Expression of in vivo-inducible Salmonella enterica promoters during infection of Caenorhabditis elegans

In vitro mimicking of the stimuli controlling in vivo-inducible bacterial promoters during infection of the host can be complex. Therefore, the use of the nematode Caenorhabditis elegans was evaluated, as a surrogate host to examine the expression of Salmonella enterica promoters. Green fluorescent protein (GFP+) was put under the control of the promoters of the pagC, mgtB, sseA, pgtE and fur genes of S. enterica. After infection of C. elegans with an S. enterica serovar Typhimurium vaccine strain expressing these constructs, clear bacterial expression of GFP+ was observed under the control of all five promoters, although significant expression was not always obtained in vitro. It is concluded that C. elegans constitutes a useful model system for the study of the in vivo expression of Salmonella promoters.