From 2014.igem.org

Background

The following are important concepts for understanding our project:

Agglutination

Agglutination is defined as “the clumping of bacteria, red blood cells, or other cells, due to the introduction of an antibody.”^[1] It is a process used by the body to protect itself from foreign entities. It is driven by the interaction of antibodies and cell surface proteins known as antigens. These antigens are proteins expressed on the surface of foreign agents which are recognized by the body as foreign. The body’s natural defense system, the immune system, creates antibodies which are designed to match these antigens. This is known as acquired immunity. These antibodies have two allosteric sites which can bind to specific antigens. Generally the cells expressing antigens have many antigens covering their surface. This allows multiple antibodies to be bound to multiple antigens creating an array, or network, of antibodies and cells. This is known as coagulation. Visual agglutination tests are currently used for things like blood typing. For this process an unknown blood type is mixed with known antibodies. The unknown blood type will coagulate with the antibodies that match the antigens expressed on their cellular surface which will allow for identification of the blood type.

BclA

BclA is a protein from the bacteria Bacillus anthracis. Within the bacteria, the BclA protein consists of three domains. The first domain is the N-terminal domain, which anchors the protein into the cellular membrane. The next two regions are the collagen-like region (CLR) and the C-terminal domain. The CLR is so named because it is a helical structure which resembles that of collagen fibers and consists of a repeating sequence of amino acids. Within the context of this project only the N-terminal domain is important. Research by Park et. al showed that the NTD of BclA can be linked to other protein domains to express those proteins on the cellular surface. Specifically, the work attached a green fluorescent protein to the NTD of BclA. This construct was transformed into bacterial cells and observed under a microscope to prove that the GFP was localized to the cellular surface, which it was^[2].

CAEV

Goats are one of the most common livestock animals in developing nations. Over 1 billion goats are used as livestock around the world^[3]. Caprine arthritis encephalitis virus (CAEV) is a retrovirus that can infect both goats and sheep. The most common symptoms of the disease include polyarthritis and inflammation of breast tissue (resulting in the inability to produce milk). Cases of CAEV have been reported all around the world in both developing and developed countries^[3]. There is currently no cure or treatment for CAEV. However, once identified, the goats or sheep can be isolated from the herd— a crucial step in preventing infection, considering how quickly CAEV can spread from animal to animal.