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    Hi, i have some questions about this.

    Firstly, why is the test needed in the first place i.e. why is it needed to see if a patient has a certain antibody for a certain antigen in their blood?

    Secondly, what is the point in washing the well after the blood plasma has been added? I can understand why it would need to be washed after adding the secondary antibodies with an enzyme attached, but why is it important to wash the well after the blood is added?

    Many thanks
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    1) It is used to detect the presence of certain viruses /microbes etc. These microbes have specific antigens so if the antigens are detected from Elisa test, it shows the test sample (e.g blood or urine) has been infected by the microbe.

    2) Washing the well after blood is added is usually done as a precaution, just to remove any components of the blood not neccessary for the Elisa test. The most important washing is after the enzyme-bound -antibody is added, as you stated.
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    (Original post by Bertybassett)
    Hi, i have some questions about this.

    Firstly, why is the test needed in the first place i.e. why is it needed to see if a patient has a certain antibody for a certain antigen in their blood?

    Secondly, what is the point in washing the well after the blood plasma has been added? I can understand why it would need to be washed after adding the secondary antibodies with an enzyme attached, but why is it important to wash the well after the blood is added?

    Many thanks
    Lets take HIV as an example as this is the most common use

    1) - The test is needed to test for HIV antigens in a persons blood plasma, this goes into a solution with HIV antigens bound to the bottom of the well at which these antibodies bind if they're complementary to the antigen in which the person does contain antigens for HIV.

    2) the point in washing the well after the blood plasma has been added is to wash away any unbound antibodies from the well, as if it's not washed then when the enzyme is added this could bind to the antibodies that aren't HIV and produce a false positive test
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    (Original post by Najrul Islam)
    1) It is used to detect the presence of certain viruses /microbes etc. These microbes have specific antigens so if the antigens are detected from Elisa test, it shows the test sample (e.g blood or urine) has been infected by the microbe.

    2) Washing the well after blood is added is usually done as a precaution, just to remove any components of the blood not neccessary for the Elisa test. The most important washing is after the enzyme-bound -antibody is added, as you stated.
    thanks for the reply. What if they put the antigens at the bottom of the well and then add the blood plasma so that the person's antibodies wil bind to these antigens? What is the point in seeing if a person has certain antibodies to a certain antigen in their blood? thanks
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    Not completely sure but it could be to see if the person is protected against a certain pathogen?
    the most useful one is definitely the Direct ELISA test (detecting antigens).
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