Howe Kevin, Salehi Sanaz, Hartford Bailey R, Brooks John P, Wills Robert, Lawrence Mark L, Karsi Attila
Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi State, MS, USA.
USDA-ARS, Genetics and Precision Agriculture Unit, Mississippi State, MS, USA.
BMC Microbiol. 2017 Apr 5;17(1):88. doi: 10.1186/s12866-017-0989-3.
Critical to the development of Salmonellosis in humans is the interaction of the bacterium with the epithelial lining of the gastrointestinal tract. Traditional scientific reasoning held type III secretion system (T3SS) as the virulence factor responsible for bacterial invasion. In this study, field-isolated Salmonella enterica serovar Kentucky and a known human pathogen Salmonella enterica serovar Typhimurium were mutated and evaluated for the invasion of human colorectal adenocarcinoma epithelial cells.
S. enterica serovar Kentucky was shown to actively invade a eukaryotic monolayer, though at a rate that was significantly lower than Typhimurium. Additionally, strains mutated for T3SS formation were less invasive than the wild-type strains, but the decrease in invasion was not significant in Kentucky.
Strains mutated for T3SS formation were able to initiate invasion of the eukaryotic monolayer to varying degrees based on strain, In the case of Kentucky, the mutated strain initiated invasion at a level that was not significantly different from the wild-type strain. A different result was observed for Typhimurium as the mutation significantly lowered the rate of invasion in comparison to the wild-type strain.
沙门氏菌病在人类中的发展，关键在于该细菌与胃肠道上皮的相互作用。传统科学推理认为III型分泌系统（T3SS）是负责细菌入侵的毒力因子。在本研究中，对从野外分离的肠炎沙门氏菌肯塔基血清型菌株以及已知的人类病原体肠炎沙门氏菌鼠伤寒血清型菌株进行突变，并评估它们对人结肠腺癌上皮细胞的侵袭情况。
肠炎沙门氏菌肯塔基血清型菌株显示出能主动侵袭真核细胞单层，不过其侵袭速率显著低于鼠伤寒血清型菌株。此外，因T3SS形成而发生突变的菌株比野生型菌株的侵袭性更低，但在肯塔基血清型菌株中侵袭性的降低并不显著。
因T3SS形成而发生突变的菌株能够根据菌株的不同，在不同程度上启动对真核细胞单层的侵袭。就肯塔基血清型菌株而言，突变菌株启动侵袭的水平与野生型菌株没有显著差异。而对于鼠伤寒血清型菌株则观察到不同的结果，与野生型菌株相比，突变显著降低了其侵袭速率。
