Fig 5.

The importance of pili and toxin in C. diphtheriae virulence in the C. elegans host model. L4-stage nematodes of strain N2 were fed on corynebacteria of NCTC13129 (Tox⁺/Spa⁺; black circles), as well as its isogenic ΔspaABC mutant lacking SpaA-type pili (gray circles) or its isogenic ΔspaABC Δtox mutant lacking SpaA-type pili and toxin (white circles). Nematode survival was observed over time. The results are presented as percentages, and statistical analysis was performed using GraphPad Prism 5.0. Asterisks indicate P values of <0.006.