Recipient Organization
TUFTS UNIVERSITY
200 WESTBORO ROAD
N. GRAFTON,MA 01536
Performing Department
Infectious Disease and Global Health
Non Technical Summary
In humans, Clostridium difficile infection (CDI) can manifest with symptoms ranging from asymptomatic carriage to chronic diarrhea to severe, fatal systemic disease, and the gnotobiotic piglet provides a model which mimics these clinical manifestations. It is not clear whether the administration of specific neutralizing antibodies against TcdA and TcdB are fully, partially or not protective against CDI in the gnotobiotic piglet model. In this study, the impact of administration of specific antitoxin antibodies, given together or separately, on bacterial colonization, mucosal damage, toxin production and cytokine profile will be determined.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
The overall objective is designed to exploit the gnotobiotic piglet model of Clostridium difficile infection (CDI) to assess the ability of the human monoclonal antibodies (Hmabs) against TcdA and TcdB to prevent the recurrence" of CDI, rather than treating an existing infection/disease. To simulate "recurrence" the investigator will treat piglets with Hmabs to determine whether the administered circulating antibodies are capable of preventing infection or disease in animals subsequently challenged with C. difficile. The specific goals of this project are: 1) Establish the effective combined dose of C. difficile anti-TcdA and anti-TcdB human monoclonal antibodies (Hmabs) required to modify, delay, or prevent CDI recurrence after bacterial challenge. 2) Using the dose established in (1), evaluate the therapeutic efficacy and ability to delay, modify or prevent recurrence of CDI with the optimized mixture of Hmabs, as compared with either TcdA or TcdB Hmab given separately in the piglet model of CDI. 3) Assess and compare the clinical and pathological impact of the 3 treatment groups, with a placebo treated group on the gastrointestinal tack and systemically in the piglet model of CDI. 4) Calculate the optimal protective serum concentration of Hmab required to prevent, delay, or modify the outcome of CDI in the piglet model.
Project Methods
The investigator will first establish the optimal Hmab dose required to prevent, delay or modify the occurrence of disease. The investigator will then determine whether the systemic administration of an optimal amount of Hmabs can (and to what extent) prevent or modify the "recurrence" of disease in piglets challenged with C. difficile. Objective 1: Group of piglets will receive a mixture of Hmab. They will be challenged orally with bacterial spores. They will be monitored for clinical symptoms of disease and compared with placebo treated piglets. Objective 2: 24 piglets will be divided into 4 groups of 6. Group 1 will receive a mixture of TcdA and TcdB; Group 2 will receive TcdA; Group 3 will receive TcdB; Group 4 will receive a placebo. All 24 piglets will be orally challenged the next day with spores. Animals will be monitored several times daily for clinical symptoms (diarrhea, anorexia, depression, hunched back, dehydration etc), bacterial shedding and toxin excretion. Objective 3: Animals will be examined for gross pathology, and histological sections from all gut and visceral organs will be examined microscopically by a certified pathologist. Bacterial counts from the small and large intestines will be determined; toxins will be measured in the gut, serum, urine, pericardial plural and peritoneal cavities. Cytokine profile in serum and in gut segments will be measured. Objective 4: Serum will be collected from piglets and the concentration of circulating TcdA and/or TcdB will be calculated, which will help establish the protective dose.