Characterization of a nonencapsulated mutant of Streptococcus suis serotype 2 and evaluation of its protective abilities in a mouse model

Abstract:

The biological function of a formerly constructed nonencapsuled mutant Δcps2B from 05ZYH33 was characterized, and its protection against infection was evaluated. We found that Δcps2B have reduced ability to form long chain capsule polysaccharide and no longer agglutinated with the specific anti-capsular serum. The Δcps2B could be cleared more easily by the whole blood of human and piglet, while the capacity of adhesion to epithelial cells increased greatly. Animal infection experiment demonstrated that the Δcps2B protect mice from lethal challenge with S. suis 2. These observations indicate that the capsule plays an essential role in the pathogenesis and invasiveness of S. suis 2.

Key words:Streptococcus suis serotype 2;Capsular polysaccharide;Biological characteristics;Immunoprotection