WANG Xiaoning and coworkers at South China University of Technology have made a

breakthrough in understanding a signal-transduction system that is crucial for the

virulence of highly invasive Streptococcus suis. The finding was published in the recent

issue of Public Library of Science One (PLoS One). By comparing genomic sequences of

various bacterial strains, researchers identified a putative pathogenic island that is unique

to the two SS2 strains isolated from Chinese patients. WANG and co-workers found that,

unlike their wild-type counterparts, SalK/SalR-lacking bacteria were not capable of

colonizing, and thereby infecting piglet tissues. By comparing gene expression in wild-type

and SalK/SalR-lacking bacteria, researchers identified the genes that were down-regulated

in the mutant, which could serve as leads for further characterization of SS2 virulence.