This laboratory has focused its efforts on molecular mechanisms of mycoplasmal pathogenesis for many years. To this end, we have developed genetic systems that can be used to identify and analyze virulence factors (Tn4001, integrative vectors, reporter constructs and cloning systems). We have also identified and studied membrane activities that might be involved in virulence (nucleases and hemolysins). Our more recent studies in mycoplasmas have focused on the cilium adhesin of Mycoplasma hyopneumoniae, genomic sequencing of Mycoplasma hyopneumoniae, and the development of recombinant vaccines against M. hyopneumoniae. We have also constructed and validated a microarray for M. hyopneumoniae to study transcriptional responses to environmental changes and better understand gene regulation. Recently, we have also developed projects with other bacterial pathogens important either to animal health or food safety. Most notably of these are ongoing studies on the persistence of E. coli O157:H7 in the ruminant focusing on biofilm development, the persistence of Salmonella enteritidis in chickens, and transcription regulation of Listeria monocytogenes and E. coli O157:H7. The latter involves the construction and validation of microarrays for these two pathogens.