This is a research study about an experimental (investigational) oral ETEC vaccine (ACE527). ACE527 is a live attenuated vaccine that is being made to prevent disease from enterotoxigenic Escherichia coli (ETEC), which causes watery diarrhea, largely in children living in developing countries and in travelers to those countries. This research study is also testing an investigational adjuvant called dmLT. An adjuvant is something that is added to a vaccine to make it work better. The purpose of this study is two-fold. First, Part A aims to find out if the vaccine by itself or the vaccine combined with the adjuvant is safe, tolerable, and initiates an immune response. Second, Part B aims to find out if the vaccine by itself or the vaccine combined with the adjuvant prevents diarrheal disease when challenged with ETEC H10407. About 60 healthy adults, ages 18-50, will participate in Part A, and they will be required to stay in the research facility for several nights for the first dose, but will not be required to stay overnight for the second and third doses. Participants will be assigned to receive either the vaccine alone, the vaccine with adjuvant, or placebo by mouth. Study procedures include: stool samples, blood samples, and documentation of side effects. Participants will be involved in study related procedures for about 8 months. Interested volunteers from Part A will along with volunteers who were never vaccinated in Part A will return to participate in Part B. These volunteers will be required to stay overnight in the research facility for several nights after challenge, after which they will be treated with antibiotics and sent home. Study procedures include stool samples, blood samples, and documentation of infection with ETEC H10407. If the vaccine with/without adjuvant is effective, the volunteers should not development diarrhea, but if the vaccine with/without adjuvant is not effective, the volunteers will have diarrhea for a few days.
Name: ACE527
Name: dmLT
Name: CeraVacx placebo
Name: H10407 challenge strain
Description: Unsolicited adverse events were collected throughout Part A of the study, were graded for severity, and assessed for relationship to vaccine. Withdrawal from the study due to adverse event was determined at the discretion of the study staff.
Measure: Part A: Number of Serious Adverse Events and Adverse Events Leading to Withdrawal Time: up to 1 month after last vaccination (3 months)Description: Unsolicited adverse events were collected throughout Part A of the study, were graded for severity, and assessed for relationship to vaccine. Generally, mild severity is discomfort with no disruption of normal daily activities and relieved with or without symptomatic treatment; moderate severity is discomfort sufficient to reduce or affect normal daily activity somewhat and only partially relieved with symptomatic treatment; and severe is discomfort sufficient to reduce or affect normal daily activity considerably; prevents regular activities, and not relieved with symptomatic treatment. Additional description of severity for diarrhea, body temperature, and vomiting is described in the protocol.
Measure: Part A: Number of Participants Experiencing Unsolicited Adverse Events, by Severity and Relationship to Vaccination Time: up to 1 month after last vaccination (3 months)Description: Solicited reactions were collected 1 week after each vaccination.
Measure: Part A: Number of Solicited Reactions Time: up to 1 week after each vaccination (at 0, 1, and 2 months)Description: Defined as a four-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Antibody in Lymphocyte Supernatant (ALS) Immunoglobulin A (IgA) Response to E. Coli Heat Labile Toxin B Subunit (LTB) Time: Vaccination 1 Day 3 and 7; Vaccination 2 pre-vaccination, Day 3, and Day 7; Vaccination 3 pre-vaccination, Day 7, and Week 4Description: Defined as a four-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Antibody in Lymphocyte Supernatant (ALS) Immunoglobulin A (IgA) Response to Enterotoxigenic Escherichia Coli (ETEC) Colonization Factor 1 (CFA/I) Time: Vaccination 1 Day 3 and 7; Vaccination 2 pre-vaccination, Day 3, and Day 7; Vaccination 3 pre-vaccination, Day 7, and Week 4Description: Defined as a four-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Antibody in Lymphocyte Supernatant (ALS) Immunoglobulin A (IgA) Response to E. Coli Surface Antigen 3 (CS3) Time: Vaccination 1 Day 3 and 7; Vaccination 2 pre-vaccination, Day 3, and Day 7; Vaccination 3 pre-vaccination, Day 7, and Week 4Description: Defined as a four-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Antibody in Lymphocyte Supernatant (ALS) Immunoglobulin A (IgA) Response to E. Coli Surface Antigen 6 (CS6) Time: Vaccination 1 Day 3 and 7; Vaccination 2 pre-vaccination, Day 3, and Day 7; Vaccination 3 pre-vaccination, Day 7, and Week 4Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin A (IgA) Response to E. Coli Heat Labile Toxin B Subunit (LTB) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin A (IgA) Response to Enterotoxigenic Escherichia Coli (ETEC) Colonization Factor 1 (CFA/I) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin A (IgA) Response to E. Coli Surface Antigen 3 (CS3) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin A (IgA) Response to E. Coli Surface Antigen 6 (CS6) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin G (IgG) Response to E. Coli Heat Labile Toxin B Subunit (LTB) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin G (IgG) Response to Enterotoxigenic Escherichia Coli (ETEC) Colonization Factor 1 (CFA/I) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin G (IgG) Response to E. Coli Surface Antigen 3 (CS3) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Defined as a 2.5-fold rise or greater in geometric mean titer.
