单克隆抗体S2C4对2型志贺毒素及其亚型毒性的中和作用

纯化的2型志贺毒素(Shiga toxin 2，Stx2)经福尔马林脱毒后免疫BALB/c小鼠制备Stx2单克隆抗体，用体外中和试验对具有中和活性的阳性抗体克隆进行初筛，对所获得的中和抗体的重、轻链同种型及结合特异性进行鉴定，其中和保护作用通过体内、体外中和试验加以验证，最后，中和抗体对Stx2亚型Stx2c和Stx2vha的中和谱用体内中和试验验证．结果显示，12株抗Stx2的阳性抗体克隆中，只有1株具有中和活性，命名为S2C4，其重、轻链同种型为G₁/κ，其靶分子为Stx2的A亚单位，与Stx2的B亚单位或Stx1不结合．在体外中和试验中S2C4可有效中和Stx2对Vero细胞的杀伤作用，同样，S2C4可中和致死量的Stx2及其亚型Stx2c和Stx2vha对小鼠的毒性作用．该抗体有望成为治疗产志贺毒素大肠杆菌感染的候选分子．

Monoclonal antibody S2C4 neutralizes the toxicity of shiga toxin 2 and its variants

Shiga toxin 2 (Stx2) toxoid produced by formaldehyde treatment of purified toxin was used to immunize BALB/c mice for monoclonal antibody (MAb) production.The neutralizing activities of positive clones against Stx2 were screened by in vitro cytotoxicity assay.The isotype and specificity of resultant clone was determined,and its efficacy to neutralize the activity of purified Stx2 was evaluated by in vitro and in vivo toxicity model.Lastly,its spectrum of activity against Stx2 variants was also accessed by mouse toxicity model.It was demonstrated that one of the 12 positive MAb clones against Stx2,designating $2C4 had neutralizing activity.S2C4 belongs to the immunoglobulin G1 subclass and has a K light chain,and it reacts with the A subunit of Stx2 and does not bind to Stx2 B subunit or to Stx1.S2CA could efficiently neutralize the cytotoxicity of Stx2 to Veto cells and mice.It also protected mice against lethal doses of Stx2 variants challenge including Stx2c and Stx2vha.S2C4 is a promising candidate molecule in preventing the progression of hemolytic-uremic syndrome (HUS) mediated mainly by Stx2 in Stx-producing Escherichia coli(STEC)infection.