Progress in the Development of Vaccines Against Ricin Intoxication
Pp. 110-129 (20)
Virginia I. Roxas-Duncan and Leonard A. Smith
Ricin is a potent phytotoxin that presents a significant public health concern due
to its potential use as a bioterrorism agent. Exposure to ricin results in local tissue necrosis
and general organ failure leading to death within several days. Currently, there is no U.S.
FDA-approved drug or vaccine against ricin poisoning. Because vaccination offers a
practical prophylactic strategy to protect selected populations at risk of ricin exposure, there
has been a great deal of interest in developing a safe and effective vaccine to protect
humans, in particular soldiers and first responders. Generation of non-toxic derivatives of
ricin or ricin A chain (RTA) for use as vaccines has been initially attempted by several
groups using formalin treatment, chemical deglycosylation, or mutagenesis by substitution
or insertion. Most of these efforts resulted in unstable protein products that aggregated in
solution, had residual toxicity, or expressed poorly in recombinant form. At present, two
leading recombinant RTA vaccine candidates, RiVax (University of Texas) and RVEc
(USAMRIID), are in advanced development in clinical trials. This chapter reviews the
efforts, challenges, and progress toward the development of ricin vaccines.
Ricin, recombinant ricin vaccine, RVEc, RiVax, ricin toxoid, RTA,
Senior Research Scientist (ST) for Medical Countermeasures Technology, Office of Chief Scientist, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA.