Streptococcus suis infection: An emerging/reemerging challenge of bacterial infectious diseases?

Feng, Youjun; Zhang, Huimin; Wu, Zuowei; Wang, Shihua; Cao, Min; Hu, Dan; Wang, Changjun

ethod of bacterial cell density-dependent communication, using secreted chemical molecules (like the auto-inducer) as a form of "language". The luxS gene product is the synthetase of autoinducer 2 (AI-2) that is required for interspecies communication. Recently, we and Lu's group both defined a functional LuxS member present in Chinese isolates of S. suis 2, and demonstrated its relevance to bacterial virulence. 139, 140 Zhang et al. identified that IgA1 protease, an immune-dominant antigen, is necessary for full virulence of S. suis 2. 138 Additionally, Gruening et al. 146 proved that the arginine deiminase system (ADS), encoded by arcABC operon, is necessary for S. suis survival in acidic stress, indicating its possibility of correlating with bacterial successful infection. Very recently, it was discovered that the adenosine synthase functions as an effector in evasion of PMNs-mediated innate immunity 147 . It might suggest possibility that cyclic AMP (cAMP)-dependent signaling is linked to streptococcal infectivity. Given the fact that CadD enzyme, cAMP deaminase from Leptospira, 148 can quench cAMP-dependent signaling, it would be of interest to test the hypothesis that in vivo expression of CadD protein in S. suis modulate bacterial pathogenesis or not?