Hackett J, Kotlarski I, Mathan V, Francki K, Rowley D
J Infect Dis. 1986 Jun;153(6):1119-25. doi: 10.1093/infdis/153.6.1119.
We cured a strain of Salmonella typhimurium of its cryptic plasmid and confirmed that orally administered cured strains lost virulence for mice. Loss of the cryptic plasmid rendered the S. typhimurium strain sensitive to the bactericidal action of normal human serum. However, loss of the plasmid did not change the ability of the strain to associate with HeLa cells in tissue culture. Furthermore, when administered orally to mice, both the plasmid-containing and plasmid-free strains invaded the Peyer's patches of the small intestine to the same extent, and both were capable of inducing resistance to oral challenge with virulent S. typhimurium. When injected intraperitoneally, the cured strain was eliminated rapidly, whereas the parental strain persisted. We also showed that the cured strain did not contain a plasmid copy in the chromosome. We propose that although the plasmid-cured strain of S. typhimurium is able to colonize Peyer's patches, it cannot survive when administered intraperitoneally because it is susceptible to elimination by macrophages.
我们去除了一株鼠伤寒沙门氏菌的隐蔽质粒，并证实口服去除质粒的菌株对小鼠失去了毒力。隐蔽质粒的缺失使鼠伤寒沙门氏菌菌株对正常人血清的杀菌作用敏感。然而，质粒的缺失并未改变该菌株在组织培养中与HeLa细胞结合的能力。此外，当口服给小鼠时，含质粒和不含质粒的菌株对小肠派尔集合淋巴结的侵袭程度相同，并且两者都能够诱导对强毒鼠伤寒沙门氏菌口服攻击的抵抗力。当腹腔注射时，去除质粒的菌株迅速被清除，而亲本菌株则持续存在。我们还表明，去除质粒的菌株在染色体中不含有质粒拷贝。我们提出，尽管鼠伤寒沙门氏菌的质粒去除菌株能够在派尔集合淋巴结中定殖，但当腹腔注射时它无法存活，因为它易被巨噬细胞清除。
