Humanization and Characterization of an Anti-Ricin Neutralization Monoclonal Antibody

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Authors
  1. Hu, W-G.
  2. Yin, J.
  3. Chau, D.
  4. Negrych, L.M.
  5. Cherwonogrodzky, J.W.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN)
Abstract
Ricin is regarded as a high terrorist risk for the public due to its high toxicity and ease of production. Currently, there is no therapeutic or vaccine available against ricin. D9, a murine monoclonal antibody developed previously in our laboratory, can strongly neutralize ricin and is therefore a good candidate for humanization. Humanization of D9 variable regions was achieved by a complementarity-determining region grafting approach. The humanized D9 (hD9) variable regions were further grafted onto human heavy and light chain constant regions to assemble the complete antibody gene. A foot-and-mouth-disease virus-derived 2A self-processing sequence was introduced between heavy and light chain DNA sequences to cleave the recombinant protein into a functional full-length antibody molecule from a single open reading frame driven by a single promoter in an adenoviral vector. After expression in mammalian cells and purification, the hD9 was demonstrated to have equimolar expression of the full-length antibody heavy and light chains. More importantly, the hD9 exhibited high affinity to ricin with KD of 1.63 nM, comparable to its parental murine D9 (2.55 nM). In a mouse model, intraperitoneal (i.p.) administration of hD9, at a low dose of 5 μg per mouse, 4 hours after the i.p. challenge with 5×LD50 ricin was found to rescue 100% of the mice. In addition, administered 6 hours post-challenge, hD9 could still rescue 50% of the mice. The hD9 has the potential to be used for prop
Report Number
DRDC-SUFFIELD-SL-2012-061 — Scientific Letter
Date of publication
08 Feb 2017
Number of Pages
26
DSTKIM No
CA044645
CANDIS No
804969
Format(s):
Electronic Document(PDF)

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