Safety and Immunogenicity Study of the Venezuelan Equine Encephalomyelitis Vaccine

Inclusion Criteria: * At least 18 years old * VEE PRNT80 \< 1:10 before immunization. * (females) Negative serum pregnancy test on same day before vaccination. Not planning pregnancy for 3 months. * Actively enrolled in the SIP * At risk for exposure to virulent VEE virus (with up-to-date risk assessment). * Up-to-date (within 1 year) physical examination/tests. * Sign and date the approved informed consent. * Willing to return for all follow-up visits. * Agree to report adverse event (AE) up to 28 days after vaccination. Exclusion Criteria: * Over age of 65 years. * Clinically significant abnormal lab results including evidence of Hepatitis C, Hepatitis B carrier state, or elevated liver function tests. * History of immunodeficiency or current treatment with immunosuppressive medication. * (females) Currently breastfeeding. * Confirmed human immunodeficiency virus (HIV) titer. * Family history (first degree relative, but not elderly parent with late onset) diabetes, personal history gestational diabetes, or confirmed elevated fasting serum glucose (\> 125 mg/dL). * Serious allergic reaction to guinea pigs/guinea pig products. * Any known allergies to components of the vaccine. * A medical condition that in the judgment of the Principal Investigator (PI) would impact subject safety (i.e-vaccination and or exposure to another alphavirus). * Administration of any vaccine within 28 days of TC-83. * Any unresolved AEs resulting from a previous immunization.