On the Cover: Rapid translation of genomics data into pathogen-specific PCR assays may yield diagnostic signatures for a wide range of pathogens, including Salmonella enterica, shown in the background. The partial genome sequence and circular genome in the center represent the in silico comparative genomics approach, while the gel images highlight the pathognomonic multiplex PCR assay that was ultimately developed. See page 624 and accompanying Commentary on page 572. EM image kindly provided by Dr. Roberto La Ragione, Crown copyright 2007, reproduced with kind permission of the Veterinary Laboratories Agency (Weybridge, UK).