Evaluating the Safety and Immunogenicity of a Live Attenuated West Nile Virus Vaccine for West Nile Encephalitis in Adults 50 to 65 Years of Age

Inclusion Criteria: * Adult males and non-pregnant, non-breastfeeding females between 50 and 65 years of age, inclusive. Children will not be recruited or enrolled in this study for safety considerations. * Good general health, as determined by means of the screening procedures * Available for the duration of the trial * Willingness to participate in the study as evidenced by signing the informed consent form (ICF) Exclusion Criteria: * Pregnancy, as determined by positive beta-human choriogonadotropin (HCG) test (if female) * Currently lactating and breastfeeding (if female) * Participant is unwilling to use reliable contraception methods for the duration of the trial (reliable methods of birth control include: pharmacologic contraceptives including oral, parenteral, and transcutaneous delivery; condoms with spermicide; diaphragm with spermicide; surgical sterilization; intrauterine device; abstinence; and post-menopausal documented for at least 1 year). All female participants will be considered as having childbearing potential except for those with documented hysterectomy, tubal ligation, tubal coil (at least 3 months prior to vaccination), or who are post-menopausal for at least 1 year since last menstrual period. * Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, rheumatologic, autoimmune, or renal disease by history, physical examination, and/or laboratory studies * Behavioral, cognitive, or psychiatric disease that in the opinion of the in…