Dose-finding Study of WS6788A, DS37-4 and H10407 Enterotoxigenic Escherichia Coli (ETEC) Challenge Strains

The rationale for validation H10407 in the challenge study proposed at Johns Hopkins University is that this initial challenge study will support additional challenge studies planned for the future. In these future studies, a bovine milk immunoglobulin containing high levels of antibodies specific for colonization factor antigen (CFA/I) or CFA/I-derived colonization factor will be investigated as a potential oral prophylaxis to neutralize subsequent challenge against CFA/I-expressing H10407 in the clinical setting. The goal here is therefore to validate a challenge dose of 1x109 h10407 organisms in the hands of the Johns Hopkins investigative team and to then use this dose in the future prophylaxis/challenge studies. Challenge doses equal to or comparable to the 1x109 dose proposed for the Johns Hopkins University (JHU) study have been used in 6 of the 9 challenge studies that have been done with the H10407 strain. The subsequent challenge studies using H10407 will be registered as part of other protocols.

Inclusion criteria

• Healthy adults age 18 to 45 years old who are willing to participate, complete training on ETEC and diarrhea and procedures of the protocol, pass the test documenting knowledge of the study, and give informed consent.

Exclusion criteria

• age<18 or >45 years
• Chronic illness, chemical dependency, or significant medical illness as determined by the investigator.
• immunosuppressive condition or IgA (Immunoglobulin A) deficiency
• HIV antibody positive
• hepatitis B surface antigen positive
• hepatitis C antibody positive
• travel to ETEC endemic area within 2 years
• vaccination or other exposure to ETEC, cholera, or heat labile toxin (LT) toxin within 3 years
• pregnancy as defined by + serum or urine - human chorionic gonadotropin (HCG) on the day before immunization
• inability to pass the written examination
• use of antibiotic, H2 blocking agent or proton pump inhibitor within 7 days of challenge
• regular use of laxatives antacids or other agents to lower stomach acidity
• significant abnormality in screening lav hematology and chemistry tests as determined by the investigator.
• significant abnormality on EKG for those 40 to 50 years old as determined by the investigator.
• allergy to quinolones, penicillin's and Bactrim.
• abnormal stool pattern (fewer than 3 stools per week or more than 3 stools per day).