Cloning and analysis of the conserved regions in the capsular polysaccharides synthesis locus of Streptococcus suis

Abstract:

Abstract:［Objective］ To learn about the function and gene phylogenetic relationship of the conserved regions in capsular polysaccharides synthesis (CPS) locus，［Methods］ based on the CPS locus sequence of Streptococcus suis serotype 1，2， 7 and 9 and the results to the cross-hybridization experiments，the CPS locus of Streptococcus suis was hypothesized as cassette-like structure which is similar to Streptococcus pneumoniae． PCR，sequencing and southern blotting was used to certify the hypothesis． ［Results］ The CPS locus of Streptococcus suis was cassette-like structure． The 5'-end of the CPS locus contained 4 regulatory genes which are highly similar in all the serotypes． The flanking genes of the CPS locus are conservative． The flanking gene aroA，which is at the downstream to the CPS locus，was selected as the objective gene to develop the PCR to amplify the serotype-specific regions． The orfY、orfX、cpsA、cpsB、cpsC、cpsD and aroA are conserved with high sequence identity in different serotypes．