Passive Immunization with mAbs Against Aerosolized Ricin Toxin

Ricin Toxin Structure Model

The Centers for Disease Control and Prevention (CDC) recognize that the deliberate release of biological toxins and highly infectious agents into the public sphere remains a threat to both military and civilian personnel. Ricin toxin is considered a high potential threat because of its accessibility, stability, and extreme toxicity, especially by inhalation.

The full cytotoxic and inflammatory potential of ricin toxin are especially apparent in the lung following aerosol exposure. Given rapid onset of toxicity, the opportunity to intervene and reverse the effects of lethal dose of ricin exposure is likely to be mere hours.

This study details pre-exposure infusion with a single monoclonal antibody (MAb) at a dose of 25 mg/kg as sufficient to protect non-human primates against a lethal dose ricin toxin aerosol challenge one month later. By all metrics, huPB10-LS prophylaxis afforded the same degree of immunity to Rhesus macaques as was achieved through active vaccination with RiVax, an RTA-based subunit vaccine. This raises the prospect that a single MAb-based drug product can afford both immediate and long-lasting (e.g., months) immunity to a notorious biothreat agent.

Authors affiliated with the following organizations contributed to this research: Vaccines and Therapeutics Division, Defense Threat Reduction Agency; Tulane National Primate Research Center; Wadsworth Center Division of Infectious Disease; Mapp Biopharaceutical; Walter Reed Institute of Research Clinical Pharmacology Branch; and University of Texas Southwestern Medical Center.

Roy, C.J., Van Slyke, G., Ehrbar, D. et al. Passive immunization with an extended half-life monoclonal antibody protects Rhesus macaques against aerosolized ricin toxinnpj Vaccines Published: 13 February 2020.

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