A Phase 1, Dose Escalation Study, to Evaluate a New Shigella Sonnei Vaccine in Healthy Adults.

Inclusion Criteria: 1. Males and females of age ≥18 years to ≤45 years. 2. Individuals who, after the nature of the study has been explained to them, and prior to any protocol specific procedures being performed, have given written consent according to local regulatory requirements. 3. Individuals in good health as determined by the outcome of medical history, physical examination, hematological / hematochemical blood tests (including presence of high antibody titers against S. sonnei by agglutination test), urinalysis and clinical judgment of the investigator. 4. If women of child-bearing potential, have a negative pregnancy test prior study vaccination and willingness to use acceptable birth control measures for the entire study duration. 5. Individuals affiliated to a social security regimen. Exclusion Criteria: 1. Individuals with behavioral or cognitive impairment or psychiatric disease that, in the opinion of the investigator, may interfere with the subject's ability to participate in the study. 2. Individuals with any progressive or severe neurological disorder, seizure disorder or Guillain-Barré syndrome. 3. Individuals who are not able to understand and to follow all required study procedures for the whole period of the study. 4. Individuals with history of any illness that, in the opinion of the investigator, might interfere with the results of the study or pose additional risk to the subjects due to participation in the study. 5. Individuals human leukocyte antigen (HLA) -B27 positive and/or with history of reactive arthritis. 6. Individuals with known or suspected HIV infection or HIV related disease, with history of an autoimmune disorder or any other known or suspected impairment /alteration of the immune system, or under immunosuppressive therapy including use of systemic corticosteroids or chronic use of inhaled high-potency corticosteroids (i.e. prednisone, or equivalent ≥10 mg/day) within the previous 28 days, or in chemotherapy treatment within the past 168 days. 7. Individuals with a known bleeding diathesis, or any condition that may be associated with a prolonged bleeding time. 8. Individuals with any serious chronic or progressive disease according to judgment of the investigator (e.g., neoplasm, insulin dependent diabetes, cardiac, renal or hepatic disease). 9. Individuals who have any malignancy or lymphoproliferative disorder. 10. Individuals with history of allergy to vaccine components. 11. Individuals participating in any clinical trial with another investigational product 28 days prior to first study visit or intent to participate in another clinical study at any time during the conduct of this study. 12. Individuals who received any other vaccines within 4 weeks prior to enrollment in this study or who are planning to receive any vaccine within the entire study duration except influenza vaccination, which is not allowed within the period included between 28 days before 1st vaccination and 28 days after 3rd vaccination. 13. Individuals who have received blood, blood products, and/or plasma derivatives including parenteral immunoglobulin preparations in the past 12 weeks. 14. Individuals who are part of study personnel or close family members to the personnel conducting this study or employees of the clinical trial site institution. 15. Individuals with body temperature \> 38.0 degrees Celsius within 3 days of intended study vaccination. 16. Individuals with Body Mass Index (BMI)\> 30 kg/m2 17. Individuals with history of substance or alcohol abuse within the past 2 years. 18. Women who are pregnant or are breast-feeding, or are of childbearing age who have not used or do not plan to use acceptable birth control measures, for the duration of the study. 19. Females with history of stillbirth, neonatal loss, or previous infant with anomaly. 20. Individuals who have a previously laboratory confirmed or suspected disease caused by S. sonnei. 21. Individuals who have had household contact with/and or intimate exposure to an individual with laboratory confirmed S. sonnei. 22. Any condition, which, in the opinion of the investigator may pose an increased and unreasonable safety risk to the subject if participating to the present study