Mr. Jonathan Payne – Positive and Negative Controls
Positive and Negative Controls
Why are there a number of washing steps in serological tests?
Washing in serological tests is important to wash off excessive antibodies and prevent nonspecific binding of antibodies and antigens.
Describe how you would know that you had a “false positive” result. What does this mean for the rest of your results?
A positive result with negative control will show a false positive which will result in invalidation of all other results.
Describe how you would know that you had a “false negative” result. What does this mean for the rest of your results?
A negative results with a positive control will show a false negative which will result in invalidation of all other results
Direct Fluorescent Antibody Technique
Why is this technique a direct method?
It is direct method because antibodies in this technique have fluorescent dye.
What is an elementary body?
It is an infectious cell type or particle of many several microorganisms.
How do elementary bodies look under the fluorescent microscope?
Various shapes, red color, some also have green patches. It also shows some darker spots in them as well
What do you think would happen if you did not fix the sample to the slide with 95% ethyl alcohol?
Ethyl Alcohol fixes the sample and prevents samples from being washed off and if not used the sample will simply wash off.
Which patient(s) tested positive for Chlamydia?
Patient 2 with 16 green elementary bodies and patient 4 who has 20 green elementary bodies.
Was there any nonspecific binding for any of the samples? Explain.
It looks like patient 3 had 1 elementary body which had green color out of 26 bodies, so yes there nonspecific binding.
Ouchterlony Technique
What is a precipitin line?
When antigen and antibody are in optimal proportion, cross linking of the antigen and antibodies occurs, resulting in forming an insoluble precipitate which is known as Precipitin line.
What is the unknown antigen in the simulation?
I believe the unknown