Clostridium Difficile Studies

Clostridium difficile as a gram positive, spore like bacteria mainly in hospital and widely spread in the community. It causes infection in human intestines such as diarrhea and pseudomembranous colitis. Clostridium difficile original is necessary in human body which helps maintain gastrointestinal balance and body normal regulation. However, overproduction of Clostridium difficile causes Clostridium difficile infections (CDI), overgrowth of bacteria become spore form leading to release two exotoxins toxin A (TcdA) and toxin B (TcdB) which contribute to thousands of deaths. CDI mainly occurs in patients with weakened immune system, such as patient over the age of 65 or patient undergo broad-spectrum antibiotics which disrupts gastrointestinal
Because of number of annual death, unknown mechanism and route of disease, poor treatment of CDI, the CDC has labeled Clostridium difficile as one of three microorganism that pose as “an immediate public health threat and that require urgent and aggressive action”.

In this preliminary paper, TcdA and TcdB are the toxin primarily contribute to Clostridium difficile infection. Two monoclonal antibodies actoxumab and bezlotoxumab are specific for TcdA and TcdB. They found that the two exotoxins TcdA and TcdB bind to host colonocytes of unknown cell surface receptors via their C-terminal combined repetitive oligopeptide (CROP) domain. In order to determine the mechanism of action of actoxumab and bezlotoxumab, they fragmented CROP domain into four parts to determine the interaction between bezlotoxumab and each fragment on CROP domain. By using the X-ray crystallography to
However, they also proposed that the actoxumab and bezlotoxumab combination give a positive effect on neutralizing antitoxin antibodies and reduce CDI symptoms and recurrence rate. We know actoxumab and bezlotoxumab are specific treat TcdA and TcdB toxin for C. difficile infection. Which fragment of CROP domain will actoxumab and bezlotocumab combination bind to, and what is the affinity of each binding site? I’m interested in the mechanism of actoxumab and bezlotoxumab combination antibodies target in Vero cell and then we can make it into vaccine and test on human host cell. Find out the recurrence rate, and whether it will occur resistance. In my Co-op experience, I cloned and purified the 4 fragments of TcdB CROP domain for producing vaccine. The vaccine we made is for TcdB toxin for