Chatti A, Daghfous D, Landoulsi A
Unité de biochimie des lipides et interaction des macromolécules en biologie, 03/UR/0902, laboratoire de biochimie et biologie moléculaire, département des sciences de la vie, faculté des sciences de Bizerte, Zarzouna 7021, Tunisia.
Pathol Biol (Paris). 2008 May;56(3):121-4. doi: 10.1016/j.patbio.2007.09.027. Epub 2008 Jan 4.
Numerous studies have shown that Salmonella typhimurium dam mutants are highly attenuated for virulence in mice. In vivo studies have also shown that, on oral and intraperitoneal administration, low number of these mutants is able to colonize and persist in target organs. So, they must sense and overcome a myriad of host killing mechanisms. Our goal was to evaluate the effect of in vivo passage, in mice, on S. typhimurium dam mutant virulence and fitness. Swiss albino mice were used for the determination of LD50 and enumeration of bacteria recovered from liver eight days postinfection. Our results indicate that LD50 values of re-isolated mutants were at least two to three-fold lower than those of control strains. Strains re-isolated from liver showed decreased in vitro sensitivity toward sodium deoxycholate and H(2)O(2) than control strains. In addition, the number of re-isolated mutants colonizing spleen and liver was relatively higher than control strains. According to these results, we suggest that persistence of S. typhimurium dam mutants within target organs can increase their in vivo virulence in mice.
众多研究表明，鼠伤寒沙门氏菌dam突变体在小鼠体内的毒力大幅减弱。体内研究还表明，经口服和腹腔注射后，少量的这些突变体能够在靶器官中定殖并持续存在。因此，它们必须感知并克服众多宿主杀伤机制。我们的目标是评估在小鼠体内传代对鼠伤寒沙门氏菌dam突变体毒力和适应性的影响。使用瑞士白化小鼠测定半数致死剂量（LD50），并在感染后八天对从肝脏中回收的细菌进行计数。我们的结果表明，重新分离的突变体的LD50值比对照菌株至少低两到三倍。从肝脏中重新分离的菌株在体外对脱氧胆酸钠和H₂O₂的敏感性低于对照菌株。此外，定殖于脾脏和肝脏的重新分离的突变体数量相对高于对照菌株。根据这些结果，我们认为鼠伤寒沙门氏菌dam突变体在靶器官内的持续存在可增加其在小鼠体内的毒力。
