To evaluate and compare the immune responses and safety following a two vaccination regimen by transcutaneous immunization with heat-labile enterotoxin of E. coli (LT) patches or placebo patches.

Inclusion Criteria:

• Healthy adult males or females, 18-64 years of age (inclusive) at the planned start of the study (first vaccination on Day 0)
• Signed Informed Consent
• Women who are not post-menopausal or surgically sterile must have a negative serum/urine pregnancy test at screening and within 24 hours of each vaccination with understanding (through Informed Consent process) to not become pregnant and to employ an effective form of birth control for the duration of the study. Acceptable forms of birth control are: abstinence, hormonal contraceptives (oral, injectable, implant, patch, ring), double-barrier contraceptives (condom or diaphragm, with spermicide), and IUD.

Exclusion Criteria:

• Laboratory abnormalities [as determined by the Toxicity Grading Scale (grade 1 4)] at laboratory screening
• Abnormalities at physical examination [as determined by the Toxicity Grading Scale (grade 1-4)]
• Known allergies to any component of the vaccine
• Known allergies to adhesives
• Participated in research involving investigational product within 30 days before planned date of first vaccination or within 90 days after first vaccination
• Donated blood or blood products such as plasma within 30 days prior to planned date of first vaccination or within 90 days after first vaccination
• Ever received investigational enterotoxigenic E. coli, LT, or LT (R192G) or NasalFlu, Berna Biotech, Ltd
• Ever received cholera toxin or vaccine (e.g. Orochol™, Dukoral™)
• History of diarrhea while traveling in a developing country within the last year
• History of abdominal surgery (excluding C-section, hysterectomy, cosmetic surgery, liposuction, appendectomy, cholecystectomy, ventral hernia repair, and other surgeries not pertaining to gastrointestinal problems) or history of, or recent acute gastrointestinal illness
• Positive serology for HIV-1, HIV-2, HBsAg, or HCV
• Medical history of acute or chronic skin disease at vaccination area(s)
• Active skin allergy
• Signs of acute skin infection, sunburn or skin abnormalities at the vaccination area(s) including fungal infections, severe acne, or active contact dermatitis, or a history of keloid formation
• Excessively hirsute and unwilling to clip hair at the vaccination area(s)
• Visible tattoos or marks (tattoos/scars) at the vaccination area(s) that would prevent appropriate dermatologic monitoring of the vaccination site(s)
• Fever greater than or equal to 38.0°C (100.4°F) at the time of planned vaccination
• Women who are pregnant or breastfeeding
• Acute illness at screening and unresolved at time of planned vaccination
• Employee of the investigational site

Intent-to-Treat (ITT) Population: all study subjects who were consented, randomized, and had a baseline serology