First in Human Dose Escalation Study Evaluating the Safety and Immunogenicity of IVT's Shigella-04 Vaccine in Healthy Young Adults

Inclusion Criteria Participants who meet all the following criteria may be included in the study: 1. Age 18 to 49 years at the time of Dose 1 2. Good general health status, as determined by medical history, physical examination, safety laboratory tests, ECG, vital signs, and clinical judgment 3. BMI ≥ 18.0 kg/m2 and ≤ 32.0 kg/m2 4. Negative alcohol breath test and urine drug screen results at Screening and on Day 1 5. All women: negative serum pregnancy test at Screening and negative urine pregnancy on Day 1 6. Women of childbearing potential (see definition in Section 6.6.1): willingness to use a highly effective form of contraception (see list in Section 6.6.1) through 28 days after the last IP dose 7. Willingness to attend all protocol visits and to have all protocol-required procedures 8. Provision of written informed consent Exclusion Criteria Participants who meet any of the following criteria will be excluded from the study: 1. Currently lactating 2. History of shigellosis or participation in a Shigella challenge study 3. History of bloody diarrhea without alternative diagnosis 4. History of inflammatory bowel disease 5. History of anaphylaxis or angioedema 6. History of malignancy, excluding nonmelanoma skin cancer, cervical carcinoma in situ, and malignancies considered cured \> 5 years prior to Day 1 7. History of diabetes mellitus (Individuals with diet-controlled diabetes or history of gestational diabetes are eligible if screening blood glucose is normal and there has been no requirement for antidiabetic medication in the last year.) 8. Known hypersensitivity to any of the ingredients in IVT Shigella-04 9. Inadequate venous access for repeated phlebotomy 10. Any screening laboratory test result outside the normal range and grade ≥ 2 according to the FDA's toxicity grading scale for vaccine trials in healthy adults and adolescents; (Elevated creatine kinase and isolated elevations of bilirubin may be Grade 2 if hepatic transaminases are normal and the Investigator attributes the abnormality to exercise or Gilbert's syndrome. Potential cases of benign ethnic neutropenia should be discussed with the Medical Monitor) 11. Positive serologic test for human HIV-1 or HIV-2 antibody, hepatitis B surface antigen, or hepatitis C antibody 12. Immunodeficiency or chronic administration (\> 14 consecutive days) of immunosuppressant or other immune-modifying drugs (see details in Section 6.6.2), including systemic glucocorticoids, within 6 months before Day 1 (topical, intra-articular, or inhaled glucocorticoids permitted) 13. Previous receipt of a licensed or investigational Shigella vaccine 14. Planned receipt of any other vaccine through Day 57 15. Receipt of blood transfusion or blood product within 6 months before Day 1 or planned receipt through Day 57 16. Receipt of any other IP within 90 days before Day 1 or planned receipt through the end of the study 17. Planned elective hospitalization or surgical procedure through the end of the study 18. Occupational exposure to Shigella (eg, laboratory work) 19. Residence ≥ 6 months in a low-income or lower-middle-income country as defined by the World Bank (https://datatopics.worldbank.org/world-development-indicators/the-world-by-income-and-region.html) 20. Employee of Inventprise, vendors, or research sites associated with the study 21. Any medical, psychiatric, substance use, or social condition that, in the judgment of the Investigator, may pose a risk to the participant or interfere with protocol adherence, assessment of study objectives, or ability to provide informed consent Temporary Delay Criteria Administration of IVT Shigella-04/placebo will be delayed for any participant who meets any of the following criteria: 1. Receipt of any vaccine in the past 7 days 2. Febrile illness (eg, oral temperature ≥ 38.0°C), diarrhea, or other acute illness in the past 48 hours 3. Presence of any other sign, symptom, or medication use that could inhibit the proper vaccine administration of IVT Shigella-04/placebo or interpretation of diary data These criteria are temporary or self-limiting, and IVT Shigella-04/placebo may be administered once the time frame has elapsed/the condition has resolved.