Safety and Immunogenicity Study of Recombinant Ricin Toxin A-Chain Vaccine (RVEc™)

Inclusion Criteria:

- Study subjects must be 18-50 years old.

- Subjects must weigh at least 110 pounds.

- Subjects must be in good health as judged from medical history, physical examination,
EKG and chest x-ray, complete blood count (CBC) with differential, clinical
chemistries, urinalysis, hepatitis serology, and HIV antibody test, and be medically
cleared for participation by an investigator. If any HIV or hepatitis testing is
positive, the individual will be provided with counseling and referral for health
care.

- Females of childbearing potential must have a negative pregnancy test on vaccination
day before each dose and agree to not become pregnant or breastfeed for 3 months
after the last dose of the vaccine and be willing to use a reliable form of
contraception during the study.

- Study subjects must read and sign an approved informed consent.

- Study subjects must be willing to complete a subject diary card after each
vaccination.

- Study subjects must be willing to return for all follow-up visits.

- Study subjects must agree to report any adverse event (AE) that may or may not be
associated with administration of the investigational product through the 9-month
follow-up visit. Study subjects will report all serious adverse events for the
duration of the study.

Exclusion Criteria:

- Body weight less than 110 pounds.

- Acute or chronic medical conditions or immunodeficiency from a medical condition or
medical treatment, medications, or dietary supplements that, in the investigator's
opinion, would impair the subject's ability to respond to vaccination.

- Severe hypersensitivity to any vaccine (anaphylaxis, angioedema, bronchospasm, or
laryngospasm).

- History of asthma, chronic obstructive pulmonary disease, or other current/residual
disease of the lungs.

- Clinically significant abnormal laboratory tests.

- Current smoker.

- Any known allergies to sodium succinate, Tween-20 (a detergent), aluminum hydroxide,
or kanamycin.

- Previously received ricin toxin vaccine or has antibodies to ricin toxin proteins.

- Receipt of licensed vaccines within 30 days prior to the start of the study or plans
to receive other vaccines during the initial 9 months of the study (the only
exceptions are the inactivated influenza vaccine that can be received at least 30
days after RVEc Dose 3).

- Receipt of investigational drug/test product within 30 days prior to entry or within
the initial 9 months of the study.

- Females: Pregnant or breastfeeding.

- Enrolled in another greater than minimal risk study.