This is a randomized and double-blinded within study group, placebo-controlled trial to evaluate the safety, tolerability and immunological profile of INO-4500 administered by intradermal (ID) injection followed by electroporation using the CELLECTRA® 2000 device in healthy adult volunteers.

Inclusion Criteria:

• Judged to be healthy by the Investigator on the basis of medical history, physical examination and vital signs performed at Screening;
• Negative tests for Hepatitis B surface antigen (HBsAg), Hepatitis C antibody and Human Immunodeficiency Virus (HIV) antibody;
• Screening electrocardiogram (ECG) deemed by the Investigator as having no clinically significant findings (e.g. Wolff-Parkinson-White syndrome);
• Use of medically effective contraception with a failure rate of < 1% per year when used consistently and correctly from screening until 6 months following last dose or be post-menopausal or be surgically sterile or have a partner who is sterile.

Exclusion Criteria:

• Pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 1 month following last dose;
• Is currently participating in or has participated in a study with an investigational product within 30 days preceding Day 0;
• Previous receipt of an investigational vaccine product for prevention of Lassa Fever;
• Fewer than two acceptable sites available for ID injection and EP considering the deltoid and anterolateral quadriceps muscles;
• Audiometry testing that demonstrates a hearing level threshold of 30 dB or greater for any frequency tested between 250 Hz - 8000 Hz;
• Recent (within 6 months) or planned travel to Lassa-endemic region;
• Current or anticipated concomitant immunosuppressive therapy.

Data dictionaries and all collected IPD will be stripped of identifiers and may be made available upon request.

Anonymous IPD may be shared following or during the publication of summary data. Archival data may be accessed for up to 10 years following the end of the study.

Those who request the anonymous IPD must provide a plan of study explaining how the data will be used. Requests may be sent to the Central Contact Person. Requests will be reviewed based on the potential for the planned use of the IPD for advancing scientific knowledge and theory.

The Sponsor will be blinded up to Week 6; at that time the Sponsor will become group-level unblinded.