Inclusion Criteria:

1. Between 18 and 45 years of age, inclusive
2. Good general health without significant physical examination findings or clinically significant abnormal laboratory results
3. Available to participate for the entire study period of approximately 12 months
4. For women of childbearing potential, a negative urine pregnancy test at screening and before each immunization, and agreement to consistently use contraception from 28 days prior to enrollment until the last protocol visit, for sexual activity that could lead to pregnancy

5. Acceptable laboratory parameters:

   • negative CMV serology
   • hemoglobin ≥ 11.2 g/dL for women, ≥ 12.8 g/dL for men
   • white blood cell count 3,300 - 12,000 cells/mm3
   • platelet count 125,000 - 550,000/mm3
   • alanine aminotransferase (ALT) within normal range for study laboratory
   • serum creatinine within normal range for study laboratory
   • normal urine dipstick (negative glucose, negative hemoglobin, and negative or trace protein)
   • negative hepatitis B virus (HBV) and hepatitis C virus (HCV) blood tests
   • negative HIV blood test
6. Willingness to have blood stored for up to 10 years for use in additional assays to evaluate immune responses to CMV or the alphavirus vector if such assays become available
7. Willingness to participate in the study as evidenced by signed informed consent obtained before screening

Exclusion Criteria:

1. Venous access deemed inadequate for the phlebotomy demands of the study
2. Women who are breast feeding
3. In female subjects, a positive urine pregnancy test at screening or on the day of any vaccine injection
4. Receipt of any vaccine within 30 days prior to enrollment
5. Use of any investigational agent within 30 days prior to enrollment
6. Receipt of immunoglobulin or blood products within 60 days prior to enrollment
7. Use of cytotoxic medications within 6 months prior to enrollment
8. Use of systemic corticosteroids within 6 months prior to enrollment (except that participants who have completed a course of prednisone, at up to 20 mg per day for up to 7 days, at least 1 month prior to enrollment are eligible for enrollment)
9. History of serious adverse reactions to any vaccine, including anaphylaxis and related symptoms such as hives, respiratory difficulty, angioedema or abdominal pain
10. History of immunodeficiency or autoimmune disease
11. History of diabetes mellitus
12. History of splenectomy
13. History of malignancy within the last 3 years (except that participants with a diagnosis of basal cell carcinoma of the skin are eligible for enrollment)

14. Psychiatric condition that may interfere with the ability to comply with the protocol requirements.

    Specifically excluded are persons with history of psychosis within the past 3 years or history of suicidal attempt or gesture within the past 3 years.

15. History of medical, occupational or family problems as a result of alcohol or illicit drug use during the past 12 months
16. Any condition which leads the investigator to believe that the participant cannot comply with the protocol requirements or that may place the participant at an unacceptable risk for participation