Properties of PASP: a Pseudomonas protease capable of mediating corneal erosions.

PURPOSE To analyze PASP in terms of its gene distribution and expression, its corneal pathologic effects, its enzymatic properties, and the protectiveness of the immune response to this protease. METHODS Twenty-five strains of P. aeruginosa were analyzed for the PASP gene and secreted protein by PCR and Western blot analysis, respectively. Active recombinant (r)PASP (10 microg/20 microL) or heat-inactivated rPASP was intrastromally injected into rabbit corneas. Pathologic changes were monitored by slit lamp examination (SLE) and histopathology. Purified rPASP was assayed for cleavage of collagens and susceptibility to TLCK. Rabbit antibody to rPASP was produced and tested for enzyme inactivation, and actively immunized rabbits were challenged by intrastromal injection of active rPASP (5 microg). RESULTS All 25 strains of P. aeruginosa analyzed were positive for the PASP gene and protein. SLE scores of eyes injected with active rPASP were significantly higher than control eyes at all postinjection times (PI; P or= 10,000) was produced, but this antibody did not protect against active rPASP challenge. CONCLUSIONS PASP is a commonly produced Pseudomonas protease that can cleave collagens and cause corneal erosions.