title: Genetic and immunological comparison of anti-botulinum type A antibodies from immune and non-immune human phage libraries.
abstract: Understanding the antibody response in botulinum intoxication is important for vaccine design and passive prophylaxis. To investigate this activity, we have studied the immune response to BoNT/A (botulinum neurotoxin serotype A) binding domain (HC) at the molecular level using phage display. The scFv antibodies were isolated from V-gene repertoires prepared from (a) human volunteer immunized with pentavalent botulinum toxoid and (b) non-immune human peripheral blood lymphocytes and spleenocytes. A large panel of serotype specific phage expressing botulinum binding scFv could be selected from both libraries. Epitope mapping of immune scFv binders towards BoNT/A HC revealed surprisingly a limited number of scFv recognizing conformational epitopes that corresponded to two distinct groups, clusters I and II. Only scFv from cluster I exhibited neutralizing activity in the mouse hemidiaphragm assay. Anti- BoNT/A HC clones derived from a non-immune library could be conveniently grouped into clusters III-XI and appeared to share no overlapping epitopes with cluster I or II. In addition they showed no neutralization of toxin at biologically significant concentrations. We therefore suggest that a vaccine based on the pentavalent botulinum toxoid directs the humoral immune response to a limited number of immunodominant epitopes exposed on the binding domain HC.
authors.affiliation: Department of Anesthesia and Pharmaceutical Chemistry, San Francisco General Hospital, University of California, San Francisco Rm 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA. peter_amersdorfer@corvas.com
authors.forename: Peter
authors.initials: P
authors.lastname: Amersdorfer
authors.forename: Cindy
authors.initials: C
authors.lastname: Wong
authors.forename: Theresa
authors.initials: T
authors.lastname: Smith
authors.forename: Steven
authors.initials: S
authors.lastname: Chen
authors.forename: Sharad
authors.initials: S
authors.lastname: Deshpande
authors.forename: Robert
authors.initials: R
authors.lastname: Sheridan
authors.forename: James D
authors.initials: JD
authors.lastname: Marks
mesh_terms: D000907:Antibodies, Bacterial / Q000235:genetics* / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology; D019274:Botulinum Toxins, Type A / Q000276:immunology* / Q000633:toxicity; D001906:Botulism / Q000276:immunology / Q000517:prevention & control / Q000628:therapy; D003014:Clostridium botulinum / Q000276:immunology; D018604:Epitope Mapping; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D009500:Neutralization Tests; D019151:Peptide Library
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D007135:Immunoglobulin Variable Region; D019151:Peptide Library; D019274:Botulinum Toxins, Type A