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 .