Intranasal vaccination of rabbits with Pasteurella multocida A:3 outer membranes that express iron-regulated proteins.
OBJECTIVE
To determine efficacy of intranasal vaccination of rabbits with Pasteurella multocida A:3 outer membrane proteins (OMP) expressing iron-regulated OMP (IROMP) in conferring protection against experimental challenge exposure.


METHODS
52 male New Zealand White rabbits.


METHODS
Rabbits were vaccinated intranasally on days 0, 7, and 14; some vaccines included cholera toxin (CT) as an adjuvant. Concentrations of intranasal IgA and serum IgG antibodies against P multocida OMP were determined. In experiment A, rabbits were vaccinated with either phospate-buffered saline solution (PBSS), PBSS-CT, OMP-CT, or IROMP-CT, challenge-exposed intranasally on day 16, and euthanatized and necropsied on day 28. Rabbits were also vaccinated with OMP or IROMP without CT and were not challenge-exposed. In experiment B, rabbits were vaccinated with PBSS, PBSS-CT, IROMP, or IROMP-CT. On day 17, rabbits were challenge-exposed intranasally. Nasal bacteria and antibodies were determined on day 24.


RESULTS
In experiment A, OMP-CT vaccination stimulated mucosal and systemic antibody responses to the bacterium and enhanced resistance against challenge exposure. Intranasal bacterial counts were not significantly reduced. Vaccination with IROMP-CT stimulated mucosal and systemic antibodies, enhanced resistance to challenge exposure, and significantly reduced nasal bacterial counts. In experiment B, natural infection was detected in several rabbits at challenge exposure; however, IROMP-CT-vaccinated rabbits had significantly higher serum and nasal antibody responses, compared with other rabbits IROMP-CT-vaccinated rabbits had significantly lower nasal bacterial counts compared to control rabbits.


CONCLUSIONS
Intranasal vaccination of rabbits with P multocida outer membranes containing IROMP and CT stimulated immunity against experimental pneumonic pasteurellosis.
Confer
A W
AW
Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078, USA.
Suckow
M A
MA
Montelongo
M
M
Dabo
S M
SM
Miloscio
L J
LJ
Gillespie
A J
AJ
Meredith
G L
GL
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000281:Administration, Intranasal; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology* / Q000592:standards; D002772:Cholera Toxin / Q000008:administration & dosage; D004797:Enzyme-Linked Immunosorbent Assay; D007501:Iron / Q000502:physiology; D033862:Iron-Binding Proteins; D008297:Male; D009296:Nasal Cavity / Q000382:microbiology; D010326:Pasteurella Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D016979:Pasteurella multocida / Q000254:growth & development / Q000276:immunology*; D033902:Periplasmic Binding Proteins; D011817:Rabbits / Q000276:immunology*; D014611:Vaccination / Q000662:veterinary*
D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D033862:Iron-Binding Proteins; D033902:Periplasmic Binding Proteins; D002772:Cholera Toxin; D007501:Iron