Safety and Immunogenicity Study of Na-GST-1 With or Without CpG

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 (68 weeks). * Willingness to participate in the study as evidenced by signing the informed consent document. * Able to understand and comply with planned study procedures. Exclusion Criteria: * Pregnancy as determined by a positive urine human choriogonadotropin (hCG) test (if female). * Participant unwilling to use reliable contraception up until one month following the third immunization (if female and not surgically sterile, abstinent, at least 2 years post-menopausal, or determined otherwise by medical evaluation to be sterile). * 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. A history of essential hypertension that is well controlled by medication will not be considered exclusionary. * Has a diagnosis of schizophrenia, bipolar disease or other major psychiatric condition that would make compliance with study visits/procedures difficult (e.g., subject with psychoses or history of suicide attempt or gesture in the 3 years before study entry, ongoing risk for suicide). * 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 with the exception of greater than 1+ blood detected in females during menses). * Laboratory evidence of hematologic disease (hemoglobin \<11.1 g/dl \[females\] or \<12.5 g/dl \[males\]; absolute leukocyte count \<3400/mm3 or \>10.8 x 103/mm3; or platelet count \<140,000/mm3). * Laboratory evidence of a coagulopathy (activated PTT or PT INR greater than 1.1-times the upper reference limit). * Serum glucose 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. * Planned participation in another investigational vaccine or drug trial within 30 days of starting this study or until Visit #17 (6 months after the third vaccination). * 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 test 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 or planned use up to one month following the last vaccination. * 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. * Previous receipt of the Na-GST-1/Alhydrogel® hookworm vaccine. * History of a surgical splenectomy. * Receipt of blood products within the past 6 months. * Pre-existing autoimmune or antibody-mediated diseases including but not limited to: systemic lupus erythematosis, rheumatoid arthritis, multiple sclerosis, Sjogren's syndrome, autoimmune thrombocytopenia; or laboratory evidence of possible autoimmune disease determined by a positive anti-dsDNA titer, positive rheumatoid factor, proteinuria and/or a positive ANA. * History of previous infection with hookworm or residence for more than 6 months in a community where hookworm is endemic.