Question

A college student has been called into the student health office because she tested positive for HIV on the enzyme-linked immunosorbent assay (ELISA). The student asks, "What is this Western blot assay going to tell you?" The best response by the health care provider is:_______________.

Answer 1

Answer: For detection and confirmation of HIV antibodies in blood samples.

Explanation: As the name implies ELISA( Enzyme-linked immunosorbent assay) is the first test widely used for determining the presence of HIV in a person's serum because of its high sensitivity. In an ELISA, a person's serum is diluted 400 times and applied to a plate to which HIV antigens are attached. If antibodies to HIV are present in the serum, they may bind to these HIV antigens. The plate is then washed to remove all other components of the serum. A specially prepared "secondary antibody" (an antibody that binds to other antibodies) is then applied to the plate, followed by another wash. This secondary antibody is chemically linked in advance to an enzyme.

Thus, the plate will contain enzyme in proportion to the amount of secondary antibody bound to the plate. A substrate for the enzyme is applied, and catalysis by the enzyme leads to a change in color or fluorescence. ELISA results are reported as a number; the most controversial aspect of this test is determining the "cut-off" point between a positive and a negative result. A cut-off point may be determined by comparing it with a known standard. Unknown samples that generate a stronger signal than the known or control sample or are called "positive" while those that generate weaker signal are "negative".

Answer 2

Answer:

Answer:

- Basically the western blot assay is an  assay that targeted the  presence of a specific antibodies to a specific antigen.

Explanation:

The western blot assay is a technique which makes use of its specific characteristics of proteins   to analyse  and identify  a particular protein in mixture of different protein extracts.

    it analysis depends

→on the  molecular sizes of the protein under investigation.

→on the transfer to a solid support, and

→Tracing and marking   of protein under investigation by  visualisation of  corresponding synthetic antibodies which bind with antigen.

The procedure involves  denaturation of protein to breakdown the  3-dimensional proteins structure,, which leads to loss of  forms and  inability to interfere with the analytic process.

This is followed by separation of the proteins into their sizes and therefore forms by  Gel Electrophoresis .Specific primary antibody  to bind with the specific antigen is designed. The electrophoresis is washed in a solution which contains  antibody solution,and the results  is transferred to a membrane, with which gives band for each specific protein.

Secondary antibody is introduced into this solution  to bind with the primary antibody( the unbound antibody),and its tracing is detected to determine the   intended protein. This tracing should  appear as single band of antibody-antigen complex.Since an antibody must bind with a specific protein it was designed for.

Explanation: