Li Shiyu, Li Wei, Liang Qiancai, Cao Jizhen, Li Han, Li Zhicheng, Li Anxing
State Key Laboratory of Biocontrol/Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals and Institute of Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
Innovative Institute of Animal Healthy Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China.
Front Microbiol. 2023 Apr 17;14:1121621. doi: 10.3389/fmicb.2023.1121621. eCollection 2023.
There are a variety of regulatory systems in bacteria, among which the two-component system (TCS) can sense external environmental changes and make a series of physiological and biochemical reactions, which is crucial for the life activities of bacteria. As a member of TCS, is considered to be an important virulence factor in s, but its function in tilapia ()-derived remains unknown. To explore the role of in regulating virulence in the two-component system (TCS) of from tilapia, Δ mutant strain and CΔ complementary strain were constructed by homologous recombination. The results showed that the abilities of growth and biofilm formation of Δ strain were significantly decreased when cultured in a brain heart infusion (BHI) medium ( < 0.01). Also, the survival rate of the Δ strain in blood was decreased when compared with the wild strain THN0901. Under the higher infection dose, the accumulative mortality of tilapia caused by the Δ strain was significantly decreased (23.3%), of which THN0901 and CΔ strains were 73.3%. The results of competition experiments in tilapia showed that the invasion and colonization abilities of the Δ strain were also dramatically lower than those of the wild strain ( < 0.01). Compared with the THN0901, the mRNA expression levels of virulence factors (, , , , etc.) in the Δ strain were significantly down-regulated ( < 0.01). is one of the virulence factors of . It plays a role in promoting host colonization and achieving immune evasion during the infection of tilapia, which provides a basis for exploring the pathogenic mechanism of infected with tilapia.
细菌中有多种调控系统，其中双组分系统（TCS）能够感知外部环境变化并引发一系列生理生化反应，这对细菌的生命活动至关重要。作为TCS的一员，被认为是[细菌名称]中的一种重要毒力因子，但其在罗非鱼源[细菌名称]中的功能仍不清楚。为了探究[具体基因名称]在罗非鱼源[细菌名称]的双组分系统（TCS）中调控毒力的作用，通过同源重组构建了Δ突变株和CΔ互补株。结果表明，当在脑心浸液（BHI）培养基中培养时，Δ菌株的生长和生物膜形成能力显著下降（P<0.01）。此外，与野生菌株THN0901相比，Δ菌株在血液中的存活率降低。在较高感染剂量下，由Δ菌株引起的罗非鱼累积死亡率显著降低（23.3%），其中THN0901和CΔ菌株为73.3%。罗非鱼体内竞争实验结果表明，Δ菌株的侵袭和定殖能力也显著低于野生菌株（P<0.01）。与THN0901相比，Δ菌株中毒力因子（[毒力因子名称列举]等）的mRNA表达水平显著下调（P<0.01）。[具体基因名称]是[细菌名称]的毒力因子之一。它在罗非鱼感染过程中促进宿主定殖和实现免疫逃逸方面发挥作用，这为探究罗非鱼感染[细菌名称]的致病机制提供了依据。
