This is part of an ongoing effort to develop a satisfactory dengue vaccine:

Primary objective:

To describe the safety after each vaccination with bivalent and tetravalent formulations of dengue vaccine candidates.

To describe the immune response after each vaccination of dengue vaccine.

Subjects will be randomized to five groups to receive assigned vaccines and followed up for 12 months.

Inclusion Criteria :

• Healthy as determined by medical history, clinical examination, and biological safety parameters
• Aged 18 to 45 years on the day of inclusion.
• Informed consent form signed.
• Able to attend all scheduled visits and to comply with all trial procedures
• For a woman of child-bearing potential, use of an effective method of contraception or abstinence for at least 4 weeks prior to the first vaccination and at least 4 weeks after the last vaccination.

Exclusion Criteria :

• History of thymic diseases or thymectomy.
• For a woman of child-bearing potential, known or suspected pregnancy or positive pregnancy test
• Breast-feeding
• Current abuse of alcohol or drug addiction that may interfere with the subject's ability to comply with trial procedures.
• Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent.
• Human Immunodeficiency Virus (HIV), Hepatitis B (HBs Ag) or Hepatitis C (HC) seropositivity in blood sample taken at screening.
• Laboratory abnormalities considered clinically significant upon the Investigator's judgment or above the intensity thresholds (defined in the protocol) in blood sample taken at screening.
• Participation in another clinical trial in the 4 weeks preceding the first trial vaccination.
• Planned participation in another clinical trial during the present trial period.
• Previous residence in or travel of more than 2 weeks to areas with high dengue infection endemicity.
• Known systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to the trial vaccine or a vaccine containing the same substances (i.e. egg, egg products, proteins of rodent or neural origin, gelatin, and thimerosal.
• History of urticaria after hymenoptera envenomation.
• History of flavivirus infection as reported by the subject.
• Previous vaccination against flavivirus diseases (including Japanese encephalitis, tick-borne encephalitis, and yellow fever).
• Planned travel during the present trial period to areas with high dengue infection endemicity.
• Congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term (at least 2 weeks within the previous 3 months) systemic corticosteroid therapy (at a dose of a t least 10 mg).
• Chronic illness at a stage that could interfere with trial conduct or completion.
• Blood or blood-derived products received in the past 3 months.
• Any vaccination in the 4 weeks preceding the first trial vaccination.
• Vaccination planned in the 4 weeks following any trial vaccination.
• Flavivirus vaccination planned during the present trial period.