1. The following picture represents test results from blood samples of two patie
ID: 188098 • Letter: 1
Question
1. The following picture represents test results from blood samples of two patients A and B. Patient A has been vaccinated against influenza virus 12 wecks ago, while B has received the same vaccine 48 hours ago. Both samples were tested for using ELISA. (HA is a protein on the surface of the influenza virus, that helps with attachment.) The same protocol was followed as shown in the video under the protocol section for ELISA presence of antibodies to influenza HA antigen Positive control (HA present) Negative control (HA absent) Sample A Sample B A. What does the presence of blue color indicate? B. Which patient(s) tested positive for presence of influenza HA antibodies? C. What could be a reason for the results for patient B results? (You may need to watch this week's video in MIC205 on vaccination - Lecture 5) to help you answer this question.) D. What does the positive control indicate? Or what information can you gather from the positive control? information can you gather from the negative control? F. As performed, is this a qualitative test or a quantitative G. The results show that each assay was performed 3 times E. What does the negative control indicate? Or what test? (in triplicate). Why do you think this assay was performed in triplicate? H. At this point and time, if A and B would be exposed to influenza virus, who would be better protected? I. Predict what your results would be if your blood wasExplanation / Answer
1.
A) It indicates the presence of antibodies to influenza HA antigen.
ELISA is a molecular technique that uses an enzyme that creates a detectable product (like color) as a reaction to the presence of a specific antibody, in this case the antibody for influenza HA antigen.
B) Sample A tested positive for the antibody, since it´s the one that has the presence of color blue.
C) The reason for sample B's abscence of the antibody could be because it has only been 48 hours since the vaccine. If the patient hasn´t had contact with this influenza virus before then he does not have immunological memory (this is the point of vaccines, they create immunological memory without infecting the body, just by contact with the pathongen's antigen).
Patient B, therefore will create antibody through primary humoral response, which is slow, it has a lag phase of 4-7 days approx and reaches peak of antibody level in about 7 days.
D) The positive control indicates that the ELISA test results are reliable, the reactives work correctly, the enzyme activates correctly at the presence of the antibody.
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