title: Human monoclonal antibodies generated following vaccination with AVA provide neutralization by blocking furin cleavage but not by preventing oligomerization.
abstract: In order to identify the combination of antibody-mediated mechanisms of neutralization that result from vaccination with anthrax vaccine adsorbed (AVA), we isolated antibody secreting cells from a single donor seven days after booster vaccination with AVA and generated nine fully human monoclonal antibodies (hmAb) with high specificity for protective antigen (PA). Two of the antibodies were able to neutralize lethal toxin in vitro at low concentrations (IC(50): p6C01, 0.12 μg/ml and p6F01, 0.45 μg/ml). Passive transfer of either of these hmAbs to A/J mice prior to challenge with lethal toxin conferred 80-90% protection. We demonstrate that hmAb p6C01 is neutralizing by preventing furin cleavage of PA in a dose-dependent manner, but the mechanism of p6F01 is unclear. Three additional antibodies were found to bind to domain 3 of PA and prevent oligomerization, although they did not confer significant protection in vivo and showed a significant prozone-like effect in vitro. These fully human antibodies provide insight into the neutralizing response to AVA for future subunit vaccine and passive immunotherapeutic cocktail design.
authors.affiliation: Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Smith
authors.forename: Sherry R
authors.initials: SR
authors.lastname: Crowe
authors.forename: Lori
authors.initials: L
authors.lastname: Garman
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Guthridge
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Muther
authors.forename: Emily
authors.initials: E
authors.lastname: McKee
authors.forename: Nai-Ying
authors.initials: NY
authors.lastname: Zheng
authors.forename: A Darise
authors.initials: AD
authors.lastname: Farris
authors.forename: Joel M
authors.initials: JM
authors.lastname: Guthridge
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Wilson
authors.forename: Judith A
authors.initials: JA
authors.lastname: James
mesh_terms: D000818:Animals; D000881:Anthrax / Q000517:prevention & control*; D022122:Anthrax Vaccines / Q000276:immunology*; D000907:Antibodies, Bacterial / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D057134:Antibodies, Neutralizing / Q000276:immunology*; D000942:Antigens, Bacterial / Q000378:metabolism*; D000992:Antitoxins / Q000276:immunology*; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D045683:Furin / Q000037:antagonists & inhibitors*; D006801:Humans; D007116:Immunization, Passive; D020128:Inhibitory Concentration 50; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008875:Middle Aged; D009500:Neutralization Tests; D055503:Protein Multimerization; D059748:Proteolysis
chemical_list: D022122:Anthrax Vaccines; D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000942:Antigens, Bacterial; D000992:Antitoxins; D001427:Bacterial Toxins; C030325:anthrax toxin; D045683:Furin