Protective effect of two recombinant ricin subunit vaccines in the New Zealand white rabbit subjected to a lethal aerosolized ricin challenge: survival, immunological response, and histopathological findings.

Ricin, isolated from the castor bean plant Ricinus communis, is included on the Centers for Disease Control and Prevention Category B list of bioterrorism agents, indicating that the toxin is moderately easy to disseminate and could result in moderate morbidity rates. This study evaluated two promising recombinant ricin subunit vaccines, one made using an Escherichia coli codon-optimized gene and the other using a yeast codon-optimized gene in E. coli-based fermentations.

Progress in biological threat agent vaccine development: a repeat-dose toxicity study of a recombinant ricin toxin A-chain (rRTA) 1-33/44-198 vaccine (RVEc) in male and female New Zealand white rabbits.

A recombinant ricin toxin A-chain 1-33/44-198 vaccine (RVEc) was administered to male and female New Zealand white (NZW) rabbits (10/sex/group) in a repeat-dose toxicity study. The RVEc vaccine was administered on study days 1, 29, 57, and 85 via intramuscular (IM) injection (0, 100, or 200 μg/dose). All study animals were observed throughout treatment until euthanized and submitted for necropsy on study day 88 or 99 (recovery period).