title: Isolation of Anti-Ricin Protective Antibodies Exhibiting High Affinity from Immunized Non-Human Primates.
abstract: Ricin, derived from the castor bean plant Ricinus communis, is one of the most potent and lethal toxins known, against which there is no available antidote. To date, the use of neutralizing antibodies is the most promising post-exposure treatment for ricin intoxication. The aim of this study was to isolate high affinity anti-ricin antibodies that possess potent toxin-neutralization capabilities. Two non-human primates were immunized with either a ricin-holotoxin- or subunit-based vaccine, to ensure the elicitation of diverse high affinity antibodies. By using a comprehensive set of primers, immune scFv phage-displayed libraries were constructed and panned. A panel of 10 antibodies (five directed against the A subunit of ricin and five against the B subunit) was isolated and reformatted into a full-length chimeric IgG. All of these antibodies were found to neutralize ricin in vitro, and several conferred full protection to ricin-intoxicated mice when given six hours after exposure. Six antibodies were found to possess exceptionally high affinity toward the toxin, with KD values below pM (k(off )< 1 × 10(-7) s(-1)) that were well correlated with their ability to neutralize ricin. These antibodies, alone or in combination, could be used for the development of a highly-effective therapeutic preparation for post-exposure treatment of ricin intoxication.
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. taln@iibr.gov.il.
authors.forename: Tal
authors.initials: T
authors.lastname: Noy-Porat
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. ronitr@iibr.gov.il.
authors.forename: Ronit
authors.initials: R
authors.lastname: Rosenfeld
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. naomia@iibr.gov.il.
authors.forename: Naomi
authors.initials: N
authors.lastname: Ariel
authors.affiliation: Department of Biotechnology, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. eyale@iibr.gov.il.
authors.forename: Eyal
authors.initials: E
authors.lastname: Epstein
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. rona@iibr.gov.il.
authors.forename: Ron
authors.initials: R
authors.lastname: Alcalay
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. anatz@iibr.gov.il.
authors.forename: Anat
authors.initials: A
authors.lastname: Zvi
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. chanochk@iibr.gov.il.
authors.forename: Chanoch
authors.initials: C
authors.lastname: Kronman
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. arieo@iibr.gov.il.
authors.forename: Arie
authors.initials: A
authors.lastname: Ordentlich
authors.affiliation: Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona 76100, Israel. ohadm@iibr.gov.il.
authors.forename: Ohad
authors.initials: O
authors.lastname: Mazor
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology* / Q000494:pharmacology; D000939:Epitopes / Q000276:immunology; D005260:Female; D006027:Glycosides / Q000276:immunology; D006367:HeLa Cells; D006801:Humans; D007114:Immunization; D008253:Macaca mulatta; D008813:Mice, Inbred ICR; D012276:Ricin / Q000276:immunology* / Q000633:toxicity; D014315:Triterpenes / Q000276:immunology; D022223:Vaccines, Subunit / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D000939:Epitopes; D006027:Glycosides; D014315:Triterpenes; D022223:Vaccines, Subunit; C001883:stichoposide; D012276:Ricin
keywords: affinity; antibody; immunization; neutralization; non-human primates; ricin