Question

Question 5 1 pts You're carrying out an ELISA test for HIV. During a wash step, the protocol calls for a 30 minute shaking rinse but you forget to take the plate off the shaker until the next morning. What is(are) the most likely outcome(s)? Negative control tests positive Better results because the plate has been washed thoroughly Uninfected patient tests positive for HIV Infected patient tests negative for HIV

Answer 1

Option 4 is correct.

The ELISA test is used to detect the HIV antibody. It checks for some proteins that the body makes in response to HIV.If the blood contains antibodies to HIV, it will bind with the antigen and cause the cassette's contents to change color.

During an ELISA, an unknown amount of antigen is immobilized to the surface of a microplate well and an enzyme-linked antibody is subsequently bound. Between each step, the plate needs to be washed with a solution to remove any non-specific background, such as that caused by unbound proteins or antibodies.

A key step in the ELISA protocol is the wash steps. Washing steps are critical in order to reduce background signal, which can be due to unbound, conjugated antibody resulting in the increase in ratio of signal to noise; but too much of the washing can risk you from stripping specifically bound molecules.

Therefore if the washing follows for overnight instead of 30 minutes,the chances most probably are that the antigen and antibody complex will be disturbed hence the antigen or antibody used for detection of HIV cannot be detected.Hence a positive HIV patient can be tested negative.