Pathogens and hosts: The dance is the same, the couples are different

History was made December 9–11, 1999, at the Beckman Center in Irvine, CA with the National Academy of Sciences colloquium “Virulence and Defense in Host–Pathogen Interactions: Common Features Between Plants and Animals.” This was the first colloquium dedicated to the discussion of virulence mechanisms shared by plant and animal pathogens and defense mechanisms shared by plants and animals. It has become clear from the commonality in microbial virulence mechanisms and the occurrence of similar innate resistance systems in animals and plants that all of these mechanisms have an ancient and intertwined history. It also is becoming increasingly evident that susceptibility or resistance to disease involves subtle and highly specific exchanges of molecular signals between pathogens and their hosts and that understanding them can provide new approaches to controlling diseases. The colloquium provided a remarkable closure to a century that began with only a primitive understanding of the microorganisms that cause disease in plants and animals. Indeed, it was only because of breakthroughs of the past decade in understanding the molecular biology of microbial virulence and eukaryote defense that the need to bring the plant and …