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Cross-protection studies with Pasteurella multocida bacterins prepared from bacteria propagated in iron-depleted
J R Glisson1, M D Contreras, I H Cheng
1Department of Avian Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602.
Abstract:
Strains X-73 (serotype 1) and P-1059 (serotype 3) of Pasteurella multocida, avian origin, expressed additional membrane proteins (MPs) when grown in brain-heart infusion (BHI) broth containing the iron chelator dipyridyl and when grown in BHI broth treated with the iron chelator Chelex 100. These additional MPs were not detected when both strains were grown in BHI broth. Chickens and turkeys were vaccinated twice with inactivated oil-emulsion vaccines containing bacterial cells expressing these MPs or with vaccines containing bacterial cells grown in BHI broth. Two weeks after the final vaccination, all birds were challenged to determine whether bacterins made from P. multocida that had been propagated in conditions of iron deprivation would induce heterologous serotype immunity. The bacterins produced in medium low in iron did not consistently induce significant protection against heterologous challenge.
Insights
Iron-deprived Pasteurella multocida vaccines did not consistently protect chickens and turkeys against different serotypes. Further research is needed to improve avian Pasteurella multocida vaccine efficacy.
Area of Science:
- Veterinary microbiology
- Immunology
Background:
- Pasteurella multocida is a significant pathogen in avian species.
- Outer membrane proteins (MPs) are crucial for bacterial virulence and immune response.
- Iron availability influences bacterial gene expression and protein profiles.
Purpose of the Study:
- To investigate the immunogenicity of Pasteurella multocida grown under iron-restricted conditions.
- To evaluate the potential of iron-regulated MPs for inducing heterologous serotype immunity in poultry.
Main Methods:
- Two strains of Pasteurella multocida (serotypes 1 and 3) were cultured in iron-depleted media using chelators.
- Bacterial cells expressing unique MPs were used to create inactivated oil-emulsion vaccines.
- Chickens and turkeys were vaccinated twice and subsequently challenged with homologous and heterologous serotypes.
Main Results:
- Culturing Pasteurella multocida in iron-depleted broth induced the expression of additional membrane proteins.
- Vaccination with bacterins from iron-deprived cultures did not consistently provide significant protection against heterologous serotype challenge.
- The induced immunity was not reliably effective across different serotypes.
Conclusions:
- Bacterins derived from iron-regulated Pasteurella multocida outer membrane proteins do not consistently induce broad-spectrum heterologous serotype immunity in poultry.
- Current strategies of using iron-regulated proteins for vaccine development may require further optimization for effective cross-protection against avian Pasteurella multocida infections.