38th Annual Meeting of the Society for Invertebrate Pathology

Despite their importance, little is known about the origins of emerging human pathogens. We argue that given the age and predominance of bacteria-invertebrate interactions, that these pathogens have 'learned' their pathogenic skills in invertebrates rather than vertebrates. Thus the current emphasis on sequencing pathogens of man is only giving us a tiny glimpse of the available net 'pathosphere' (the global pool of virulence factors). We will discuss the communalities of the vertebrate and invertebrate immune systems and argue that once bacteria can overcome the invertebrate immune system, they can more readily overcome the vertebrate immune system. We will also examine specific cases (Yersinia, Bacillus cereus and Photorhabdus) where putative arthropod vectors have facilitated the leap from invertebrates to vertebrates. We predict that as we learn more about the natural history of pathogens outside of man, that the origin of pathogenicity within invertebrates and its vectoring to man will be common.