Protection from Streptococcus pneumoniae Keratitis by Passive Immunization with Pneumolysin Antiserum

Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
Investigative Ophthalmology &amp Visual Science (Impact Factor: 3.4). 01/2008; 49(1):290-4. DOI: 10.1167/iovs.07-0492
Source: PubMed


To determine whether passive immunization with pneumolysin antiserum can reduce corneal damage associated with pneumococcal keratitis.
New Zealand White rabbits were intrastromally injected with Streptococcus pneumoniae and then passively immunized with control serum, antiserum against heat-inactivated pneumolysin (HI-PLY), or antiserum against cytotoxin-negative pneumolysin (psiPLY). Slit lamp examinations (SLEs) were performed at 24, 36, and 48 hours after infection. An additional four corneas from rabbits passively immunized with antiserum against psiPLY were examined up to 14 days after infection. Colony forming units (CFUs) were quantitated from corneas extracted at 20 and 48 hours after infection. Histopathology of rabbit eyes was performed at 48 hours after infection.
SLE scores at 36 and 48 hours after infection were significantly lower in rabbits passively immunized with HI-PLY antiserum than in control rabbits (P < or = 0.043). SLE scores at 24, 36, and 48 hours after infection were significantly lower in rabbits passively immunized with psiPLY antiserum than in control rabbits (P < or = 0.010). The corneas of passively immunized rabbits that were examined up to 14 days after infection exhibited a sequential decrease in keratitis, with an SLE score average of 2.000 +/- 1.586 at 14 days. CFUs recovered from infected corneas were not significantly different between each experimental group and the respective control group at 20 or 48 hours after infection (P > or = 0.335). Histologic sections showed more corneal edema and polymorphonuclear leukocyte (PMN) infiltration in control rabbits compared with passively immunized rabbits.
HI-PLY and psiPLY both elicit antibodies that provide passive protection against S. pneumoniae keratitis.

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    • "Topical cholesterol was shown to signi�cantly reduce corneal in�ammation in pneumococcal keratitis, purportedly by acting as a competitor for host cholesterol and neutralizing pneumolysin [76] [77]. Another attempt at targeting pneumolysin was the use of active and passive immunization in an animal model of keratitis [73] [78]. Proteins other than pneumolysin have been shown to be important for virulence in nonocular pneumococcal diseases but have not been associated with keratitis to date. "
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    ABSTRACT: Ocular bacterial infections are universally treated with antibiotics, which can eliminate the organism but cannot reverse the damage caused by bacterial products already present. The three very common causes of bacterial keratitis-Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae-all produce proteins that directly or indirectly cause damage to the cornea that can result in reduced vision despite antibiotic treatment. Most, but not all, of these proteins are secreted toxins and enzymes that mediate host cell death, degradation of stromal collagen, cleavage of host cell surface molecules, or induction of a damaging inflammatory response. Studies of these bacterial pathogens have determined the proteins of interest that could be targets for future therapeutic options for decreasing corneal damage.
    Journal of Ophthalmology 01/2013; 2013(1):369094. DOI:10.1155/2013/369094 · 1.43 Impact Factor
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    • "In short, a 96-well ELISA plate was coated with mouse anti-PLY antibody (Affi nity BioReagents, Golden, CO, USA) and incubated overnight. The subsequent steps were blocking of nonspecific proteins, application of extracellular bacterial extracts, application of polyclonal rabbit PLY-specific antiserum (Green et al 2008), application of anti-rabbit IgG alkaline phosphatase conjugate (Sigma-Aldrich, St. Louis, MO, USA), and color development. The color intensity in each well was measured spectrophotometrically at A 405 . "
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    ABSTRACT: The purpose of this study was to determine whether the in vitro activity and concentration of Streptococcus pneumoniae pneumolysin correlated to the pathogenesis of S. pneumoniae endophthalmitis. Five S. pneumoniae clinical endophthalmitis strains were grown in media to similar optical densities (OD), and extracellular milieu was tested for pneumolysin activity by hemolysis of rabbit red blood cells. Pneumolysin concentration was determined using a sandwich ELISA. Rabbit vitreous was injected with 10(2) colony-forming units (CFU) of 1 of 2 different strains with low hemolytic activity (n = 10 and 12 for strains 4 and 5, respectively) or 1 of 3 different strains with high hemolytic activity (n = 12 per strain). Pathogenesis of endophthalmitis infection was graded by slit lamp examination (SLE) at 24 hours post-infection. Bacteria were recovered from infected vitreous and quantitated. The SLE scores of eyes infected with strains having high hemolytic activity were significantly higher than the scores of those infected with strains having low hemolytic activity (P < 0.05). Pneumolysin concentration in vitro, however, did not correlate with hemolysis or severity of endophthalmitis. Bacterial concentrations from the vitreous infected with 4 of the strains were not significantly different (P > 0.05). These data suggest that pneumolysin hemolytic activity in vitro directly correlates to the pathogenesis of S. pneumoniae endophthalmitis. The protein concentration of pneumolysin, however, is not a reliable indicator of pneumolysin activity.
    Clinical ophthalmology (Auckland, N.Z.) 01/2009; 2(4):793-800.
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    ABSTRACT: Streptococcus pneumoniae is a common cause of bacterial keratitis, and models to examine the ocular pathogenesis of this bacterium would aid in efforts to treat pneumococcal keratitis. The aim of this study was to establish a murine model of pneumococcal keratitis. The corneas of A/J, BALB/c or C57BL/6 mice were scratched and topically infected with a clinical strain of S. pneumoniae. Slitlamp examination (SLE), enumeration of bacteria in the corneas and histology were performed. Bacteria were recovered from the eyes of A/J mice on postinfection (PI) days 1 [1.96 +/- 0.61 log(10) colony-forming units (CFU)] and 3 (1.41 +/- 0.71 log(10) CFU). SLE scores were significantly higher in the infected A/J mice as compared to the BALB/c or C57BL/6 mice on PI day 3 (p < 0.0001) and steadily increased over time, reaching a maximal value of 3.00 +/- 0.35 on PI day 10. Histopathology revealed stromal edema and the influx of polymorphonuclear leukocytes on PI days 7 and 10, and corneal disruption on PI day 7. S. pneumoniae keratitis was established in A/J mice, but not BALB/c or C57BL/6 mice.
    Ophthalmic Research 08/2009; 42(3):141-6. DOI:10.1159/000229028 · 1.42 Impact Factor
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