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Updated: Jul 8, 2026
08:47
Opsonophagocytic Killing Assay to Assess Immunological Responses Against Bacterial Pathogens
Published on: April 5, 2019
Protection from Streptococcus pneumoniae keratitis by passive immunization with pneumolysin antiserum
Sherrina N Green1, Melissa Sanders, Quincy C Moore
1Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
Investigative Ophthalmology & Visual Science
|January 4, 2008
Summary
Passive immunization with antibodies against pneumolysin (HI-PLY and psiPLY) significantly reduced corneal damage in rabbits with pneumococcal keratitis, demonstrating protective effects against bacterial infection.
Area of Science:
- Ophthalmology
- Microbiology
- Immunology
Background:
- Streptococcus pneumoniae is a common cause of bacterial keratitis.
- Pneumolysin is a key virulence factor in S. pneumoniae infections.
- Corneal damage in bacterial keratitis can lead to vision loss.
Purpose of the Study:
- To evaluate the efficacy of passive immunization with pneumolysin antiserum in reducing corneal damage caused by S. pneumoniae.
Main Methods:
- New Zealand White rabbits were infected with S. pneumoniae.
- Rabbits received passive immunization with control serum, antiserum against heat-inactivated pneumolysin (HI-PLY), or antiserum against cytotoxin-negative pneumolysin (psiPLY).
- Corneal damage was assessed using slit lamp examinations (SLEs), colony forming units (CFUs), and histopathology.
Main Results:
- Passive immunization with both HI-PLY and psiPLY antisera significantly reduced SLE scores at multiple time points compared to controls.
- Histopathology revealed less corneal edema and polymorphonuclear leukocyte (PMN) infiltration in passively immunized rabbits.
- Bacterial load (CFUs) did not differ significantly between groups, suggesting a mechanism independent of bacterial clearance.
Conclusions:
- Antibodies targeting pneumolysin (HI-PLY and psiPLY) provide passive protection against Streptococcus pneumoniae keratitis.
- Passive immunization is a potential therapeutic strategy for bacterial keratitis.
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