Efficacy of Na-GST-1/Alhydrogel Hookworm Vaccine Assessed by Controlled Challenge Infection

Inclusion Criteria: 1. Males and non-pregnant females between 18 and 45 years, inclusive. 2. Good general health as determined by means of the screening procedures1. 3. Available for the duration of individual subject study participation (14 months). 4. Willingness to participate in the study as evidenced by signing the informed consent document. 5. Able to understand and comply with planned study procedures. Exclusion Criteria: 1. Pregnancy as determined by a positive urine human choriogonadotropin (hCG) test (if female). 2. Subject unwilling to use effective contraception for a minimum of 30 days prior to vaccination and up until documentation of clearance of hookworm infection post-CHHI (if female and not surgically sterile, abstinent from intercourse with a male partner, in a monogamous relationship with a vasectomized partner, at least 2 years post-menopausal, or determined otherwise by medical evaluation to be sterile). 3. Currently lactating and breast-feeding or plans to breastfeed at any given time from the first study vaccination until clearance of hookworm infection post-CHHI (if female). 4. Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, rheumatologic, autoimmune, gastrointestinal, diabetes, or renal disease by history, physical examination, and/or laboratory studies. 5. 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). 6. Known or suspected immunodeficiency or immunosuppression as a result of an underlying illness or treatment (causes for immunosuppression may include, but are not limited to, poorly-controlled diabetes mellitus, chronic liver disease, renal insufficiency, active neoplastic disease or a history of hematologic malignancy, connective tissue disease, organ transplant). 7. Laboratory evidence of liver disease (alanine aminotransferase \[ALT\] greater than 1.25-times the upper reference limit). 8. Laboratory evidence of renal disease (serum creatinine greater than 1.25-times the upper reference limit, or urine dipstick testing positive for glucose or more than trace protein). 9. 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; absolute eosinophil count \<500/mm3; or platelet count \<140,000/mm3). 10. 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. 11. Planned participation in another investigational vaccine or drug trial within 30 days of starting this study or until the last study visit (this may include other licensed or unlicensed vaccines, drugs, biologics, devices, blood products, or medications). 12. Volunteer has had medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 24 months. 13. Positive fecal occult blood test at screening. 14. Infection with a pathogenic intestinal helminth as determined by stool examination for ova and parasites at screening. 15. History of iron deficiency anemia or laboratory evidence of iron deficiency (serum ferritin concentration below the lower reference limit). 16. History of hypoalbuminemia. 17. History of a severe allergic reaction or anaphylaxis. 18. 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. 19. Positive test for hepatitis B surface antigen (HBsAg). 20. Positive confirmatory test for HIV infection. 21. Positive confirmatory test for hepatitis C virus (HCV) infection. 22. Using or intends to continue using oral or parenteral corticosteroids, high-dose inhaled corticosteroids (\>800 μg/day of beclomethasone dipropionate or equivalent) or other immunosuppressive or cytotoxic drugs within 30 days of the volunteer's expected first vaccination in this study or planned use during the study. 23. 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. 24. Receipt of immunoglobin or other blood products (with exception of Rho D immunoglobulin) within 90 days of the planned first study vaccination. 25. Known allergy to albendazole, amphotericin B or gentamicin. 26. History of previous infection with hookworm or continuous residence for more than 6 months in a community where hookworm is endemic. 27. Current or past scars, tattoos, or other disruptions of skin integrity at the intended site of larval application. 28. Previous receipt of the Na-GST-1/Alhydrogel® hookworm vaccine. 29. History of a surgical splenectomy. 30. 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, and/or proteinuria (greater than trace protein on urine dipstick testing).