Camelid VHHs Fused to Human Fc Fragments Provide Long Term Protection Against Botulinum Neurotoxin A in Mice

• Published in: Toxins Vol. 11; no. 8; p. 464
• Main Authors: Godakova, Svetlana A, Noskov, Anatoly N, Vinogradova, Irina D, Ugriumova, Galina A, Solovyev, Andrey I, Esmagambetov, Ilias B, Tukhvatulin, Amir I, Logunov, Denis Y, Naroditsky, Boris S, Shcheblyakov, Dmitry V, Gintsburg, Aleksandr L
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.08.2019; MDPI
• Subjects: Antibodies; Antigens; Antitoxins; Binding sites; Blood; Blood circulation; Botulinum toxin type A; Botulism; camelid single-domain antibodies; Cloning; Clostridium botulinum; Complementarity-determining region 3; dimers; Display devices; Fatalities; Fc fragments; Food contamination; Food contamination & poisoning; IgG antibody; Immunization; Immunoglobulin G; Intoxication; Lethal dose; Microorganisms; Nanobodies; Nervous system; Neurotoxins; Neutralizing; Phage display; Phages; toxin neutralization; Toxins; VHH; dimers; toxin neutralization; Clostridium botulinum; phage display; VHH; Fc fragments; camelid single-domain antibodies
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins11080464

The bacterium is the causative agent of botulism-a severe intoxication caused by botulinum neurotoxin (BoNT) and characterized by damage to the nervous system. In an effort to develop novel immunotherapeutics, camelid single-domain antibodies (sdAbs, VHHs, or nanobodies) could be used due to their unique structure and characteristics. In this study, VHHs were produced using phage display technology. A total of 15 different monoclonal VHHs were selected based on their comlementarity-determining region 3 (CDR3) sequences. Different toxin lethal dose (LD ) challenges with each selected phage clone were conducted in vivo to check their neutralizing potency. We demonstrated that modification of neutralizing VHHs with a human immunoglobulin G (IgG)1 Fc (fragment crystallizable) fragment (fusionbody, VHH-Fc) significantly increased the circulation time in the blood (up to 14 days). At the same time, VHH-Fc showed the protective activity 1000 times higher than monomeric form when challenged with 5 LD . Moreover, VHH-Fcs remained protective even 14 days after antibody administration. These results indicate that this VHH-Fc could be used as an effective long term antitoxin protection against botulinum type A.