This is a randomized, placebo-controlled dose-escalation study. The main purpose of this research is to test the safety and measure the immune response of the trivalent vaccine against invasive Salmonella disease. The vaccine will be tested over a range of doses.

Inclusion Criteria:

• Ability to provide written informed consent
• Age 18 - 45 years, inclusive
• Good general health as determined by: vital signs (heart rate <100 bpm; blood pressure systolic >90 mm Hg and ≤150 mm Hg; diastolic >45 mm Hg and ≤90 mm Hg; oral temperature <100.4ºF), medical history, and a physical examination† within 45 days before administration of first dose of vaccine.
• Expressed interest and availability to fulfill the study requirements
• For females of child-bearing potential*, must agree to acceptable birth control&, 4 weeks before enrollment and through 4 weeks after last vaccination.
• Agrees not to participate in another clinical trial at any time during the study period.
• Agrees to allow for the indefinite storage of blood samples for future research use.

Exclusion Criteria:

• History of typhoid vaccination or known history of typhoid infection within 5 years

• Unacceptable laboratory abnormality from screening (prior to first vaccination) or upon safety laboratory testing (prior to second vaccination) as listed below. Laboratories with abnormalities which are possibly transient in nature may be repeated one time.

  1. Hemoglobin, white blood cell (WBC) count, absolute neutrophil count (ANC), or platelet count of an unacceptable value, according to Appendix B
  2. Creatinine, AST, ALT, total bilirubin, or C-reactive protein of an unacceptable value, according to Appendix B
  3. Positive serology for hepatitis C or HIV antibody or hepatitis B surface antigen.

(Subjects will be informed if their results are positive for hepatitis C, HIV antibody or hepatitis B surface antigen and will be referred to a primary care provider for follow up of these abnormal laboratory tests.)

• For women of child-bearing potential, positive serum pregnancy test (during screening within 45 days of enrollment) or positive urine pregnancy test (prior to and within 24 hours of administering each dose of vaccine).
• Nursing mother.
• Temperature > 38.0°C (100.4°F) or symptoms of an acute self-limited illness such as an upper respiratory infection or gastroenteritis within 3 days prior to each dose of vaccine.
• Medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months.
• Diagnosis of schizophrenia or other major psychiatric disease
• Failure to pass Comprehension Assessment Tool during screening (70% correct answers are required to pass).
• Receipt of an experimental agent (vaccine, drug, device, etc.) within 28 days before enrollment or expects to receive an experimental agent during the study period.
• Receipt of any licensed vaccine within 2 weeks (for inactivated vaccines) or 4 weeks (for live vaccines) before enrollment in this study.
• Known sensitivity to any ingredient in the study vaccine, including a history of severe allergic reaction to tetanus vaccine.
• Receipt of immunoglobulin or other blood product within the 3 months prior to vaccination in this study.
• Immunosuppression as a result of an underlying illness or treatment with immunosuppressive or cytotoxic drugs, or use of anticancer chemotherapy or radiation therapy within the preceding 36 months.
• Long-term use (>2 weeks) of oral or parenteral steroids (glucocorticoids), or high-dose inhaled steroids (>800 mcg/day of beclomethasone dipropionate or equivalent) within the preceding 6 months (nasal and topical steroids are allowed).
• Other condition that in the opinion of the investigator would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol.