title: Prolonged prophylactic protection from botulism with a single adenovirus treatment promoting serum expression of a VHH-based antitoxin protein.
abstract: Current therapies for most acute toxin exposures are limited to administration of polyclonal antitoxin serum. We have shown that VHH-based neutralizing agents (VNAs) consisting of two or more linked, toxin-neutralizing heavy-chain-only VH domains (VHHs), each binding distinct epitopes, can potently protect animals from lethality in several intoxication models including Botulinum neurotoxin serotype A1 (BoNT/A1). Appending a 14 amino acid albumin binding peptide (ABP) to an anti-BoNT/A1 heterodimeric VNA (H7/B5) substantially improved serum stability and resulted in an effective VNA serum half-life of 1 to 2 days. A recombinant, replication-incompetent, adenoviral vector (Ad/VNA-BoNTA) was engineered that induces secretion of biologically active VNA, H7/B5/ABP (VNA-BoNTA), from transduced cells. Mice administered a single dose of Ad/VNA-BoNTA, or a different Ad/VNA, via different administration routes led to a wide range of VNA serum levels measured four days later; generally intravenous > intraperitoneal > intramuscular > subcutaneous. Ad/VNA-BoNTA treated mice were 100% protected from 10 LD50 of BoNT/A1 for more than six weeks and protection positively correlated with serum levels of VNA-BoNTA exceeding about 5 ng/ml. Some mice developed antibodies that inhibited VNA binding to target but these mice displayed no evidence of kidney damage due to deposition of immune complexes. Mice were also successfully protected from 10 LD50 BoNT/A1 when Ad/VNA-BoNTA was administered up to 1.5 hours post-intoxication, demonstrating rapid appearance of the protective VNA in serum following treatment. Genetic delivery of VNAs promises to be an effective method of providing prophylactic protection and/or acute treatments for many toxin-mediated diseases.
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: Jean
authors.initials: J
authors.lastname: Mukherjee
authors.affiliation: Department of Radiation Oncology, Washington University, St. Louis, Missouri, United States of America.
authors.forename: Igor
authors.initials: I
authors.lastname: Dmitriev
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: Michelle
authors.initials: M
authors.lastname: Debatis
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Tremblay
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: Gillian
authors.initials: G
authors.lastname: Beamer
authors.affiliation: Department of Radiation Oncology, Washington University, St. Louis, Missouri, United States of America.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Kashentseva
authors.affiliation: Department of Radiation Oncology, Washington University, St. Louis, Missouri, United States of America.
authors.forename: David T
authors.initials: DT
authors.lastname: Curiel
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Shoemaker
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood*; D001904:Botulinum Antitoxin / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D001906:Botulism / Q000097:blood / Q000276:immunology / Q000517:prevention & control*; D000229:Dependovirus / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D005822:Genetic Vectors / Q000008:administration & dosage; D051379:Mice; D014611:Vaccination
chemical_list: D057134:Antibodies, Neutralizing; D001904:Botulinum Antitoxin