A direct fluorescent antibody test involves the removal of a brain from an individual. Impression smears are then made from the hippocampus, the medulla, and the cerebellum. The smears are put onto microscope slides and then fixed in acetone, which keeps the smear attached to the slide and permeable to FAT reagent. Next an immunoglobulin G conjugated to fluorescein-isothiocyanate is added to the smeared slide. It is then washed and put under a fluorescent microscope. If there is fluorescence, the test is positive.
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IHC is a technique in which proteins of cells, bacteria, or viruses are identified using monoclonal or polyclonal antibodies. The process starts with the dissection and fixation of a particular tissue in formalin. The fixed tissue is then imbedded in paraffin wax. The piece of tissue is then cut into very thin sections and placed onto a slide. The slide is then stained with a variety of stains. Finally, the slide is exposed to antibodies for a certain antigen (monoclonal) or a number of antigens (polyclonal). If the antigen is present, the antibodies will bind making an antibody-antigen complex. If the antibody-antigen complex is not visible, another antibody with an attached enzyme can be added to make the first antigen-antibody complex. A substrate is then added to the slide which requires the enzyme on the antibody to become coloured and thus make the antigen visible under the microscope.
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An ELISA is a process used to detect antibodies or antigens. The process involves two antibody types. The first type will bind to the antigen or antibody of interest and cause an antigen-antibody or antibody-antibody complex. The second type, which is enzyme linked, will bind to the antigen-antibody or antibody-antibody complex. It is a colour producing interaction, and thus colour will indicate a positive complex. Quantification can also be tested, through introducing various dilutions of the antigen or antibody.
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Polymerase Chain Reaction is a test that amplifies small amounts of DNA, by enzymatically replicating a piece of DNA many times. The following diagram explains the process.
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