title: Assessing the stoichiometric efficacy of mammalian expressed paraoxonase-1 variant I-F11 to afford protection against G-type nerve agents.
abstract: We evaluated the ability of evolved paraoxonase-1 (PON1) to afford broad spectrum protection against G-type nerve agents when produced in mammalian cells via an adenovirus expression system. The PON1 variants G3C9, VII-D11, I-F11, VII-D2 and II-G1 were screened in vitro for their ability to hydrolyze G-agents, as well as for their preference towards hydrolysis of the more toxic P(-) isomer. I-F11, with catalytic efficiencies of (1.1 ± 0.1) × 106M-1min-1, (2.5 ± 0.1) × 106M-1min-1, (2.3 ± 0.5) × 107M-1min-1and (9.2 ± 0.1) × 106M-1min-1against tabun (GA), sarin (GB), soman (GD) and cyclosarin (GF), respectively, was found to be a leading candidate for further evaluation. To demonstrate the broad spectrum efficacy of I-F11 against G-agents, a sequential 5 × LD50dose of GD, GF, GB and GA was administered to ten mice expressing I-F11 on days 3, 4, 5 and 6 following virus injection, respectively. At the conclusion of the experiment, 80% of the animals survived exposure to all four G-agents. Using the concept of stoichiometric efficacy, we determined that I-F11 affords protection from lethality against an administered dose of 10, 15, 90 and 80 molar equivalents of GA, GB, GD and GF, respectively, relative to the molar equivalents of I-F11 in circulation. It also appears that I-F11 can associate with high density lipoprotein in circulation, suggesting that I-F11 retained this function of native PON1. This combination of attractive attributes demonstrates that I-F11 is an attractive candidate for development as a broad-therapeutic against G-type nerve agent exposure.
authors.affiliation: Physiology & Immunology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Mata
authors.affiliation: Physiology & Immunology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, USA.
authors.forename: Praveena
authors.initials: P
authors.lastname: Sabnekar
authors.affiliation: Physiology & Immunology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, USA.
authors.forename: Cetara A
authors.initials: CA
authors.lastname: Watson
authors.affiliation: Physiology & Immunology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, USA.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Rezk
authors.affiliation: Physiology & Immunology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, USA. Electronic address: Nageswararao.chilukuri.civ@mail.mil.
authors.forename: Nageswararao
authors.initials: N
authors.lastname: Chilukuri
mesh_terms: D000256:Adenoviridae / Q000378:metabolism; D000818:Animals; D043303:Aryldialkylphosphatase / Q000378:metabolism*; D055162:Biocatalysis / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D006868:Hydrolysis; D008075:Lipoproteins, HDL / Q000378:metabolism; D008297:Male; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism*; D000067397:Nerve Agents / Q000633:toxicity*; D000066829:Neuroprotection / Q000187:drug effects*; D015202:Protein Engineering
chemical_list: D008075:Lipoproteins, HDL; D050505:Mutant Proteins; D000067397:Nerve Agents; D043303:Aryldialkylphosphatase
keywords: Adenovirus-mediated gene delivery system; Catalytic bioscavengers; Chemical warfare nerve agents; Engineered paraoxonase-1 variants; High density lipoprotein-association