Zhu Siping, Sun Xinyi, Li Hong, Su Yongmei, Li Chihuan, Zhu Xintong, Ren Chao, Liu Xiaochen, Dong Yulai, Shi Qiumei, Zhang Zhiqiang
Hebei Key Laboratory of Preventive Veterinary Medicine, Hebei Normal University of Science & Technology, Qinhuangdao, China.
College of Computer Engineering, Zhanjiang University of Science and Technology, Zhanjiang, China.
Front Microbiol. 2025 Aug 21;16:1626276. doi: 10.3389/fmicb.2025.1626276. eCollection 2025.
has the ability to adapt to variable environments by modulating metabolism. The Tricarboxylic Acid Cycle (TCA), as a core metabolic process, is critical for the environmental adaptation and infection process of . Fumarate reductase FrdA is an important enzyme in the TCA cycle, mainly catalyzing the conversion of fumarate to succinate. But the association between this enzyme and the pathogenicity of has not yet been reported.
To determine the role of fumarate reductase FrdA in infection, a -gene deletion strain of () was generated in this study, and the effect of knockout on the biological properties and pathogenicity of . were further examined. Then, the immunoprotective effect of -deficient strain was determined.
The results showed that deletion did not affect the growth properties of but caused a significant decreased survival under environmental stress, as well as a substantial decrease in its motility and biofilm formation ability. The Δ mutant displayed apparently reduced adhesion and invasion to Caco-2 cells and markedly impaired survival and replication in RAW264.7 cells. The animal infection test showed that the gene deletion could lead to a significant decrease in virulence of in mice, with a 64-fold increased LD for mice, and Δ demonstrated significantly decreased colonization in mouse tissues and organs. The transcriptomics results showed that deletion resulted in altered expression of 2163 genes in , and downregulated expression of and other virulence genes were confimed by qPCR. Moreover, immunization of mice with the deletion strain provided promising immune protection for mice.
Fumarate reductase FrdA is closely associated with pathogenicity of and that is an attractive candidate target for vaccine design of .
具有通过调节新陈代谢来适应多变环境的能力。三羧酸循环（TCA）作为核心代谢过程，对于其环境适应和感染过程至关重要。延胡索酸还原酶FrdA是TCA循环中的一种重要酶，主要催化延胡索酸向琥珀酸的转化。但该酶与致病性之间的关联尚未见报道。
为确定延胡索酸还原酶FrdA在感染中的作用，本研究构建了基因缺失菌株（），并进一步检测基因敲除对其生物学特性和致病性的影响。然后，确定基因缺陷菌株的免疫保护作用。
结果显示，基因缺失不影响其生长特性，但在环境压力下其存活率显著降低，运动性和生物膜形成能力也大幅下降。Δ突变体对Caco-2细胞的黏附与侵袭能力明显降低，在RAW264.7细胞中的存活与复制能力显著受损。动物感染试验表明，基因缺失可导致其对小鼠的毒力显著下降，小鼠的半数致死剂量（LD）增加64倍，且Δ在小鼠组织和器官中的定殖显著减少。转录组学结果显示，基因缺失导致中2163个基因的表达发生改变，定量PCR证实了和其他毒力基因的表达下调。此外，用基因缺失菌株免疫小鼠可为小鼠提供有前景的免疫保护。
延胡索酸还原酶FrdA与致病性密切相关，是疫苗设计的一个有吸引力的候选靶点。
