are a type of protein. The body's immune system produces antibodies when it detects harmful substances, called antigens. Examples of antigens include microorganisms (such as bacteria, fungi, parasites, and viruses) and chemicals.

is any substance that causes your immune system to produce antibodies against it. An antigen may be a foreign substance from the environment such as chemicals, bacteria, viruses, or pollen. An antigen may also be formed within the body, as with bacterial toxins or tissue cells

within a clinical trial, hiding the knowledge of a particular treatment. The three types of blinding are the following: observer-blind—when the researcher does not know the particular treatment that a patient undergoes; single-blind, when only the patient does not know to which group he or she belongs; and double-blind, when both the patient and th [..]

is giving the investigational agent or placebo to the subject and then subsequently challenging the subject with the bacteria that the treatment is designed to prevent.

is the investigational agent that is given to the subject to solicit an antibody response

 A clinical trial is a research study to answer specific questions about vaccines or new therapies or new ways of using known treatments. Clinical trials (also called medical research and research studies) are used to determine whether new drugs or treatments are both safe and effective    

is a disease the causative agents of which may pass or be carried from one person to another directly or indirectly.

is the execessive and frequent evacuation of watery feces.

is a general term for a group of gastrointestinal disorders characterized by inflammation of the intestines, particularly the colon.

is the power or capacity to produce a desired effect; effectiveness