sample collected from at least one subject in the population; and
isolating from the population subjects testing positive for the presence of encapsulated Streptococcus suis strains.
13. A method for controlling or eradicating a Streptococcus suis disease in a population, the method comprising:
inoculating one or more subjects in the population with the composition of claim 2 ;
testing for the presence of capsule-specific antibodies directed against Streptococcus suis strains in a sample collected from at least one subject in the population; and
isolating from the population subjects testing positive for the presence of capsule-specific antibodies directed against Streptococcus suis strains.
14. A method for controlling or eradicating a Streptococcus suis disease in a population, the method comprising:
inoculating one or more subjects in the population with the composition of claim 2 ;
selecting subjects in said population inoculated with the composition;
testing a sample collected from at least one subject in said population for the presence of encapsulated Streptococcus suis strains and/or for the presence of capsule-specific antibodies directed against Streptococcus suis strains; and
isolating from the population subjects testing positive for the presence of encapsulated Streptococcus suis strains and/or testing positive for the presence of capsule-specific antibodies directed against Streptococcus suis strains.