Growth and Virulence of Typhimurium Mutants Deficient in Iron Uptake.

The present study investigated the effects of iron, iron chelators, and mutations of or genes on the growth and virulence of Typhimurium Results indicated that organic iron (ferric citrate and ferrous-l-ascorbate) supported better growth of compared to inorganic iron. Among tested chelators, 2,2'-bipyridyl at 500 μM showed the highest inhibition of growth with 5 μM ferrous sulfate. Deletion of genes ( and ) in the iron uptake system attenuated invasion of Caco-2 cells and its ability to damage the epithelial monolayer. The expression of all tested host genes in Caco-2 was not affected under the iron-poor condition. However, claudin 3, tight junction protein 1, tumor necrosis factor α (TNF-α), and interleukin-8 (IL-8) were altered under the iron-rich condition depending on individual mutations. In , a significant down-regulation of ferritin 1 expression was observed when the nematode was infected by the wild-type (WT) strain.