MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.
PLoS Pathog. 2024 Sep 12;20(9):e1012513. doi: 10.1371/journal.ppat.1012513. eCollection 2024 Sep.
Porcine circovirus type 2 (PCV2) often causes disease through coinfection with other bacterial pathogens, including Glaesserella parasuis (G. parasuis), which causes high morbidity and mortality, but the role played by PCV2 and bacterial and host factors contributing to this process have not been defined. Bacterial attachment is assumed to occur via specific receptor-ligand interactions between adhesins on the bacterial cell and host proteins adsorbed to the implant surface. Mass spectrometry (MS) analysis of PCV2-infected swine tracheal epithelial cells (STEC) revealed that the expression of Extracellular matrix protein (ECM) Fibronectin (Fn) increased significantly on the infected cells surface. Importantly, efficient G. parasuis serotype 4 (GPS4) adherence to STECs was imparted by interactions with Fn. Furthermore, abrogation of adherence was gained by genetic knockout of Fn, Fn and Integrin β1 antibody blocking. Fn is frequently exploited as a receptor for bacterial pathogens. To explore the GPS4 adhesin that interacts with Fn, recombinant Fn N-terminal type I and type II domains were incubated with GPS4, and the interacting proteins were pulled down for MS analysis. Here, we show that rare lipoprotein A (RlpA) directly interacts with host Fibronectin mediating GPS4 adhesion. Finally, we found that PCV2-induced Fibronectin expression and adherence of GPS4 were prevented significantly by TGF-β signaling pathway inhibitor SB431542. Our data suggest the RlpA-Fn interaction to be a potentially promising novel therapeutic target to combat PCV2 and GPS4 coinfection.
猪圆环病毒 2 型（PCV2）常通过与其他细菌病原体（包括副猪嗜血杆菌（G. parasuis））共同感染而引起疾病，该病原体可导致高发病率和死亡率，但 PCV2 以及细菌和宿主因素在这一过程中所起的作用尚未确定。细菌附着被认为是通过细菌细胞上的黏附素与吸附在植入物表面的宿主蛋白之间的特定受体-配体相互作用发生的。对感染 PCV2 的猪气管上皮细胞（STEC）进行质谱（MS）分析显示，细胞表面外基质蛋白（ECM）纤维连接蛋白（Fn）的表达显著增加。重要的是，Fn 与 G. parasuis 血清型 4（GPS4）之间的相互作用赋予了 GPS4 对 STEC 的有效附着。此外，通过 Fn 的基因敲除、Fn 和整合素β1 抗体阻断，获得了附着的阻断。Fn 常被用作细菌病原体的受体。为了探索与 Fn 相互作用的 GPS4 黏附素，将重组 Fn N 端 I 型和 II 型结构域与 GPS4 孵育，并对相互作用的蛋白质进行 MS 分析。在这里，我们表明罕见脂蛋白 A（RlpA）直接与宿主纤维连接蛋白相互作用，介导 GPS4 黏附。最后，我们发现 TGF-β信号通路抑制剂 SB431542 显著阻止了 PCV2 诱导的纤维连接蛋白表达和 GPS4 的附着。我们的数据表明，RlpA-Fn 相互作用可能成为对抗 PCV2 和 GPS4 共同感染的有前途的新型治疗靶点。
