Final answer:
A bacterin is a vaccine prepared from killed bacteria, used to stimulate the body's immune response without causing the disease. It involves the introduction of bacterial antigens to produce antibodies and promote adaptive immunity.
Step-by-step explanation:
A bacterin is defined as (c) vaccine prepared from a killed bacteria. Bacterins are used to elicit an immune response in the body without causing the disease. A vaccine does this by introducing antigens specific to a pathogen into the body, which then provoke the production of antibodies and a cell-mediated immune response by the body's immune system. In the case of a bacterin, the antigens come from bacteria that have been inactivated or killed so that they cannot cause infection.
The process involves the antigens being taken up by antigen-presenting cells which display them on their surface. This in turn leads to the stimulation of B lymphocytes, which then produce antibodies. These antibodies, alongside memory cells, help to protect the individual against future infections by the same pathogen.