Safety and Immunogenicity of the Na-APR-1 Hookworm Vaccine in Healthy Adults

Inclusion Criteria: * Males or females between 18 and 50 years, inclusive. * Good general health as determined by means of the screening procedure. * Available for the duration of the trial (44 weeks). * Willingness to participate in the study as evidenced by signing the informed consent document. Exclusion Criteria: * Pregnancy as determined by a positive urine human choriogonadotropin (hCG) (if female). * Participant unwilling to use reliable contraception methods up until one month following the third immunization (if female and not surgically sterile, abstinent or at least 2 years post-menopausal). * Currently lactating and breast-feeding (if female). * Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, rheumatologic, autoimmune, diabetes, or renal disease by history, physical examination, and/or laboratory studies. * Known or suspected immunodeficiency. * Laboratory evidence of liver disease (alanine aminotransferase \[ALT\] greater than 1.25-times the upper reference limit). * Laboratory evidence of renal disease (serum creatinine greater than 1.25-times the upper reference limit, or more than trace protein or blood on urine dipstick testing). * Laboratory evidence of hematologic disease (hemoglobin \<11.5 g/dl \[females\] or \<12.5 g/dl \[males\]; absolute leukocyte count \<3600/mm3 or \>10.7 x 103/mm3; absolute neutrophil count \[ANC\] \<1700/ mm3; absolute lymphocyte count \<700/mm3; or platelet count \<140,000/mm3). * Laboratory evidence of a coagulopathy (PTT or PT INR greater than 1.1-times the upper reference limit). * Serum glucose (random) greater than 1.2-times the upper reference limit. * Other condition that in the opinion of the investigator would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol. * Participation in another investigational vaccine or drug trial within 30 days of starting this study. * Volunteer has had medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months. * History of a severe allergic reaction or anaphylaxis. * Severe asthma as defined by the need for daily use of inhalers or emergency clinic visit or hospitalization within 6 months of the volunteer's expected first vaccination in the study. * Positive ELISA for hepatitis B surface antigen (HBsAg). * Positive confirmatory test for HIV infection. * Positive confirmatory test for hepatitis C virus (HCV) infection. * Use of corticosteroids (excluding topical or nasal) or immunosuppressive drugs within 30 days of the volunteer's expected first vaccination in this study. * Receipt of a live vaccine within 4 weeks or a killed vaccine within 2 weeks prior to the volunteer's expected first vaccination in the study. * History of a surgical splenectomy. * Receipt of blood products within the past 6 months. * History of previous infection with hookworm or residence for more than 6 months in a hookworm-endemic area.