@entity11769 serotype 2 is responsible for a wide variety of porcine @entity281 . In addition, it is considered a zoonotic agent. Knowledge about the virulence factors for this bacterium is limited but its polysaccharide capsule is thought to be one of the most important. Transposon mutagenesis with the self-conjugative transposon Tn916 was used to obtain acapsular mutants from the virulent @entity11769 type 2 reference strain S735. Clones were screened by colony-dot ELISA with a monoclonal antibody specific for a type 2 capsular epitope and clones that failed to react with the antibody were characterized. Two mutants, 2A and 79, having one and two Tn916 insertions respectively, were chosen for further characterization. Absence of capsule was confirmed by coagglutination, capillary precipitation and capsular reaction tests and by transmission electron microscopy. Absence of capsular polysaccharides correlated with increased hydrophobicity and phagocytosis by both @entity19 macrophages and porcine monocytes compared to the wild-type strain. Furthermore, both mutants were shown to be avirulent in @entity19 and @entity1707 models of @entity281 . Finally, mutant 2A was readily eliminated from circulation in @entity19 compared to the wild-type strain, which persisted more than 48 h in blood. Thus, isogenic mutants defective in capsule production demonstrate the importance of capsular polysaccharides as a virulence factor for @entity11769 type 2.

XXXX serotype 2 mutants deficient in capsular expression.

@entity11769 :: ('1307', 'Species') :: ['Streptococcus suis', 'S. suis'] @entity281 :: ('MESH:D007239', 'Disease') :: ['infection', 'infections'] @entity19 :: ('10090', 'Species') :: ['mice', 'murine'] @entity1707 :: ('9823', 'Species') :: ['pig']
@entity11769 :: (1307,Species) :: ['Streptococcus suis']
