Figure 3.

Showing the role of ExoA and pyoverdin in pathogenesis of P. aeruginosa in keratitis. The virulence factor ExoA’s interaction with pyoverdin enhances the progression and proliferation of keratitis on the ocular surface. P. aeruginosa produces Exotoxin A (ExoA), a strong exotoxin that suppresses protein synthesis in host cells by ADP-ribosylation of elongation factor 2. Pyroverdine, an iron-scavenging siderophore that regulates ExoA production and pyoverdine itself, is released by the bacterium. An isogenic P. aeruginosa mutant (∆pvdE, deficient in pyoverdin synthesis) showed better adhesion to human cultured corneal epithelial cells (HCEC), but it was unable to cause keratitis. Therefore, pyoverdin and its associated ExoA are essential for the development and spread of P. aeruginosa keratitis on the surface of the eye.