Yersinia pestis resists predation by Acanthamoeba castellanii and exhibits prolonged intracellular survival.

This study investigates the interaction between Y. pestis and the ubiquitous soil free-living amoeba (FLA), Acanthamoeba castellanii, to assess if the bacterium can survive within soil amoeba and whether intracellular mechanisms are conserved between infection of mammalian macrophages and soil amoeba. The results demonstrate that during co-culture with amoeba, representative Y. pestis strains of epidemic biovars Mediaevalis, Orientalis and Antiqua are phagocytized and able to survive within amoeba for at least five days. Key Y. pestis determinants of the intracellular interaction of Y. pestis and phagocytic macrophages, PhoP and the type three secretion system (T3SS), were then tested for their roles in the Y. pestis-amoeba interaction. Consistent with a requirement for the PhoP transcriptional activator in intracellular survival of Y. pestis in macrophages, a PhoP mutant is unable to survive when co-cultured with amoeba. Additionally, induction of the T3SS blocks phagocytic uptake of Y. pestis by amoeba, similar to that which occurs during macrophage infection. Electron microscopy revealed that in A. castellanii, Y. pestis resides intact, within spacious vacuoles which were characterized using lysosomal trackers as being separated from the lysosomal compartment. This evidence for prolonged survival and subversion of intracellular digestion of Y. pestis within a FLA suggest that protozoa may serve as a protective soil reservoir for Y. pestis.ImportanceYersinia pestis is a re-...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research