This study is a Phase 1, escalating, multiple-dose, single-center study to evaluate the
safety and immunogenicity of the RVEc vaccine.
The two principal hypotheses to be tested are: RVEc vaccine will display an acceptable safety
profile as determined by adverse event data and RVEc vaccine will elicit ELISA immunoglobulin
G (IgG) titers greater than or equal to 1:500 and toxin-neutralizing antibody (TNA)
anti-ricin toxin-neutralizing antibody titers greater than or equal to 1:50 in vaccine