Capsular polysaccharide of Streptococcus agalactiae is an essential virulence factor for infection in Nile tilapia (Oreochromis niloticus Linn.)
Capsular polysaccharide of Streptococcus agalactiae is an essential virulence factor for infection in Nile tilapia (Oreochromis niloticus Linn.)
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无乳链球菌荚膜多糖是尼罗罗非鱼 (Oreochromis niloticus Linn.) 感染的重要毒力因子。
DOI：
10.1111/jfd.12935
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发表时间：
2019
影响因子：
2.5
通讯作者：
Fengling Qin
中科院分区：
文献类型：
--
作者：
Defeng Zhang;Xiaoli Ke;Zhigang Liu;Jianmeng Cao;Youlu Su;Maixin Lu;Fengying Gao;Miao Wang;Mengmeng Yi;Fengling Qin
无乳链球菌(B群链球菌，GBS)与水产动物的多种疾病有关。由cps基因簇编码的荚膜多糖(CPS)是无乳链球菌的主要毒力因子，然而，关于Ia型鱼GBS菌株的CPS在鱼类中的致病作用尚不清楚。本研究通过对Δ基因簇进行插入突变，构建了一个非包膜突变体(Cps)。通过对罗非鱼全血的杀灭、体内感染、罗非鱼脾组织中突变株存活率的测定和病理分析，对突变株的体外致病性进行了评价。与野生型(WT)相比，Δcps突变体对新鲜罗非鱼全血的体外抗性较低(P<；0.01)，在罗非鱼脾组织中更容易清除，在罗非鱼和斑马鱼中高度减弱。此外，与Δcps突变株相比，WT株感染的罗非鱼脾组织中存在大量的GBS菌株和严重的组织坏死。这些结果表明，CPS在GBS的致病过程中是必不可少的，并可作为疫苗开发中减毒的靶标。更好地了解GBS在鱼类中的致病作用，将为深入了解相关的发病机制和宿主-病原体的相互作用提供依据。
Streptococcus agalactiae (Group B Streptococcus, GBS) is associated with diverse diseases.in aquatic animals. The capsule polysaccharide (CPS) encoded by the cps gene.cluster is the major virulence factor of S. agalactiae; however, limited information is.available regarding the pathogenic role of the CPS of serotype Ia piscine GBS strains.in fish. Here, a non‐encapsulated mutant (Δcps) was constructed by insertional mutagenesis.of the cps gene cluster. Mutant pathogenicity was evaluated in vitro based.on the killing of whole blood from tilapia, in vivo infections, measuring mutant survival.in tilapia spleen tissues and pathological analysis. Compared to wild‐type (WT).GBS strain, the Δcps mutant had lower resistance to fresh tilapia whole blood in vitro.(p < 0.01), and more easily cleared in tilapia spleen tissue, and was highly attenuated.in tilapia and zebrafish. Additionally, compared to the Δcps mutant, numerous GBS.strains and severe tissue necrosis were observed in the tilapia spleen tissue infected.with WT strains. These results indicated that the CPS is essential for GBS pathogenicity.and may serve as a target for attenuation in vaccine development. Gaining a.better understanding of the role, the GBS pathogenicity in fish will provide insight.into related pathogenesis and host–pathogen interactions.