Protective immunization in mice against group B streptococci using encapsulated C5a peptidase.
OBJECTIVE
The purpose of the study was to test whether C5a peptidase encapsulated within a biodegradable polymer can act as a vaccine and elicit an immune response to prevent group B streptococci (GBS) infection in mice and provide protection to pups.


METHODS
C5a peptidase was encapsulated in semipermeable microspheres of poly(lactide-co-glycolide). Female ICR mice were immunized with encapsulated C5a peptidase, free C5a peptidase, or empty microparticles. Booster doses were given at days 21 and 42. Antibody responses were measured by enzyme-linked immunosorbent assay. Challenge with GBS type III was performed 4 days after the final booster in the vaginal vault of adult mice and intraperitoneally 48 hours after the birth for pups.


RESULTS
Encapsulated C5a peptidase elicited a systemic immunoglobulin (Ig) G antibody response after intramuscular and intranasal administration. Unencapsulated C5a peptidase elicited a smaller systemic response. In addition to the strong IgG response, a secretory IgA response was observed in the vaginal mucosa after intranasal vaccination. No evidence of GBS colonization was found in vaccinated mice. Eighty-seven percent and 81% of the pups from intramuscularly and intranasally vaccinated dams survived a 90% lethal dose (LD90) GBS challenge vs 9% born to nonvaccinated dams.


CONCLUSIONS
Encapsulated C5a peptidase elicited significant immune responses and protection against GBS challenge. C5a peptidase microsphere encapsulation has potential as a GBS vaccine.
Santillan
Donna A
DA
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Andracki
Mark E
ME
Hunter
Stephen K
SK
D018829:Adhesins, Bacterial / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D010450:Endopeptidases / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018928:Immunity, Mucosal; D007114:Immunization / Q000379:methods*; D051379:Mice; D008813:Mice, Inbred ICR; D008863:Microspheres; D011247:Pregnancy; D011270:Pregnancy, Animal; D011336:Probability; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000276:immunology / Q000517:prevention & control*; D022541:Streptococcal Vaccines / Q000494:pharmacology; D013292:Streptococcus agalactiae / Q000276:immunology*
D018829:Adhesins, Bacterial; D022541:Streptococcal Vaccines; D010450:Endopeptidases; C053088:C5a peptidase