Pathology and Pathogenesis of Yersinia pestis.

Various types of animal models of plague have been developed, including mice, rats, guinea pigs, and nonhuman primates. Studies have indicated that rodent and nonhuman primate models of pneumonic plague closely resemble the human disease and that the pathologic changes that occur during bubonic plague are very similar in rodents, nonhuman primates, and humans. In this section, the pathological changes caused by Y. pestis in different animal models are described. The bacterium Y. pestis causes deadly plague, whereas the other two closely related enteropathogenic Yersinia species merely cause limited gastrointestinal manifestations. Y. pestis has unique virulence mechanisms that enable it to be a successful flea-borne and highly virulent pathogen. Massive gene losses and inactivation play important roles, as well as the gene acquisitions, in the evolution process of this pathogen. Here, we summarized several newly acquired features of Y. pestis, including the unique lipid A modification, biofilm formation ability, and loss of adhesions for enteric colonization that are realized by gene inactivation and plasminogen activator and F1 capsular that are realized by gene acquisition, which contribute to the unique transmission and pathogenesis of Y. pestis.