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Purpose: To study antibody production to Pseudomonas aeruginosa protease IV (PIV) for immunoassay development and to assess the possible role of antibody in arresting corneal damage., Methods: Rabbits were immunized with PIV, urea-soluble recombinant PIV (rPIV), or precipitated rPIV. Antibody was analyzed by ELISA and Western blotting. Antibody-mediated inhibition of PIV activity was tested by colorimetric assay and during keratitis by slit-lamp examination of infected eyes., Results: Antibody was not produced after PIV immunization but was induced by rPIV. Rabbits immunized first with soluble and then precipitated rPIV produced high titers (log(10)) to rPIV (4.28 +/- 0.09) and significantly higher titers to PIV (3.90 +/- 0.06) compared to the other immunized groups. Antibody to rPIV reacted with PIV, but neither neutralized enzyme activity in vitro nor protected infected rabbits in vivo., Conclusions: The present study demonstrates that PIV is a virulence factor which can escape a protective immune response.

PURPOSE. The purpose of this study was to developan animal model of Serratia keratitis that is suitable to demonstratethe pathology of specific strains. METHODS. Serratia marcescens ocular strains 93-1399-1 and 94-EI-185-2,and an environmental strain (ATCC 14041) were characterized in vitro in terms of their motility, metabolic profiles, ribotypes, and protease production.The strains were then analyzed in the rabbit intrastromal injection model.Slit lamp examination (SLE) and enumeration of bacteria in the cornea wasconducted every 6 hours for 30 hours post-infection. In vivo motilitieswere analyzed by quantification of bacteria in the peripheral and centralareas of infected rabbit corneas. RESULTS. All strains were similar in their metabolic activity and productionof extracellular proteases. The ocular isolates were distinct from the environmentalstrain in their ribotyping patterns and in their motility. Each strain grewlogarithmically in the cornea up to 6 hours post-infection. SLE scores increasedfrom 0 to 30 hours post-infection for strains ATCC 14041 and 93-1399-1, whilethe SLE score of strain 94-EI-185-2 reached its maximum at 18 hours post-infection.Strain-specific differences in pathology were noted from 18 to 30 hours post-infection.Strain 94-EI-185-2 produced iritis but only mild corneal changes. Strain 93-1399-1produced a severe corneal infiltrate encompassing the entire corneal surfaceas well as severe conjunctival inflammation and iritis. Strain ATCC 14041produced a localized, severe, exudative corneal abscess that contained infectingbacteria. CONCLUSIONS. A rabbit model of Serratia keratitis was developedin which bacterial growth kinetics and strain-specific ocular pathologic changeswere reproducible. [ABSTRACT FROM AUTHOR]