AVIRULENCE OF A PSEUDOMONAS-AERUGINOSA ALGC MUTANT IN A BURNED-MOUSE MODEL OF INFECTION

The virulence of wild-type Pseudomonas aeruginosa PAO1 and that of a g enetically defined algC mutant, PAO1 algC::tet, were compared in a bur ned-mouse model of infection. Unlike PAO1, PAO1 algC::tet was avirulen t, grew less well in the eschar, and did not disseminate to the liver of challenged animals. We have previously shown that the P. aeruginosa algC gene is required for biosynthesis of alginate and lipopolysaccha ride (M. J. Coyne, Jr., K. S. Russell, C. L. Coyle, and J. B. Goldberg , J. Bacteriol. 176:3500-3507, 1994). In order to determine whether th e alginate or lipopolysaccharide (LPS) defect was responsible for the avirulence of this strain, we constructed a strain with a mutation in an alginate-specific gene, algD. PAO1-algD was virulent in the burned- mouse model, thus implicating the LPS defect in PAO1 algC::tet as the relevant alteration responsible for the avirulence of this strain.