Safety Study of Respiratory Syncytial Virus (RSV)-Fusion (F) Protein Particle Vaccine

Inclusion Criteria: * Male or female aged 18 to 49 years inclusive * Ability to provide written informed consent to participate * Healthy, as determined by medical history, physical examination, vital signs, and clinical safety laboratory examinations at baseline * Females are required to fulfill one of the following criteria: * At least 1 year post-menopausal * Surgically sterile * Willing to use oral, implantable, transdermal or injectable contraceptives for 30 days prior to first vaccination and until 28 days after each vaccination * Willing to abstain from sexual intercourse or use another reliable form of contraception approved by the Investigator (eg, intrauterine device, female condom, and diaphragm with spermicide, cervical cap, use of condom by the sexual partner, or a sterile sexual partner) for study duration and until 28 days after vaccination * All female subjects must have a negative urine pregnancy test within 48 hours preceding receipt of each vaccination. * Comprehension of the study requirements, expressed availability for the required study period, and ability to attend scheduled visits and be contacted by telephone throughout the follow-up period Exclusion Criteria: * Presence of significant uncontrolled medical or psychiatric illness (acute or chronic). This includes institution of new medical or surgical treatment, or a significant dose alteration for uncontrolled symptoms or drug toxicity within 3 months of screening and reconfirmed on Day 1 prior to vaccination * Positive serology for HIV-1 or HIV-2, or HBsAg or HCV antibodies * Pregnant or lactating female * Females who plan to become pregnant or plan to discontinue contraceptive precautions within 30 days prior to first vaccination and 28 days after each vaccination * Cancer, or treatment for cancer, within 3 years, excluding basal cell carcinoma or squamous cell carcinoma, which is allowed * Presence of any medical condition that may be associated with impaired immune responsiveness, including diabetes mellitus * Receipt (or history of receipt), during the preceding 3-month period, of any medications or other treatments that may adversely affect the immune system such as allergy injections, immune globulin, interferon, immunomodulators, cytotoxic drugs or other drugs known to be frequently associated with significant major organ toxicity, or systemic corticosteroids (oral or injectable). Inhaled and topical corticosteroids will be allowed. * Receipt or planned administration of a nonstudy vaccine within 30 days prior to vaccination or during the study. If a nonstudy vaccine has been administered, administration of study vaccine injection can be delayed and given as soon as allowable within the 30-day window, provided the nonstudy vaccine is not administered within 2 weeks prior to study enrollment. Immunization with Tetanus Toxoids Adsorbed for adult use (Td or Tdap) vaccine, on an emergency basis, up to 8 days before or at least 8 days after a dose of study vaccine will be allowed. * History of illicit drug or alcohol abuse within the previous 1 year or positive drug or alcohol screen * History of anaphylactic type reaction to injected vaccines * Receipt of any investigational product or nonregistered drug within the 30 days prior to vaccination or current enrollment in any investigational drug study or intent to enroll in such a study within the ensuing study period * Receipt or donation of blood or blood products 8 weeks prior to vaccination or planned receipt or donation during the study period * Acute disease, defined as the presence of a moderate or severe illness (as determined by the Investigator through medical history and physical examination) with or without fever, or an oral temperature of ≥38ºC, within 72 hours prior to vaccination. Study vaccine can be administered to persons with a minor illness, such as diarrhea or mild upper respiratory tract infection with or without low-grade fever. Vaccination can be delayed until the subject has recovered. * Any condition that, in the opinion of the Investigator, would interfere with the primary study objectives