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Protection against infection in mice vaccinated with a Brucella abortus mutant
M L Boschiroli1, S L Cravero, A I Arese
1Instituto de Biotecnologia, Centro de Investigacion en Ciencias Veterinarias, Moron, Provincia Buenos Aires, Argentina.
Abstract:
This study determines whether a genetically engineered mutant of Brucella abortus, strain M-1, possesses differences in protective properties compared to the parental strain, vaccine S19. M-1 is a mutant unable to express BP26, a periplasmic protein with potential use in diagnosis. Mice vaccinated with S19 developed antibodies against BP26, while those vaccinated with M-1 did not. However, mice vaccinated with S19 or M-1 were similarly protected against challenge with pathogenic strain 2308, suggesting that the lack of BP26 does not affect the induction of the protective immune response exerted by S19. These and previous results showing that bacterial invasion and growth or replication in mouse spleens were indistinguishable between strains M-1 and S19 could indicate that the mutant is an attenuated strain which maintains the same protective properties as S19.
Insights
A Brucella abortus mutant, M-1, lacking the BP26 protein, offers similar protection against infection as the S19 vaccine strain. This suggests BP26 is not essential for inducing a protective immune response in mice.
Area of Science:
- Veterinary immunology
- Bacterial pathogenesis
- Vaccine development
Background:
- Brucella abortus is a significant livestock pathogen.
- Vaccine strain S19 is widely used but can elicit confusing diagnostic results.
- The BP26 protein's role in Brucella virulence and immunity is not fully understood.
Purpose of the Study:
- To evaluate the protective efficacy of a Brucella abortus mutant (M-1) lacking BP26 expression.
- To compare the immunogenicity and protective properties of M-1 against the parental vaccine strain S19.
- To determine if BP26 is essential for the protective immune response induced by S19.
Main Methods:
- Generation of a Brucella abortus mutant (M-1) deficient in BP26 expression.
- Vaccination of mice with either M-1 or S19 strains.
- Serological analysis for antibody production against BP26.
- Challenge studies using a virulent Brucella abortus strain (2308).
- Assessment of bacterial load in spleen tissues.
Main Results:
- Mice vaccinated with S19 produced antibodies against BP26; M-1 vaccinated mice did not.
- Both S19 and M-1 vaccination conferred similar protection against challenge with virulent Brucella abortus 2308.
- Bacterial invasion and replication in the spleen were comparable between M-1 and S19 vaccinated groups.
- The absence of BP26 did not impair the induction of protective immunity.
Conclusions:
- Brucella abortus strain M-1, lacking BP26, retains the protective properties of vaccine strain S19.
- BP26 expression is not required for S19-mediated protection against Brucella abortus challenge.
- The M-1 mutant may represent an attenuated vaccine candidate with improved diagnostic potential.