Protection of Rabbits Against Colonization and Morbidity Associated With Toxigenic Pasteurella multocida by...

Area of Science:

• Veterinary Microbiology
• Immunology

Background:

• Pasteurella multocida causes significant disease in rabbits.
• Heat-labile toxin (PMT) is a key virulence factor.
• Previous studies show PMT immunization confers protection, but its effect on colonization is unknown.

Purpose of the Study:

• To investigate the impact of PMT immunization on P. multocida colonization in rabbits.
• To evaluate the role of PMT as a colonization factor.

Main Methods:

• Rabbits were immunized with phosphate-buffered saline (PBS), cholera toxin (CT), inactivated PMT (IPMT), or IPMT + CT.
• P. multocida colonization was assessed by culturing CFUs from lungs and nasal lavage fluid.
• Immune responses (serum IgG, nasal IgA) against PMT were measured.

Main Results:

• IPMT immunization induced anti-PMT IgG and IgA responses, enhanced by CT.
• Significantly higher P. multocida CFUs were found in the lungs of IPMT-immunized rabbits compared to controls.
• IPMT immunization protected against lung inflammation (pleuritis and pneumonia).

Conclusions:

• PMT may function as a colonization factor in the rabbit lung.
• While immunization against PMT did not reduce colonization, it conferred protection against severe lung disease.