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Brucella melitensis omp31 Mutant Is Attenuated and Confers Protection Against Virulent Brucella melitensis Challenge
L Verdiguel-Fernández1, R Oropeza-Navarro2, Adolfo Ortiz3
1Laboratorio de Microbiología Molecular, Departamento de Microbiología e Inmunología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, colonia UNAM CU, Coyoacán C.P 04510, CdMx, México.
Abstract:
For control of brucellosis in small ruminants, attenuated B. melitensis Rev1 is used but it can be virulent for animals and human. Based on these aspects, it is essential to identify potential immunogens to avoid these problems in prevention of brucellosis. The majority of OMPs in the Omp25/31 family have been studied because these proteins are relevant in maintaining the integrity of the outer membrane but their implication in the virulence of the different species of this genus is not clearly described. Therefore, in this work we studied the role of Omp31 on virulence by determining the residual virulence and detecting lesions in spleen and testis of mice inoculated with the B. melitensis LVM31 mutant strain. In addition, we evaluated the conferred protection in mice immunized with the mutant strain against the challenge with the B. melitensis Bm133 virulent strain. Our results showed that the mutation of omp31 caused a decrease in splenic colonization without generating apparent lesions or histopathological changes apparent in both organs in comparison with the control strains and that the mutant strain conferred similar protection as the B. melitensis Rev1 vaccine strain against the challenge with B. melitensis Bm133 virulent strain. These results allow us to conclude that Omp31 plays an important role on the virulence of B. melitensis in the murine model, and due to the attenuation shown by the strain, it could be considered a vaccine candidate for the prevention of goat brucellosis.
Insights
Brucellosis prevention in small ruminants needs safer alternatives to the Rev1 vaccine. Researchers found that mutating the Omp31 protein in Brucella melitensis reduced its virulence and showed potential as a vaccine candidate.
Area of Science:
- Veterinary Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- Brucellosis control in small ruminants relies on attenuated Brucella melitensis Rev1, which poses risks of residual virulence.
- Identifying novel immunogens is crucial for developing safer and more effective brucellosis prevention strategies.
- Outer membrane proteins (OMPs) like Omp31 are vital for bacterial integrity, but their role in Brucella virulence is not fully understood.
Purpose of the Study:
- To investigate the role of Omp31 in the virulence of Brucella melitensis.
- To evaluate a B. melitensis mutant strain lacking Omp31 as a potential vaccine candidate for brucellosis prevention.
Main Methods:
- Generation of a B. melitensis LVM31 mutant strain with omp31 deleted.
- Assessment of residual virulence, including splenic colonization and lesion development in mice.
- Evaluation of protective efficacy of the mutant strain against challenge with virulent B. melitensis Bm133.
Main Results:
- The omp31 mutant strain exhibited reduced splenic colonization in mice without causing significant lesions.
- Mice immunized with the omp31 mutant strain showed protection comparable to the Rev1 vaccine against virulent B. melitensis challenge.
- The mutant strain demonstrated significant attenuation in the murine model.
Conclusions:
- Omp31 is a key virulence factor in Brucella melitensis.
- The omp31-deficient B. melitensis strain shows promise as a safe and effective vaccine candidate for preventing brucellosis in goats.
