Li Gang, Niu Hui, Zhang Yanhe, Li Yanling, Xie Fang, Langford Paul R, Liu Siguo, Wang Chunlai
State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
Section of Paediatrics, Department of Medicine, Imperial College London, St. Mary's Campus, London, United Kingdom.
PLoS One. 2017 May 18;12(5):e0177199. doi: 10.1371/journal.pone.0177199. eCollection 2017.
Haemophilus parasuis is the causative agent of Glasser's disease in pigs. Cytolethal distending toxin (CDT) is an important virulence factor of H. parasuis. It is composed of three subunits: CdtA, CdtB and CdtC and all were successfully expressed in soluble form in Escherichia coli when the signal peptides were removed. Purified CdtB had DNase activity, i.e. caused DNA double strand damage, in vitro and in vivo prior to cell arrest and apoptosis. Flow cytometry analysis showed CdtB alone could induce cell cycle arrest and apoptosis in PK-15 porcine kidney and pulmonary alveolar macrophage (PAM) cells, which could be enhanced by CdtA or/and CdtC. CDT holotoxin could lead to significant cell distension, G2 arrest and apoptotic death in PK-15 and PAM cells. The apoptosis induced by CDT holotoxin was significantly inhibited by pifithrin-α, which indicates that it is p53-dependent. The results suggest that H. parasuis CDT holotoxin is a major virulence factor.
副猪嗜血杆菌是猪格氏病的病原体。细胞致死膨胀毒素（CDT）是副猪嗜血杆菌的一种重要毒力因子。它由三个亚基组成：CdtA、CdtB和CdtC，当去除信号肽后，所有这些亚基都能在大肠杆菌中以可溶形式成功表达。纯化的CdtB在体外和体内细胞停滞和凋亡之前具有DNA酶活性，即导致DNA双链损伤。流式细胞术分析表明，单独的CdtB可诱导PK - 15猪肾细胞和肺泡巨噬细胞（PAM）的细胞周期停滞和凋亡，CdtA或/和CdtC可增强这种作用。CDT全毒素可导致PK - 15和PAM细胞出现明显的细胞膨胀、G2期停滞和凋亡死亡。pifithrin - α可显著抑制CDT全毒素诱导的凋亡，这表明其依赖于p53。结果表明，副猪嗜血杆菌CDT全毒素是一种主要的毒力因子。
