A randomized 4 cohort study that is comparing the data collected during the earlier phase study and to determine if immunogenicity can be retained with a 1 mg dose of Hantaan DNA vaccine. The study is intended to substantiate the Phase 1 results with the 2 mg dose and to also determine if immunogenicity can be retained with a 1 mg dose (for HTNV DNA vaccine).

The study will enroll 4 randomized groups of 33 subjects each for a total of 132 subjects. Every subject will receive a total of 4 vaccinations. Subjects and study personnel will be blinded to the group that they are randomized to (double-blind). The study is intended to substantiate the Phase 1 results with the 2 mg dose and to also determine if immunogenicity can be retained with a 1 mg dose (for HTNV DNA vaccine).

For the 2 mg dose, each vaccination consists of 2 administrations of 1 mg (left and right deltoid) for a total of 2 mg/vaccination. For the 1 mg dose, each vaccination consists of 2 administrations of 0.5 mg (left and right deltoid) for a total of 1 mg/vaccination.

Group 1 will be vaccinated with the HTNV DNA vaccine, pWRG/HTN-M(co) at the 2 mg/vaccination dose. Group 2 will be vaccinated with the HTNV DNA vaccine, pWRG/HTN-M(co) at the 1 mg/vaccination dose. Group 3 will be vaccinated with the PUUV DNA vaccine, pWRG/PUU-M(s2) at the 2 mg/vaccination dose. Group 4 will be vaccinated with the PUUV DNA vaccine, pWRG/PUU-M(s2) at the 1 mg/vaccination dose. Each group will be vaccinated on Days 1, 29, 57 and 169. All doses will be administered with the PharmaJet Stratis device, which is FDA cleared for IM administration of vaccines. All subjects will be followed until 6 months (month defined as 28 days) after the last vaccination with Day 337 being the final study visit. Subjects will complete post-injection memory aids for 7 days after each vaccination.

Inclusion Criteria:

Subjects must meet all of the following criteria to be included in the study:

1. Healthy adult male or nonpregnant, nonlactating female, ages 18-49 (inclusive) at the time of screening

2. Have provided written informed consent before screening

3. Completion of written test called the 'Assessment of Understanding' (minimum passing score of 80% with 2 attempts permitted).

4. A subject must have a valid state or government-issued photo ID (eg, driver's license, military ID, or U.S. passport) & be able to pass a background check in order to gain access to the base & participate.

5. In general, good health without clinically significant medical problems, as determined by pertinent medical history and clinical examination and laboratory assessments prior to entry into the study.

6. Available and able to participate for all study visits and procedures

7. Females subjects must have had a hysterectomy or bilateral oopherectomy or must be using an effective method of contraception** from 30 days prior to the first study vaccination until 90 days after the last study vaccination.

   ** For this study, we define an effective contraceptive method as one that results in a failure rate of less than 1% per year when it is used consistently and correctly. This includes, but is not limited to, abstinence from sexual intercourse with a male partner, monogamous relationship with a vasectomized partner, bilateral tubal ligation, or intrauterine devices.

8. Female subjects who have not had a hysterectomy or bilateral oopherectomy must have a negative serum pregnancy test at screening and a negative urine pregnancy test within 24 hours prior to each study vaccination.

9. Sexually active male participants whose partner is a woman who has not had a hysterectomy or bilateral oopherectomy and has not had a vasectomy** must agree not to father a child until 90 days after the last vaccination.

   ** performed > 1 year prior to screening

10. Women agree to not donate eggs (ova, oocytes) and male subject agrees not to donate sperm from the start of screening onwards until at least 90 days after the last vaccination.

11. Agree not to participate in another clinical trial during the study period.

12. Agree not to donate blood to a blood bank for 3 months after receiving the last study vaccine.

13. Have acceptable screening laboratory tests* within 90 days prior to enrollment. Refer to Appendix A for range of acceptable laboratory values. Screening laboratory values that are outside acceptable range but are thought to be due to an acute condition or due to laboratory error may be repeated once. [see Manual of Procedures (MOP)]

14. Negative HIV testing (HIV Ab / antigen 4th generation screen with reflex confirmatory RNA testing).

15. Negative hepatitis B surface antigen (HBsAg) and hepatitis C antibody testing.

Exclusion Criteria:

Subjects meeting any of the following criteria will be excluded from the study:

1. History of previous hantavirus vaccine.

2. History of severe local or systemic reactions to any vaccination or a history of severe allergic reactions

3. Ongoing participation in another clinical trial (those continuing through Day 337 will not join other new studies until their final visit)

4. Receipt of licensed vaccines within 7 days before or after immunization (30 days for live vaccines)

5. Any use of investigational drugs or vaccines within 30 days before starting the study.

6. Ability to observe possible local reactions at the eligible injection sites (deltoid region) is, in the opinion of the investigator, unacceptably obscured due to a physical condition or permanent body art.

