Human Challenge Model Refinement With Enterotoxigenic Escherichia Coli Strain B7A

Healthy Volunteer Clinical Trial

Official title: Human Challenge Model Refinement for B7A, An Enterotoxigenic Escherichia Coli (ETEC) Challenge Strain That Expresses CS6

Status Completed

Clinical Trial Summary

The purpose of this study is to determine the safe and optimal dose and regimen (fasting duration) for administering the challenge ETEC strain B7A, a CS6 expressing ETEC strain.

Additionally, an assessment of homologous protection following rechallenge with B7A will be assessed.

Clinical Trial Description

Enterotoxigenic Escherichia coli (ETEC) is the most common causes of infectious diarrhea in children in resource limited countries, and is also a frequent cause of traveler's diarrhea in civilian and military travelers to endemic countries. ETEC strains express one or both of two enterotoxins (heat labile toxin (LT) and heat stable toxin (ST)) that cause help the bacteria cause the main symptom of watery diarrhea. They also express a variety of colonization factors (CF) that help them attach to the intestinal wall. Each colonization factor has one or more surface antigens (CS).

Vaccines and treatments to prevent ETEC disease are under development. Some of these target specific enterotoxins or colonization factors. For over 40 years, we have used ETEC human challenge studies to understand the ETEC disease process, immune response, and more recently, to determine whether treatments or vaccines are protective or effective in mitigating disease. One concern about these challenge study is the use of high doses of bacteria given may overwhelm the protective efficacy of the vaccine or treatment. Several strains of ETEC have been used in these challenge studies; a frequently used strain is B7A (CS6+, LT+, ST+. O148:H28).

This study will explore the optimal dosing strategy for B7A, in order to minimize the dose of ETEC necessary to produce disease in healthy adult volunteers. There will be two inpatient admissions. The first will examine 4 dosing and fasting regimens in healthy volunteers. The second admission will include volunteers who became ill during the first admission, as well as a new group of volunteers. This second admission will validate the optimal dose from the first admission, as well as to determine if previous infection with B7A ETEC will protect against a new infection. Trying to understand the immune response to this challenge organism may help us optimize vaccine design and delivery to protect people from this infection. ;

Related Conditions & MeSH terms

• Healthy Volunteer

• NCT number: NCT02773446
• Study type: Interventional
• Source: Johns Hopkins Bloomberg School of Public Health
• Status: Completed
• Phase: N/A
• Start date: April 2016
• Completion date: December 2016