Localization and Mortality in Mucoidal Strains

Example 4

Since no mortality was observed in mice injected with PGN5+mucE, it was determined whether cells of this strain might localize differently than VE2 cells within the mice post-injection. To test this, the luxCDABEG operon was used to tag each strain with bioluminescence. VE2 and PGN5+mucE both carry gentamicin resistance genes, while the plasmids used for labeling with bioluminescence required gentamicin sensitivity. Thus, the luxCDABEG operon was incorporated into the chromosome of PAO1 and PGN5, and then the pUCP20-pGm-mucE plasmid was introduced into each strain to induce alginate production and mucoidy. Intraperitoneal injection of C57BL/6 mice with bioluminescent PAO1+mucE showed either localization at the injection site or dissemination through the body, and lethality resulted in all mice injected (FIGS. 5A-5B). Conversely, localization at the injection site but no dissemination was observed with bioluminescent PGN5+mucE, and no mortality was observed in injected mice (FIGS. 5C-5D).