Brucella melitensis M5-90Δbp26 as a potential live vaccine that allows for the distinction between natural infection...

Area of Science:

• Veterinary microbiology
• Bacterial pathogenesis
• Vaccine development

Background:

• Brucella is a Gram-negative intracellular bacterium causing significant economic losses globally.
• Live attenuated Brucella vaccines like Brucella melitensis M5-90 are effective but have limitations.
• Current vaccines hinder distinguishing between natural infection and immunization and can cause abortions.

Purpose of the Study:

• To construct and evaluate the virulence and immunogenicity of a Brucella M5-90Δbp26 mutant.
• To assess the safety of the M5-90Δbp26 mutant compared to the parent vaccine strain.
• To develop a method for differentiating vaccinated animals from infected ones.

Main Methods:

• Construction of the Brucella M5-90Δbp26 mutant.
• In vitro survival assays in human placenta trophoblastic 8 cells (HPT-8 cells).
• In vivo virulence and immunoprotection studies in BALB/c mice.
• Safety evaluation of the mutant compared to the M5-90 strain.
• Development and validation of an indirect enzyme-linked immunosorbent assay (ELISA) for Brucella protein 26 (BP26) detection.

Main Results:

• The M5-90Δbp26 mutant exhibited attenuated survival in HPT-8 cells and BALB/c mice.
• The mutant demonstrated high immunoprotective efficacy in mice.
• Safety tests confirmed the M5-90Δbp26 mutant is less virulent than the M5-90 vaccine.
• An indirect ELISA successfully detected BP26 with high sensitivity.
• M5-90Δbp26 inoculation resulted in a lack of BP26 expression, confirmed by western blotting.

Conclusions:

• The Brucella M5-90Δbp26 mutant is a promising candidate for a safer and more effective brucellosis vaccine.
• The combination of the M5-90Δbp26 mutant and indirect ELISA allows for accurate differentiation between vaccinated and infected animals.
• This approach can significantly improve brucellosis surveillance and control strategies in livestock.