Deletion of pyrE disrupts pyrimidine de novo synthesis, attenuates virulence, and confers protective immunity as a live attenuated vaccine candidate against Brucella melitensis
Abstract
IntroductionBrucellosis, caused by Brucella spp., is a major zoonotic disease threatening public health and livestock production. Current live attenuated vaccines suffer from residual virulence and interference with serodiagnosis. Targeting essential metabolic pathways to generate auxotrophic mutants is a promising strategy for developing safer vaccines. The de novo pyrimidine synthesis pathway is critical for bacterial survival in nutrient-restricted intracellular environments. pyrE encodes orotate phosphoribosyltransferase, the key enzyme catalyzing the first committed step of pyrimidine synthesis. However, the role of this pathway in Brucella pathogenicity remains largely unexplored.MethodsA pyrE deletion mutant (ΔpyrE) and its complemented strain were constructed in B. melitensis M5. Growth characteristics, stress susceptibility, adhesion, invasion, intracellular survival, and BCV trafficking were assessed in vitro. Virulence, immunogenicity, and protective efficacy were evaluated in a mouse model with M5-90Δ26 as reference.ResultsΔpyrE exhibited uracil-dependent growth defects and impaired adhesion, invasion, and intracellular survival, but retained normal stress resistance and BCV trafficking to escape lysosomal degradation. In mice, ΔpyrE was significantly attenuated, with reduced splenic colonization and hepatic pathology. Immunization with ΔpyrE induced a durable Th1-biased immune response (elevated IgG2a and IFN-γ) and conferred protection comparable to M5-90Δ26, with superior long-term efficacy.ConclusionThis study demonstrates that pyrE is essential for pyrimidine synthesis and virulence in Brucella. The ΔpyrE strain represents a safe, immunogenic, and protective vaccine candidate with long-term potential, providing a new strategy for brucellosis control.
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BibTeX
@article{yang2026deletion,
title = {{Deletion of pyrE disrupts pyrimidine de novo synthesis, attenuates virulence, and confers protective immunity as a live attenuated vaccine candidate against Brucella melitensis}},
author = {Guangyu Yang and Simin Chen and Mengsi Li and Jing Qu and Xinmei Yang and Shaohui Wang and Yanqing Bao and Jingjing Qi and Lei Deng and Jiangang Hu and Mingxing Tian},
journal = {Frontiers in Immunology},
year = {2026},
month = nov,
doi = {10.3389/fimmu.2026.1935350},
url = {https://www.frontiersin.org/articles/10.3389/fimmu.2026.1935350},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Deletion of pyrE disrupts pyrimidine de novo synthesis, attenuates virulence, and confers protective immunity as a live attenuated vaccine candidate against Brucella melitensis
AU - Guangyu Yang
AU - Simin Chen
AU - Mengsi Li
AU - Jing Qu
AU - Xinmei Yang
AU - Shaohui Wang
AU - Yanqing Bao
AU - Jingjing Qi
AU - Lei Deng
AU - Jiangang Hu
AU - Mingxing Tian
PY - 2026
DA - 2026/11/06
JO - Frontiers in Immunology
DO - 10.3389/fimmu.2026.1935350
UR - https://www.frontiersin.org/articles/10.3389/fimmu.2026.1935350
AB - IntroductionBrucellosis, caused by Brucella spp., is a major zoonotic disease threatening public health and livestock production. Current live attenuated vaccines suffer from residual virulence and interference with serodiagnosis. Targeting essential metabolic pathways to generate auxotrophic mutants is a promising strategy for developing safer vaccines. The de novo pyrimidine synthesis pathway is critical for bacterial survival in nutrient-restricted intracellular environments. pyrE encodes orotate phosphoribosyltransferase, the key enzyme catalyzing the first committed step of pyrimidine synthesis. However, the role of this pathway in Brucella pathogenicity remains largely unexplored.MethodsA pyrE deletion mutant (ΔpyrE) and its complemented strain were constructed in B. melitensis M5. Growth characteristics, stress susceptibility, adhesion, invasion, intracellular survival, and BCV trafficking were assessed in vitro. Virulence, immunogenicity, and protective efficacy were evaluated in a mouse model with M5-90Δ26 as reference.ResultsΔpyrE exhibited uracil-dependent growth defects and impaired adhesion, invasion, and intracellular survival, but retained normal stress resistance and BCV trafficking to escape lysosomal degradation. In mice, ΔpyrE was significantly attenuated, with reduced splenic colonization and hepatic pathology. Immunization with ΔpyrE induced a durable Th1-biased immune response (elevated IgG2a and IFN-γ) and conferred protection comparable to M5-90Δ26, with superior long-term efficacy.ConclusionThis study demonstrates that pyrE is essential for pyrimidine synthesis and virulence in Brucella. The ΔpyrE strain represents a safe, immunogenic, and protective vaccine candidate with long-term potential, providing a new strategy for brucellosis control.
SN - 1664-3224
ER -