United States Army Medical Research Institute of Chemical Defense
The Center for Catalytic Bioscavenger Medical Defense Research

Leaders in Translational Research

The consortium based at USAMRICD, under the direction of Center PI Dr. David Lenz, has been established to exploit the expertise of scientific leaders in the areas of biochemistry, molecular biology and protein expression systems. The research projects are aligned within three synergistic paths which while scientifically independent, interact to provide the overall direction needed to produce viable products.
Bioscavengers Development Schematic Path 1Path 2Path 3Project 1Project 2Project 3Project 4Project 5Project 6Expression CandidatesTesting CoreCandidates for Advanced Development
Path 1

Building on the success of the stoichiometric BioScavenger human butyrylcholinesterase (HuBuChE), the next generation of protein drugs being developed is based on both HuBuChE and human Paraoxonase 1(PON 1).
Project One
Employs rational design based upon homology modeling studies and site directed mutations of specific amino acid residues of PON 1 which in its wild type form has been shown to catalyze the hydrolysis of a variety of nerve agents such as GD, GB and VX.
Project Two
Focuses upon re-engineering HuBuChE. Combining cutting edge molecular biology techniques, rationally directed mutagenesis, error-prone PCR, and gene shuffling, to generate a diversified huBuChE mutation library which is screened for variants that are both resistant to OP inhibition and that hydrolyze OP analogues.
Project Three
Applies directed evolution via gene shuffling techniques to generate mutant libraries of PON 1, which is screened using a proprietary throughput assay system selecting for enhanced OP catalytic activity, the technology has been shown to be successful in concept and has been adapted for the next generation of human PON mutants.
Path 2

The data generated in Path 2 provide elucidation of the chemical processes underlying in the catalytic mechanism of action of the enzymes of interest and drive Path One efforts to design human wild-type protein mutations capable of enhancing catalytic activity against nerve agents.
Project Four
Focuses on the elucidation of the mechanism of hydrolysis of nerve agents by serine or non-serine active-site-containing human proteins via physio-chemical studies of chemical agents, and spectroscopic characterization of binding domains and catalytic processes, protein structure and in silico modeling, QSAR, and X-ray crystallography.

The data generated drive Path One efforts to design human wild-type protein mutations capable of enhancing catalytic activity against nerve agents.
Path 3

To provide a reliable, safe, non supply-limited and inexpensive source of Bioscavenger enzymes, plant protein expression platforms are being adapted to produce recombinant pharmaceutical grade proteins. The expression teams receive constructs of promising human protein drug candidates after in vitro testing core validation and optimize the expression systems to express the codon-optimized human enzyme gene product.

To further refine the expression systems, and reduce human antigenicity properties inherent to plant produced proteins, plant gyclosation patterns are being characterized and adapted to mimic human glyco-forms to extend the protein drug half-life in circulation and reduce side effects.
Project Five
Genetically engineers tobacco plants to express the protein mutant candidates.
Project Six
Uses cell wall-less strains of Chlamydomonas micro-algae as a platform to produce mutant human protein candidates.

Testing Core Efficacy Feedback

Core B – Completes testing of promising catalytic Bioscavengers of which the results will inform the decision points critical to further development of the candidate compounds. The plant produced proteins are tested to evaluate properties and provide feedback of the plant expression systems. The testing protocol includes in vitro characterization of enzymatic activity against live nerve agents (NA) as well as preliminary in vivo screening for efficacy and or safety in small animal models pursuant to preparation of IND submissions to the FDA.