Streptococcus agalactiae is a common pathogen in aquatic animals, especially tilapia, that hinders aquaculture development and leads to serious economic losses. Previously, a S. agalactiae strain named HN016 was identified from infected tilapia, and the attenuated strain YM001 was subsequently obtained by continuous passaging in Tryptic Soy Broth (TSB) medium. YM001 has been demonstrated as a safe vaccine for S. agalactiae infection in tilapia. To understand the molecular bases of the virulence of these two strains, we performed proteomic and transcriptomic analysis to reveal the protein and gene expression changes in the liver and intestine during the infection process. HN016 significantly decreased the contents of white blood cells (WBCs), neutrophils (NEUs), red blood cells (RBCs) and hematocrit (HCT) and increased the levels of total protein (TP), albumin (ALB) and globulin (GLO), while no such significant differences were observed when comparing the control with YM001. During the infection process, pathogenic peptidoglycan hydrolase, CSPA and membrane proteins were significantly differentially expressed between YM001 and HN016. Furthermore, both proteome and transcriptome data showed that the complement and coagulation cascades pathway and the antigen processing and presentation pathway were stimulated in the liver and intestine, respectively, by YM001 infection compared to HN016 infection. The interaction network analysis of key virulence genes from pathogens suggested that CSPA, as a key node, affects the expression of DOLPP1, MIPEP, PA2G4, OCIAD1, G3BP1 and CLIC5 with a positive correlation. The present evidence suggests that during the infection process, CSPA was the key genes contributing to low virulence in YM001.

中文翻译：

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尼罗罗非鱼（Oreochromis niloticus）中蛋白质组和双重转录组的大规模分析，其中无乳链球菌的低毒力和高毒力。

无乳链球菌是水生动物，特别是罗非鱼中常见的病原体，它阻碍了水产养殖的发展并导致严重的经济损失。以前，从受感染的罗非鱼中鉴定出一种名为HN016的无乳链球菌菌株，随后通过在胰蛋白酶大豆肉汤（TSB）培养基中连续传代获得减毒菌株YM001。YM001已被证明是用于罗非鱼无乳链球菌感染的安全疫苗。为了了解这两种菌株的毒力的分子基础，我们进行了蛋白质组和转录组分析，以揭示感染过程中肝脏和肠道中蛋白质和基因表达的变化。HN016显着降低了白细胞（WBCs），中性粒细胞（NEUs），红细胞（RBCs）和血细胞比容（HCT）并增加了总蛋白（TP），白蛋白（ALB）和球蛋白（GLO）的水平，但与YM001进行比较时未观察到这种显着差异。在感染过程中，致病性肽聚糖水解酶，CSPA和膜蛋白在YM001和HN016之间显着差异表达。此外，蛋白质组和转录组数据均显示，与HN016感染相比，YM001感染分别在肝和肠中刺激了补体和凝血级联途径以及抗原加工和呈递途径。来自病原体的关键毒力基因的相互作用网络分析表明，CSPA作为关键节点，对DOLPP1，MIPEP，PA2G4，OCIAD1，G3BP1和CLIC5的表达具有正相关。