Pseudomonas aeruginosa protease IV produces corneal damage and contributes to bacterial virulence

• Published in: Investigative ophthalmology & visual science Vol. 39; no. 3; pp. 662 - 665
• Main Authors: Engel, LS, Hill, JM, Moreau, JM, Green, LC, Hobden, JA, O'Callaghan, RJ
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01.03.1998; Association for Research in Vision and Ophtalmology
• Subjects: Animals; Bacterial diseases; Biological and medical sciences; Colony Count, Microbial; Cornea - drug effects; Cornea - microbiology; Cornea - pathology; Corneal Ulcer - chemically induced; Corneal Ulcer - microbiology; Corneal Ulcer - pathology; Experimental bacterial diseases and models; Eye Infections, Bacterial - chemically induced; Eye Infections, Bacterial - microbiology; Eye Infections, Bacterial - pathology; Infectious diseases; Medical sciences; Peptide Hydrolases - isolation & purification; Peptide Hydrolases - pharmacology; Pseudomonas aeruginosa - chemistry; Pseudomonas aeruginosa - enzymology; Pseudomonas aeruginosa - pathogenicity; Pseudomonas Infections - chemically induced; Pseudomonas Infections - microbiology; Pseudomonas Infections - pathology; Rabbits; Virulence; Pseudomonadales; Cornea; Keratitis; Pathogenesis; Virulence; Rabbit; Cytotoxicity; Keratopathy; Lagomorpha; Infection; Eye disease; Vertebrata; Experimental disease; Mammalia; Animal; Bacteriosis; Bacteria; Pseudomonadaceae; Pseudomonas aeruginosa
• ISSN: 0146-0404

A Pseudomonas mutant deficient in protease IV has significantly reduced virulence in experimental keratitis. In the present study, the corneal toxicity of purified protease IV and its ability to augment the virulence of protease-IV-deficient bacteria were analyzed. The toxicity of purified protease IV was determined by intrastromally injecting the exoenzyme (20-200 ng) into the cornea. The effects of protease IV on the corneal virulence of the protease-IV-deficient strain, PA103-29::Tn9, were determined by injecting eyes with 1000 CFU of log phase bacteria plus either 200 ng active purified protease IV or 200 ng heat-inactivated protease IV. Changes in ocular disease, determined by slit-lamp examination, were measured at 3, 16, 22, and 27 hours after infection. Colony-forming units per cornea were quantified at 27 hours after infection. Purified protease IV at doses from 50 to 200 ng induced epithelial defects within 3 hours of injection. Injection of 20 ng active protease IV or heat-inactivated protease IV (200 ng) had no effect on ocular tissue. Corneal virulence of the protease-IV-deficient strain was augmented by intrastromal injection with purified protease IV but not with heat-inactivated protease IV (P < or = 0.0001). Neither active nor heat-inactivated protease IV altered the growth of bacteria in the cornea (6 log units; P = 0.81). The important role of protease IV in corneal virulence was demonstrated by direct toxicity and by its ability to significantly augment the virulence of protease-IV-deficient Pseudomonas.