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

Genomics/proteomics-based glimpse of S. suis Genomics/proteomics approaches to probe S. suis have yielded unprecedented comprehensive information/knowledge about this pathogen. 8, 39 At the time of writing this review, no less than 14 genomes of S. suis strains have been available in PubMed (http://www.ncbi.nlm.nih.gov/sites/entrez?db=gen ome&cmd=DetailsSearch&term=streptococcus+suis&save_ search=false), most of which were completed by the research groups in China (Fig. 2) . Genomic sequence analyses of S. suis showed that (1) all the sequenced genomes feature with the nearly same average GC content, ~41%, indicating slight evolutionary conservation; (2) genome size varies markedly from 1 640 446 nt (05HAS68, NZ_AARD00000000) to 2 146 229 nt (BM407, NC_012926), reflecting the genomic flexibility present in these species (Fig. 2B); (3) the number of putative protein-encoding genes is dramatically different (1559 for 05HAS68, and 1932 for BM407), suggesting that nearly 1/5-1/6 of total genes are not essential (redundant) for bacterial viability, and might confer some new/unknown functions to adapt to varied environmental niches. Functional/ comparative genomics of S. suis has defined a series of new infection/virulence-related determinants such as ArgR regulator, 40 SspA, a subtilisin-like protease, 41 CiaRH two-component regulatory system, 42 and so on.