7. Acute or chronic, clinically significant hematologic, pulmonary, cardiovascular, or hepatic or renal functional abnormality as determined by the investigator based on medical history, physical exam, and/or laboratory screening test

8. Pregnant or lactating female, or female who intends to become pregnant during the study period

9. Administration of immunoglobulins and/or any blood products within the 120 days preceding study entry or planned administration during the study period

10. Blood donation for human use (eg, American Red Cross or other similar blood drives) within the 56 days preceding study entry or planned administration during the study period

11. Any confirmed evidence of hepatitis B or C infection

12. Have an acute illness*, as determined by the site PI or appropriate sub-investigator, within 72 hours prior to study vaccination.

    *An acute illness which is nearly resolved with only minor residual symptoms remaining is allowable if, in the opinion of the site PI or appropriate sub-investigator, the residual symptoms will not interfere with the ability to assess safety parameters as required by the protocol. Subjects may re-screen after an acute illness is resolved

13. Any confirmed or suspected immunosuppressive or immunodeficient condition or use of anticancer chemotherapy or radiation therapy (cytotoxic) within 3 years prior to study vaccination.

14. Administration of chronic (defined as more than 14 days) immunosuppressants* or other immune-modifying drugs within 6 months of study entry

    • For corticosteroids, this will mean prednisone, or equivalent, greater than or equal to 0.5 mg/kg/day
    • Intranasal, inhaled, and topical steroids are allowed

15. Any chronic or active neurologic disorder, including seizures and epilepsy, excluding a single febrile seizure as a child and intermittent non migraine headaches

16. Have any diagnosis, current or past, of schizophrenia, bipolar disease, or other psychiatric diagnosis that may interfere with subject compliance or safety evaluations.

17. Have been hospitalized for psychiatric illness, history of suicide attempt, or confinement for danger to self or others within 10 years prior to study vaccination.

18. Suspected or known current alcohol or drug abuse that in the opinion of the investigator could impact subject safety, interpretation of adverse events or ability to follow up.

19. Have any plan to have major surgery that, in the opinion of the investigator, could impact subject safety or interpretation of adverse events between enrollment and the end of the study.

20. A diagnosis of Type I or II diabetes.

21. Unwilling to allow storage and use of blood for future hantavirus-related research (for monoclonal antibody development, and crossreactivity to other hantaviruses).

22. Any other significant finding that in the opinion of the investigator would increase the risk of the individual having an adverse outcome from participating in this study.

Elimination Criteria:

The following criteria will be assessed at enrollment and prior to each vaccination, to determine whether or not the subject will be eliminated from the "according to protocol" analysis. On the basis of these criteria the subject may be disqualified from further vaccination or from any other aspect of the clinical trial procedures as judged appropriate by study investigators. A subject meeting any of the following criteria will still be followed for safety, unless the subject chooses to have complete withdrawal of the consent for further participation in any trial procedures.

1. Use of any investigational drug or vaccine other than the study vaccine(s) during the study period.
2. Receipt of a licensed vaccine within 7 days prior to or 7 days after vaccination (30 days for live vaccines).
3. Administration of chronic (defined as more than 14 days) immunosuppressive drugs (including oral steroids in doses that are the same as those listed in the exclusion criteria) or other immune modifying drugs.
4. Administration of immunoglobulins and/or any blood products during the study period.
5. Known intravenous drug abuse evident through subject history or on physical exam.
6. Poor reliability, inability to keep appointments, or other protocol violation.
7. Any other significant finding that in the opinion of the investigator would increase the risk of having an adverse outcome as a result of continued participation in this study.

Investigators will eliminate a subject from the study prior to first vaccination if the subject is found to have met any exclusion criteria in the time leading up to vaccination.

Double-blind Study