Q&A Essay Example | Topics and Well Written Essays - 1000 words

Q&A - Essay Example It is an efficient and usually an extremely effective way to test for certain antibodies. The indirect ELISA approach is typically applied in medical testing because it looks for antibodies present in a given sample. Samples are taken from an individual and then these are tested for the presence of antibodies. This helps to determine if the individual’s body is already producing antibodies against certain antigens. After the sample is taken, antigens are introduced. If antibodies are present, they will form a bond that is invisible to the naked eye. An immunuoglobulin is added to the sample in order to verify if a bond was formed or not. The bond between the antibody, antigen and immunuoglobulin will remain on the plate after rinsing. The immunuoglobulin added must be of the same species. Finally, a colour indicator is added so that the bond between the antibody and antigen are identified properly. The accuracy of an ELISA test does rely on certain factors. If these factors ar e in any way compromised or overlooked, the ELISA test results may be unreliable. These factors may also contribute to a false positive or a false negative. The design of an ELISA test may sometimes affect its outcome, and an ELISA test is either direct or indirect. When using the single antibody approach, the laboratory must used a specific, enzyme-labelled reagent. The assay sensitivity affects both the direct and indirect ELISA tests because it measures the amount of accurate positives that are found. There are four types of sensitivities possible in an ELISA test: true positives, false positives, true negatives and false negatives. Whether or not a patient receives a false positive or a false negative is dependent upon how accurately the ELISA test was conducted, and whether a variable important to the outcome were compromised in some way. A false positive indicates that a person who does not in fact carry the antibodies against a specific type of antigen is tested as positive f or those antibodies. Similarly, a false negative indicates that a person who does in fact carry those antibodies against a specific type of antigen, tests negative for them. This may or may not occur with an HIV-1 test if the standard protocol for the ELISA test is correctly or incorrectly followed. Unquestionably, it is of the utmost importance to follow standard ELISA test protocol. ELISA test errors may occur when the reagents used are mishandled or if their integrity is comprised in some way. The reagents for specific antigen tests are usually specific- they may not be interchangeable between different species. Additionally, certain antibodies require certain reagents in order to be effectively read; substitutions cannot be made. Temperature, preparation, preservation, and shelf-life of the reagent affects how its performance. Commercial availability limits the use of some reagents, and therefore the potential for testing for specific antigens. The handling of samples and the re agents used are extremely important to the outcome of the test. Checking expiration dates and properly storing reagents according to their individual requirements is imperative. Reagents must also be checked for signs of disintegration prior to their usage in an assay; examples include precipitation and discoloration. The substrates should always be colourless. The plates where the experiment is conducted must be properly handled. The plates must be large enough to