Similarity in Pathogenic Features in Lung and Peritoneal Infection by Coxiellaburnetii, Typhus Group Rickettsiae, and Chlamydiae

摘要

The basic trend of evolution, divergent development of organisms, is known to beaccompanied by the opposite trend: the appearance of secondary convergence of characteristics among phylogenetically unrelated species. In the world of pathogenic microorganisms, these trends are manifested by dissimilarity between closely related species and by similarity in interaction with the animal host by unrelated species. Both trends are especially apparent in microorganisms adapted to reside on or within specialized cells of the host, a highly specialized ecological habitat. The existence of enteroinvasive, enteropathogenic, and toxigenic serotypes of the same species, Escherichia coll, is an example of divergent evolution. On the other hand, the ability of unrelated species, such as the protozoan Toxoplasma gondii, the bacterium Mycobacterium tuberculosis, and Chlamydia to inhabit macrophage phagosomes while preventing phagosome-lysosome fusion 3 provides examples of convergent evolution of microorganisms with regard to basic determinants of pathogenicity. (JES)