A. Rapid evolution of the viral antigen
Clarify Question
· What is the key concept addressed by the question?
o This question addresses immunoassays.
· What type of thinking is required?
o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
Gather Content
· What do you already know about immunoassays?
o Immunoassays can rapidly diagnose viral infections. They are tests that allow the detection of a molecule through the use of an antibody.
o Biotechnology companies can make antibodies against a range of viruses and bacteria. These antibodies can be used in immunoassays to detect whether there is virus in a sample collected from a patient. An antibody against a specific virus can be coated into a plastic well on a microtiter plate. When an unknown sample is added to the well, if the virus is present, it will be bound by the antibody. Bound virus can be detected using a second antibody against the virus that has been linked to a fluorescent molecule, or an enzyme that produces a colored product from a suitable substrate. The amount of fluorescence or colored product made by the enzyme, is proportional to the amount of virus present.
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o The antibody is part of the test; the antigen is made by the virus.
o The best explanation for failure of the immunoassay is that the detected antigen has changed, so it is no longer recognizable by the antibody in the test.
o The antibodies in an immunoassay can recognize the proteins on the outside of a virus coat, but they cannot recognize features of the viral DNA itself.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
o Did you recognize that immunoassays rely upon the ability of the antibody to recognize a certain viral antigen protein?