Botulinum Neurotoxins and Botulism: A Novel Therapeutic Approach

Toxins

Jeeraphong Thanongsaksrikul¹ 

[1] Laboratory for Research and Technology Development, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkok-noi, Bangkok 10700, Thailand;

关键词: botulinum neurotoxin;    botulism;    zinc metalloprotease;    immunotherapy;    serum therapy;    therapeutic antibody;    chimeric antibody;    humanized antibody;    single chain antibody variable fragment (ScFv);    heavy chain antibody (HCAb);    single domain antibody (sdAb);    VH;    VL;    V_HH;    humanized-camel phage display library;    nanobody;    transbody;    cell penetrating peptide (CPP);    phage display;   

DOI  :  10.3390/toxins3050469

来源: mdpi

【 摘 要 】

Specific treatment is not available for human botulism. Current remedial mainstay is the passive administration of polyclonal antibody to botulinum neurotoxin (BoNT) derived from heterologous species (immunized animal or mouse hybridoma) together with supportive and symptomatic management. The antibody works extracellularly, probably by blocking the binding of receptor binding (R) domain to the neuronal receptors; thus inhibiting cellular entry of the holo-BoNT. The antibody cannot neutralize the intracellular toxin. Moreover, a conventional antibody with relatively large molecular size (150 kDa) is not accessible to the enzymatic groove and, thus, cannot directly inhibit the BoNT zinc metalloprotease activity. Recently, a 15–20 kDa single domain antibody (V_HH) that binds specifically to light chain of BoNT serotype A was produced from a humanized-camel VH/V_HH phage display library. The V_HH has high sequence homology (>80%) to the human VH and could block the enzymatic activity of the BoNT. Molecular docking revealed not only the interface binding between the V_HH and the toxin but also an insertion of the V_HH CDR3 into the toxin enzymatic pocket. It is envisaged that, by molecular linking the V_HH to a cell penetrating peptide (CPP), the CPP-V_HH fusion protein would be able to traverse the hydrophobic cell membrane into the cytoplasm and inhibit the intracellular BoNT. This presents a novel and safe immunotherapeutic strategy for botulism by using a cell penetrating, humanized-single domain antibody that inhibits the BoNT by means of a direct blockade of the groove of the menace enzyme.

【 授权许可】

CC BY   
© 2011 by the authors; licensee MDPI, Basel, Switzerland.