title: Post-exposure treatment of VX poisoned guinea pigs with the engineered phosphotriesterase mutant C23: a proof-of-concept study.
abstract: The highly toxic organophosphorus (OP) nerve agent VX is characterized by a remarkable biological persistence which limits the effectiveness of standard treatment with atropine and oximes. Existing OP hydrolyzing enzymes show low activity against VX and hydrolyze preferentially the less toxic P(+)-VX enantiomer. Recently, a phosphotriesterase (PTE) mutant, C23, was engineered towards the hydrolysis of the toxic P(-) isomers of VX and other V-type agents with relatively high in vitro catalytic efficiency (kcat/KM=5×10(6)M(-1)min(-1)). To investigate the suitability of the PTE mutant C23 as a catalytic scavenger, an in vivo guinea pig model was established to determine the efficacy of post-exposure treatment with C23 alone against VX intoxication. Injection of C23 (5mgkg(-1) i.v.) 5min after s.c. challenge with VX (∼2LD50) prevented systemic toxicity. A lower C23 dose (2mgkg(-1)) reduced systemic toxicity and prevented mortality. Delayed treatment (i.e., 15min post VX) with 5mgkg(-1) C23 resulted in survival of all animals and only in moderate systemic toxicity. Although C23 did not prevent inhibition of erythrocyte acetylcholinesterase (AChE) activity, it partially preserved brain AChE activity. C23 therapy resulted in a rapid decrease of racemic VX blood concentration which was mainly due to the rate of degradation of the toxic P(-)-VX enantiomer that correlates with the C23 blood levels and its kcat/KM value. Although performed under anesthesia, this proof-of-concept study demonstrated for the first time the ability of a catalytic bioscavenger to prevent systemic VX toxicity when given alone as a single post-exposure treatment, and enables an initial assessment of a time window for this approach. In conclusion, the PTE mutant C23 may be considered as a promising starting point for the development of highly effective catalytic bioscavengers for post-exposure treatment of V-agents intoxication.
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany. Electronic address: franzworek@bundeswehr.org.
authors.forename: Franz
authors.initials: F
authors.lastname: Worek
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Seeger
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Reiter
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Goldsmith
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Yacov
authors.initials: Y
authors.lastname: Ashani
authors.affiliation: Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel; Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Haim
authors.initials: H
authors.lastname: Leader
authors.affiliation: Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Joel L
authors.initials: JL
authors.lastname: Sussman
authors.affiliation: Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Aggarwal
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
authors.forename: Horst
authors.initials: H
authors.lastname: Thiermann
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Dan S
authors.initials: DS
authors.lastname: Tawfik
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood; D000818:Animals; D000931:Antidotes / Q000008:administration & dosage* / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D002384:Catalysis; D002619:Chemical Warfare Agents / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity*; D002800:Cholinesterase Inhibitors / Q000097:blood / Q000493:pharmacokinetics / Q000633:toxicity*; D004334:Drug Administration Schedule; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology; D006168:Guinea Pigs; D006868:Hydrolysis; D008297:Male; D009154:Mutation; D020258:Neurotoxicity Syndromes / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology / Q000209:etiology; D009946:Organothiophosphorus Compounds / Q000097:blood / Q000493:pharmacokinetics / Q000633:toxicity*; D044345:Phosphoric Triester Hydrolases / Q000008:administration & dosage* / Q000235:genetics / Q000378:metabolism; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000008:administration & dosage; D013997:Time Factors
chemical_list: D000110:Acetylcholinesterase; D000931:Antidotes; D002619:Chemical Warfare Agents; D002800:Cholinesterase Inhibitors; D009946:Organothiophosphorus Compounds; D044345:Phosphoric Triester Hydrolases; D011994:Recombinant Proteins; C009680:VX-agent
keywords: Bioscavenger; Mutant; Nerve agents; Phosphotriesterase; Therapy; VX