Genomes from all of the crucial bacterial pathogens of humans, plants and animals have now been sequenced, as have genomes from many of the important commensal, symbiotic and environmental microorganisms. Analysis of these sequences has revealed the forces that shape pathogen evolution and has brought to light unexpected aspects of pathogen biology. The finding that horizontal gene transfer and genome decay have key roles in the evolution of bacterial pathogens was particularly surprising. It has also become evident that even the definitions for 'pathogen' and 'virulence factor' need to be re-evaluated.
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We thank L. Snyder, J. Kelly, D. Baker, L. Bingle and S. Andersson for critical reading of the manuscript. We acknowledge the Biotechnology and Biological Sciences Research Council for funding numerous genomic research projects in our laboratories, and the Wellcome Trust (particularly the Wellcome Trust Sanger Institute) for facilitating bacterial genome sequencing in the United Kingdom. This article is dedicated to the memory of C. A. Hart.
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Pallen, M., Wren, B. Bacterial pathogenomics. Nature 449, 835–842 (2007). https://doi.org/10.1038/nature06248
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