Construction and biological characterization of Brucella S2Δbp26

Abstract:

Objective To develop a safe, effective, and identifiable new vaccine.Methods The gene deletion strain S2Δbp26 was constructed by homologous recombination with S2 as the parental strain. The stability, safety, and efficacy of S2Δbp26 were then evaluated.Results The phenotype and genotype of S2Δbp26 did not change after 20 successive passages in vitro. The experiments in mice and guinea pigs showed that there was no difference in biosafety between S2Δbp26 and S2. The bacterial load was less than 2×10⁵ CFU per gram of spleen in guinea pigs inoculated with S2Δbp26 at different passages and S2, which suggested that the virulence of the mutant strain was attenuated. The mice inoculated with S2ΔBP26 had a shorter 50% recovery time than those inoculated with S2. Meanwhile, the mice immunized with S2Δbp26 could successfully resist the challenge with M28 wild-type strain at a dose of 2×10⁵ CFU/mouse.Conclusion S2Δbp26 was successfully constructed, with excellent safety and immunoprotective capacity, which provided technical reserves for the development of identifiable vaccines for brucellosis.

Key words:Brucella;vaccine;S2Δbp26;biological characterization