Chen Zhaochun, Moayeri Mahtab, Zhou Yi-Hua, Leppla Stephen, Emerson Suzanne, Sebrell Andrew, Yu Fujuan, Svitel Juraj, Schuck Peter, St Claire Marisa, Purcell Robert
Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Infect Dis. 2006 Mar 1;193(5):625-33. doi: 10.1086/500148. Epub 2006 Feb 2.
Four single-chain variable fragments (scFvs) against protective antigen (PA) and 2 scFvs against lethal factor (LF) of anthrax were isolated from a phage display library generated from immunized chimpanzees. Only 2 scFvs recognizing PA (W1 and W2) neutralized the cytotoxicity of lethal toxin in a macrophage lysis assay. Full-length immunoglobulin G (IgG) of W1 and W2 efficiently protected rats from anthrax toxin challenge. The epitope recognized by W1 and W2 was conformational and was formed by C-terminal amino acids 614-735 of PA. W1 and W2 each bound to PA with an equilibrium dissociation constant of 4x10-11 mol/L to 5x10(-11) mol/L, which is an affinity that is 20-100-fold higher than that for the interaction of the receptor and PA. W1 and W2 inhibited the binding of PA to the receptor, suggesting that this was the mechanism of protection. These data suggest that W1 and W2 chimpanzee monoclonal antibodies may serve as PA entry inhibitors for use in the emergency prophylaxis against and treatment of anthrax.
从免疫黑猩猩构建的噬菌体展示文库中分离出4种针对炭疽保护性抗原(PA)的单链可变片段(scFv)和2种针对炭疽致死因子(LF)的scFv。在巨噬细胞裂解试验中,只有2种识别PA的scFv(W1和W2)中和了致死毒素的细胞毒性。W1和W2的全长免疫球蛋白G(IgG)有效地保护大鼠免受炭疽毒素攻击。W1和W2识别的表位是构象性的,由PA的C末端氨基酸614 - 735形成。W1和W2与PA结合的平衡解离常数为4×10⁻¹¹ mol/L至5×10⁻¹¹ mol/L,该亲和力比受体与PA相互作用的亲和力高20 - 100倍。W1和W2抑制PA与受体的结合,表明这是其保护机制。这些数据表明,W1和W2黑猩猩单克隆抗体可作为PA进入抑制剂,用于炭疽的紧急预防和治疗。