Immunogenicity, Safety, and Tolerability of rF1V-1018 Vaccine in Adults 18 to 55 Years of Age

Inclusion Criteria:

1. Adults 18 to 55 years of age

2. Healthy participants or participants with stable pre-existing medical conditionsPre-existing stable medical condition means a participant who: has full capacity ofdaily activity and no major medication modification within 3 months prior to Day 1;has not undergone surgical or minimally-invasive intervention or had anyhospitalization/emergency room visit for the specific medical condition.

3. Able to comply with the protocol schedule and procedures

4. Able and willing to provide written informed consent

5. If female of child-bearing potential and heterosexually active, has practicedadequate contraception for at least 28 days prior to vaccination, has negativepregnancy tests just prior to vaccination, and has agreed to continue adequatecontraception through three months following the final trial injection

A premenopausal woman who has at least one of the following is considered not of childbearing potential:

1. Documented hysterectomy

2. Documented bilateral salpingectomy

3. Documented bilateral oophorectomy

4. Documented and current bilateral tubal ligation or occlusion

Exclusion Criteria:

1. A history of plague disease or have previously received any plague vaccine

2. Active tuberculosis or other systemic infectious process

3. History of human immunodeficiency virus (HIV), hepatitis B (HBV) or hepatitis C (HCV) infection, or positive test for antibody to HIV, HBV, or HCV

4. History of autoimmune disorder

5. History of sensitivity to any component of trial vaccines

6. Body mass index ≥ 30 kg/m2

7. Has received the following prior to any trial injection: a) ≤ 14 days: i) Any licensed or authorized inactivated vaccines (including vaccinescontaining mRNA or CpG) b) ≤ 28 days: i) Any live vaccine ii) Any investigationalmedicinal agent c) ≤ 90 days: i) Chronic administration (defined as more than 14consecutive days in total) of immunosuppressants or other immune-modifying drugsduring the period starting 90 days prior to the first trial vaccine administrationor planned administration during the trial period. (For corticosteroids, this willmean prednisone ≥20 mg/day, or equivalent). Inhaled, topical, and intraarticularsteroids are allowed. ii) Granulocyte or granulocyte-macrophage colony stimulating factor iii)Immunoglobulins or any blood products (receipt of certain monoclonal antibodies mayon a case-by-case basis be non-exclusionary if approved via consultation withSponsor Medical Monitor) iv) Antisense oligonucleotides v) Drugs/investigationalagents with very long half-lives (defined as ≥ 60 days) (eg, radioactive iodine,amiodarone, liraglutide, nirsevimab, teplizumab, evinacumab, and obinutuzumab) vi)Infusion of blood products d) At any time: DNA plasmids or other genetic therapyintended to integrate permanently into host cells

8. If female is pregnant (known before or established at the time of screening),breastfeeding, or planning breastfeeding or a pregnancy

9. Is undergoing chemotherapy or expected to receive chemotherapy during the trialperiod; has a diagnosis of cancer within the last 5 years other than squamous cellor basal cell carcinoma of the skin

10. History or current evidence of any condition, therapy, or laboratory abnormalitythat might confound the results of the trial, interfere with participation for thefull duration of the trial, or is not in the best interest of the participant toparticipate, in the opinion of the treating investigator

11. Oral temperature ≥ 38°C (≥ 100.4°F) at the time of vaccine administration

12. History of acute myocardial infarction (AMI) or documented coronary artery disease (CAD)