Investigation of Evolved Paraoxonase-1 Variants for Prevention of Organophosphorous Pesticide Compound Intoxication

Abstract

We investigated the ability of the engineered paraoxonase-1 variants G3C9, VII-D11, I-F11 and VII-D2 to afford protection against paraoxon intoxication. Paraoxon is the toxic metabolite of parathion, a common pesticide still in use in many developing countries. An in vitro investigation showed that VII-D11 is the most efficient variant at hydrolyzing paraoxon for the enzyme expressed via adenovirus infection of 293A cells and mice, respectively. Compared to the G3C9 parent scaffold, VII-D11 is 15-20 fold more efficacious at hydrolyzing paraoxon. Coinciding with these results, mice expressing VII-D11 in their blood survived and showed no symptoms against a cumulative 6.3 LD50 dose of paraoxon while mice expressing G3C9 experienced tremors and only 50% survival. We then determined whether VII-D11 can offer protection against paraoxon when present at substoichiometric concentrations. Mice containing varying concentrations of VII-D11 in their blood (0.2 - 4.1 mg/mL) were challenged with doses of paraoxon at fixed stoichiometric ratios that constitute up to a ten-fold molar excess of paraoxon to enzyme (1.4 - 27 LD(sub50) doses) and were assessed for tremors and mortality. Mice were afforded complete asymptomatic protection below a paraoxon to enzyme ratio of 8:1, whereas higher ratios produced tremors and/or mortality. VIID11 in mouse blood co-eluted with high density lipoprotein, suggesting an association between the two entities. Collectively, these results demonstrate that VII-D11 is a promising candidate for development as a prophylactic catalytic bioscavenger against organophosphorous pesticide toxicity.

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Document Details

Document Type
Technical Report
Publication Date
Apr 04, 2014
Accession Number
ADA617744

Entities

People

  • David G. Mata
  • Douglas M. Cerasoli
  • Nageswararao Chilukuri
  • Peter E. Rezk
  • Praveena Sabnekar

Organizations

  • United States Army Medical Research Institute of Chemical Defense

Tags

Communities of Interest

  • Biomedical

DTIC Thesaurus Topics

  • Acetylcholinesterases
  • Amino Acids
  • Biomedical Research
  • Chemical Synthesis
  • Chemical Warfare
  • Chemistry
  • Culture Techniques
  • G Agents
  • Gene Therapy
  • Infection
  • Intoxication
  • Medical Personnel
  • Molecular Weight
  • Nerve Agents
  • Pesticides
  • Pharmacology
  • Therapy

Readers

  • Mathematics or Statistics
  • Neurotoxicology
  • Underwater engineering and Marine Technology.