Measure: Part A: Number and Percentage of Subjects With Positive Serum ELISA Immunoglobulin G (IgG) Response to E. Coli Surface Antigen 6 (CS6) Time: Day 7 post-all vaccinations; pre-vaccination 2 and 3; week 4 post-vaccination 3Description: Severe diarrhea was defined as >800 grams of grade 3-5 stools passed over the 120-hour observation period. For episodes starting at or before 120 hours post-challenge, volunteers were followed to resolution and the total stool output weight was considered in determining whether a specific volunteer met the primary definition of severe diarrhea. The end of a diarrheal episode occurred when a volunteer did not pass any grade 3-5 stool in a 24-hour period. Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Number and Percentage of Subjects Experiencing Severe Diarrhea Following H10407 Challenge Strain Time: 5 daysDescription: Defined as mild, moderate, or severe diarrhea, specifically: Mild diarrhea: 2 or 3grade 3-5 stools totaling 200 g - 400 g, or 1 grade 3-5 stool of >300 g Moderate diarrhea: 4-5 grade 3-5 stools totaling >200 g or 401 - 800g Severe diarrhea: > 800g grade 3-5 stool(s) Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Number and Percentage of Subjects Experiencing Diarrhea of Any Severity Time: 5 daysDescription: Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Mean Total Weight of Grade 3-5 Stools Passed Per Volunteer Time: 5 daysDescription: Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Median Total Weight of Grade 3-5 Stools Passed Per Volunteer Time: 5 daysDescription: Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Mean Number of Grade 3-5 Stools Passed Per Volunteer Time: 5 daysDescription: Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Median Number of Grade 3-5 Stools Passed Per Volunteer Time: 5 daysDescription: Solicited reactions were generally graded as mild if there was discomfort, but no disruption of normal daily activities; moderate if if discomfort was sufficient to affect normal daily activity and partially relieved with symptomatic treatment; severe if discomfort was sufficient to affect normal daily activity considerably, prevent regular activity, and not relieved with symptomatic treatment.
Measure: Part B: Number of Subjects Experiencing Solicited Reactions Graded as Moderate or Severe Time: 1 weekDescription: When asking about adverse events, subjects were asked whether their illness resulting from ETEC would have reduced their daily activity because of their illness if they had been vacationing or traveling on business.
Measure: Part B: Number and Percentage of Subjects Who Would Have Reduced Daily Activity Time: 5 daysDescription: Defined as mild, moderate, or severe diarrhea, specifically: Mild diarrhea: 2 or 3grade 3-5 stools totaling 200 g - 400 g, or 1 grade 3-5 stool of >300 g Moderate diarrhea: 4-5 grade 3-5 stools totaling >200 g or 401 - 800g Severe diarrhea: > 800g grade 3-5 stool(s) Grades were defined as follows: Grade 1: firm, formed (normal) Grade 2: soft, formed (normal) Grade 3: viscous opaque liquid or semi-liquid which assumes the shape of the container Grade 4: watery, non-viscous, opaque liquid which assumes the shape of the container Grade 5: clear or translucent, watery or mucoid liquid which assumes the shape of the container
Measure: Part B: Mean Time to Onset of Diarrhea Among Subjects Who Had Diarrhea Time: 5 daysAllocation: Randomized
Parallel Assignment
There is one SNP
LT(R192G/L211A), or dmLT, is a derivative of wild-type enterotoxigenic Escherichia coli heat-labile enterotoxin that has been genetically modified by replacing the arginine at amino acid position 192 with glycine and the leucine at amino acid position 211 with alanine. --- R192G ---