Nagendra Suryanarayana, Verma Sarika, Tuteja Urmil, Thavachelvam Kulanthaivel
Division of Microbiology, Defence Research and Development Establishment, Gwalior, Madhya Pradesh 474002, India.
Toxicon. 2015 Dec 15;108:108-14. doi: 10.1016/j.toxicon.2015.10.004. Epub 2015 Oct 21.
Bacillus anthracis lethal toxin (LeTx) is the principle factor responsible for toxaemia and anthrax related death. Lethal toxin consist of two proteins viz protective antigen (PA) and lethal factor which combines in a typical fashion similar to other toxins belonging to A-B toxin super family. The amount of LeTx required to kill a particular organism generally differs among strains owing to their geographical distributions and genetic variation. In the present study, we have cloned PA and LF genes from B. anthracis clinical isolate of Indian origin and expressed them in soluble form employing Escherichia coli expression system. Both the proteins were purified to near homogeneity level using Immobilized metal ion affinity chromatography (IMAC). Further we have used equal ratio of both the proteins to form LeTx and determined its acute toxicity level in Balb/c mice by graphical method of Miller and Tainter. The LD50 value of LeTx by intravenous (i.v) route was found to be 0.97 ± 0.634 mg kg(-1) Balb/c mice. This study highlights the expression of recombinant LeTx from E. coli and assessing its acute toxicity level in experimental mouse model.
炭疽杆菌致死毒素（LeTx）是导致毒血症和炭疽相关死亡的主要因素。致死毒素由两种蛋白质组成，即保护性抗原（PA）和致死因子，它们以一种典型的方式结合，类似于其他属于A - B毒素超家族的毒素。由于不同菌株的地理分布和基因变异，杀死特定生物体所需的LeTx量通常有所不同。在本研究中，我们从印度来源的炭疽杆菌临床分离株中克隆了PA和LF基因，并利用大肠杆菌表达系统以可溶形式表达它们。使用固定化金属离子亲和色谱（IMAC）将这两种蛋白质纯化至接近均一水平。此外，我们使用等比例的这两种蛋白质形成LeTx，并通过米勒和泰纳特的图解法测定其在Balb/c小鼠中的急性毒性水平。经静脉（i.v.）途径，LeTx对Balb/c小鼠的LD50值为0.97±0.634 mg kg(-1)。本研究着重于从大肠杆菌中表达重组LeTx并在实验小鼠模型中评估其急性毒性水平。
