Protection from Streptococcus pneumoniae keratitis by passive immunization with pneumolysin antiserum.
OBJECTIVE
To determine whether passive immunization with pneumolysin antiserum can reduce corneal damage associated with pneumococcal keratitis.


METHODS
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.


RESULTS
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.


CONCLUSIONS
HI-PLY and psiPLY both elicit antibodies that provide passive protection against S. pneumoniae keratitis.
Green
Sherrina N
SN
Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
Sanders
Melissa
M
Moore
Quincy C
QC
Norcross
Erin W
EW
Monds
Kathryn S
KS
Caballero
Armando R
AR
McDaniel
Larry S
LS
Robinson
Sherrina A
SA
Onwubiko
Chinwendu
C
O'Callaghan
Richard J
RJ
Marquart
Mary E
ME
D000818:Animals; D000907:Antibodies, Bacterial / Q000008:administration & dosage*; D001426:Bacterial Proteins / Q000276:immunology; D015169:Colony Count, Microbial; D003315:Cornea / Q000382:microbiology; D003320:Corneal Ulcer / Q000382:microbiology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D015818:Eye Infections, Bacterial / Q000382:microbiology / Q000517:prevention & control*; D007116:Immunization, Passive; D011008:Pneumococcal Infections / Q000382:microbiology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011817:Rabbits; D013296:Streptococcus pneumoniae / Q000276:immunology; D013301:Streptolysins / Q000276:immunology*; D014611:Vaccination
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D022242:Pneumococcal Vaccines; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae