Survival and growth of Yersinia pestis within macrophages and an effect of the loss of the 47-megadalton plasmid on growth in macrophages

Abstract

The survival and growth of Yersinia pestis cells within mouse peritoneal cavities and within mouse peritoneal macrophages maintained in vitro was examined. Two strains were used which differed only in that one (KIM) contained the 47-megadalton plasmid associated with virulence and the second (KIM1) lacked this plasmid. The KIM cells, but not the KIM1 cells, acquired some resistance to phagocytosis during growth at 37°C which was not evident when cells were grown at 26°C. Whether previously grown at 26 or 37°C, however, a substantial portion of the cells of either strain which were phagocytized were apparently killed after phagocytosis in vivo, although this was not observed in vitro. KIM cells which survived phagocytosis proliferated within macrophages in vivo, but no increase in viable cells was seen with the KIM1 cells. Growth of the KIM1 cells within macrophages in vitro required that a complex supportive medium be used in which the bacteria could have grown if extracellular. This was not the case for the KIM cells which proliferated within macrophages supported in medium not permissive to bacterial growth. After phagocytosis of cells of either strain by macrophages maintained in vitro, phagolysosome formation occurred normally, as shown by the acridine orange dye staining technique. KIM and KIM1 cells were equally sensitive to hydrogen peroxide and superoxide anion, although the sensitivity in each case varied with growth temperature. The oxidative burst, as determined by the luminol chemiluminescence assay, was low when compared with that seen after phagocytosis of Escherichia coli cells. Chemiluminescence after phagocytosis of yeast cells by macrophages which had engulfed KIM or KIMI was also low. We conclude that survival within macrophages is substantially independent of the 47-megadalton plasmid and may be a consequence, as least in part, of blockage of the oxidative burst or rapid removal of the oxidizing compounds formed. The 47-megadalton plasmid is apparently required for subsequent proliferation within the macrophage.

Yersinia pestisCan Reside in Autophagosomes and Avoid Xenophagy in Murine Macrophages by Preventing Vacuole Acidification

“…Y. pestis is able to survive and replicate in murine macrophages in vitro (5,6,18,35,36,44) and in vivo (23) and is therefore classified as a facultative intracellular pathogen. Microscopic examination of tissues of animals experimentally infected with Y. pestis has shown the presence of plague bacilli inside macrophages (11,23,25,50).…”

“…Early work on the trafficking of Y. pestis-containing vacuoles (YCVs) in primary murine macrophages yielded evidence that YCVs fuse with lysosomes (6,45). It was therefore suggested that Y. pestis survives in a phagolysosome (45).…”

Yersinia pestis and host macrophages: immunodeficiency of mouse macrophages induced by YscW

“…12,13 Further, in vivo studies showed that, in the early steps of Y. pestis infection, plague bacilli are predominantly detected in the macrophage population. 14,15 The infected macrophages provide a protected environment in which the pathogens can proliferate and synthesize their capsular and other virulence determinants, which enable the bacteria to acquire resistance to phagocytosis and to rapidly multiply outside of the host cells, once released into the extracellular environment. It is anticipated that the study of the interaction between Y. pestis and macrophages will lead to better overall understanding of how Yersinia subverts the host immune response.…”

Characteristics and Pathogenicity of Non‐Melibiose‐Fermenting Strains of Yersinia pseudotuberculosis O3

“…Resistance to phagocytosis is an important factor in the pathogenicity of Yersinia organisms; the existence of this factor stimulates infectivity and this brings about an infectious disease called yersiniosis (38)(39)(40)(41)53). It has been shown that the resistance of Yersinia organisms to phagocytosis depends on outer-membrane proteins encoded by virulence plasmids (6,7,10,36,47). When Yersinia organisms harboring virulence plasmids are incubated with macrophages taken from the mouse peritoneal cavity, growth of the bacteria stops for a while.…”

“…When Yersinia organisms harboring virulence plasmids are incubated with macrophages taken from the mouse peritoneal cavity, growth of the bacteria stops for a while. The bacteria resist phagocytosis by macrophages by secreting outer-membrane proteins and begin to multiply as soon as the activity of phagocytosis by macrophages decreases (10,36,43,44). However, the bacteria which do not secrete outer-membrane proteins resulting from a loss of plasmids cannot resist phagocytosis and finally loose their infectivity (10,36,43,44).…”