Randy L. Jones

Biochemical and aerosol characterization of ricin for use in non-clinical efficacy studies

Ricin toxin may be used as a biological warfare agent and no medical countermeasures are currently available. Here, a well‐characterized lot of ricin was aerosolized to determine the delivered dose for future pre‐clinical efficacy studies. Mouse intraperitoneal (IP) median lethal dose (LD50) bioassay measured potency at 5.62 and 7.35 μg/kg on Days 0 and 365, respectively. Additional analyses included total protein, sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, and rabbit reticulocyte lysate activity assay. The nebulizer aerosol produced consistent concentrations (2.5 × 103, 5.0 × 103, 1.0 × 104, and 1.5 × 104 μg/mL) and spray factor values. The aerosol particle size distribution was of sufficient size to deposit in lung alveoli (1.12–1.43 μm). Ricinus communis Agglutinin II (RCA 60), prepared at 19 mg/mL in phosphate‐buffered saline, pH 7.8, and stored at −70°C, maintained attributes for toxicity following 1‐year storage and aerosolized consistently.