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M.E. Marquart, K.S. Monds, A.R. Caballero, L.S. McDaniel, R.J. O'Callaghan; Passive Immunization of Rabbits With Pneumolysin Antiserum to Treat Streptococcus Pneumoniae Keratitis . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1078.
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© ARVO (1962-2015); The Authors (2016-present)
Test polyclonal antiserum, raised against the toxin pneumolysin, for the passive treatment of pneumococcal keratitis.
Rabbit anti–pneumolysin polyclonal antiserum was produced by immunizing each of 3 New Zealand white rabbits subcutaneously with a 1:1 mixture of complete Freund’s adjuvant and 0.1 mg recombinant pneumolysin, and then boosting with a 1:1 mixture of incomplete Freund’s adjuvant and 0.05 mg recombinant pneumolysin 3 weeks later. Control serum was generated by injecting rabbits with a 1:1 mixture of Freund’s and PBS. The serum from the rabbit producing the highest ELISA titer of pneumolysin antiserum was chosen for passive immunization. Six new rabbits were injected intrastromally with 100,000 colony–forming units (CFU) of S. pneumoniae strain WU2. Three of these rabbits were given 1 ml of pneumolysin antiserum intravenously immediately following infection, whereas the remaining 3 were given 1 ml of control serum. Slit lamp examinations (SLE) of eyes were done at 24, 36, and 48 hours post–infection. Rabbits were sacrificed following the last SLE and corneal CFU were determined by dilution plating of corneal homogenates.
The anti–pneumolysin serum used for passive immunization produced an ELISA titer of approximately 50,000, and the control serum had a background titer of 200. SLE scores of passively immunized rabbits (n = 6 corneas) were significantly lower than the control rabbits (n = 5 corneas) at 36 hours post–infection (6.833 ± 0.528 vs. 10.350 ± 0.490, respectively; P = 0.001) and 48 hours post–infection (7.417 ± 1.233 vs. 13.050 ± 1.220, respectively; P = 0.011). The most striking difference observed was the amount of infiltrate in the corneal stroma. Log CFU at 48 hours post–infection were not significantly different between passively immunized (2.617 ± 1.136) and control (2.124 ± 0.798) rabbit corneas (P = 0.742).
Passive immunization with pneumolysin antiserum significantly reduced the symptoms of S. pneumoniae keratitis.
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