Rosqvist R, Bölin I, Wolf-Watz H
Department of Cell and Microbiology, Swedish Defence Research Establishment, Umeå, Sweden.
Infect Immun. 1988 Aug;56(8):2139-43. doi: 10.1128/iai.56.8.2139-2143.1988.
Virulence plasmid-containing cells of Yersinia pseudotuberculosis had the ability to inhibit phagocytosis by mouse peritoneal macrophages cultured in vitro, but cells of its plasmid-cured derivative did not. Inhibition was most pronounced when the pathogen was incubated under Ca2+-deficient conditions, which allowed a high level of expression of outer membrane proteins (Yops). The addition of 2.5 mM Ca2+ to the growth medium reduced the degree of inhibition by the pathogen, but it was still significantly higher than that of the plasmid-cured strain. An avirulent mutant strain, from which the entire yopH gene was deleted, was impaired in its phagocytosis inhibition ability. This mutant could be trans-complemented by the yopH+ gene back to the wild-type phenotype with respect to virulence, as well as the ability to inhibit phagocytosis, demonstrating that the ability to inhibit phagocytosis is an important virulence function. The mutant strain was still cytotoxic for HeLa cells, indicating that inhibition of phagocytosis can be genetically separated from the ability to cause a cytotoxic effect.
含有毒力质粒的假结核耶尔森氏菌细胞能够抑制体外培养的小鼠腹腔巨噬细胞的吞噬作用，但其质粒消除衍生物的细胞则不能。当病原体在缺钙条件下孵育时，抑制作用最为明显，这种条件可使外膜蛋白（Yops）高水平表达。在生长培养基中添加2.5 mM钙离子可降低病原体的抑制程度，但仍显著高于质粒消除菌株。一个缺失整个yopH基因的无毒突变菌株，其吞噬作用抑制能力受损。该突变体可通过yopH +基因反式互补回到野生型毒力表型，以及抑制吞噬作用的能力，这表明抑制吞噬作用的能力是一种重要的毒力功能。该突变菌株对HeLa细胞仍具有细胞毒性，表明吞噬作用的抑制可与引起细胞毒性效应的能力在遗传上分离。
