This week in PLoS Pathogens, researchers at the University of California, Berkeley, "provide the first direct evidence that a pathogenicity island-encoded sRNA, IsrM, is important for Salmonella invasion of epithelial cells, intracellular replication inside macrophages, and virulence and colonization in mice." The team shows that Salmonella in which isrM has been deleted "is defective in bacteria invasion," and as a result, suggest "sRNAs may represent a dis