Serological Tests Prt2

Question 1

What are the types of antibody label serological assay

Answer 1

Elisa
Immunofluorescence Assay
Lateral flow immuno chromatographic assay

Question 2

What is the ELISA

Answer 2

Used to detect and quantitate antigens are antibodies in a patient’s sample

Question 3

What is the principal of the ELISA

Answer 3

Antigen is immobilized to a solid surface
Done directly or via the use of a capture auntie body itself immobilized on the surface
Antigen is then complexed to a detection antibody conjugated with a molecule amenable for detection such as an enzyme
Enzyme labeled antibody is used
Activity changes color

Question 4

What are the types of ELISA

Answer 4

Direct Elisa
Indirect ELISA
Sandwich Elisa

Question 5

Describe the direct ELISA

Answer 5

Antigen is immobilized to the surface of the multiwell plate and detected with an antibody specific for the antigen
Antibody is directly conjugated to HRP or other detection molecules

Question 6

Indirect ELISA

Answer 6

▪️Technique that uses a two-step process for the function of antigens ▪️primary antibodies specific for the antigen binds to the target
And a labeled secondary antibody against the host species of the primary antibody binds to the primary antibody for the detection
▪️Antigen is immobilized to the surface of a multiwell plate
▪️Method can be used to detect specific antibodies in the serum sample by substituting the sample for the primary antibody

Question 7

Describe the sandwich ELISA

Answer 7

▪️Most common used format
▪️Requires two antibody specific for different epitopes of the antigen
▪️One of the antibodies is coated on the surface of a multi well plate and used as a capture antibody to facilitate the immobilization of the antigen
▪️The other antibody is conjugated with enzyme and facilitates the detection of the antigen

Question 8

What are the advantages versus the disadvantages of the direct ELISA

Answer 8

Advantages:
Short protocol saves time and agents
no cross your activity from secondary antibody
Disadvantages:
No signal amplification
low flexibility:the primary antibody must be conjugated

Question 9

Advantages versus disadvantages of indirect ELISA

Answer 9

Advantages:
Signal amplification several secondary antibodies will bind to the primary antibody
High flexibility:the secondary antibody may be used for several primary antibodies
Disadvantages:
Long protocol compared to direct Elisa
Potential cross-reactivity from secondary antibody

Question 10

Advantages versus disadvantages of the sandwich ELISA

Answer 10

Advantages:
High specificity involves two antibodies detecting different Epitopes on the same antigen
High flexibility and sensitivity: both direct and indirect methods can be used

Disadvantages:
Demanding design:finding two antibodies against the same target that recognize different Epitopes

Question 11

What is the clinical relevance of the ELISA

Answer 11

Hepatitis markers
HIV AB
heliobacter pylori AB

Question 12

What is the immunofluorescence assay

Answer 12

Technique that can detect a range of antigens in different type of tissues of various cell preparations

Question 13

What’s the principle of IFA

Answer 13

IF relies on the use of antibodies to label a specific target antigen with a fluorescent dye such as fluorescein isothiocyanate (FITC) generating florescence against dark background which can be seen under the fluorescent microscope

Question 14

What are the different types of IFA techniques

Answer 14

Direct: uses a single antibody directed against the target of interest the primary antibody is directly conjugated into a fluorophore
Indirect: uses two antibodies the primary antibody is unconjugated and a fluorophore conjugated secondary antibody directed against the primary antibody is used for detection

Question 15

What is the clinical relevance of IFA

Answer 15

Influenza A&B
Cytomegalovirus
Measles
Herpes virus

Question 16

Describe the natural flow immunochromatographic Assay

Answer 16

Technique that uses nitrocellulose paper with colored nano particles and uses antibodies for detection of antigens in complex mixtures where the sample is placed on a test device and the results are displayed within minutes
due to the low development costs in the ease of production they have been widely used in multiple fields in which Rapid test required
also used as point of care testing in many fields

Question 17

What is the principle of lateral flow immunochromatographic assay

Answer 17

▪️A liquid sample containing the antigen of interest flows by capillary action through various zones of polymeric strip on which antibodies can interact with the analyte attached
▪️Two types of antibodies are found one specific to the antigen and the other is anti-IgG(control)
▪️Their role is to react with the target antigen bound to the conjugated antibody generating a color
▪️The presence of the target antigen results in the appearance of color on the test line while Color on the control line indicates the proper liquid flow through the strip

Question 18

What is the clinical relevance of immunochromographgraphic assay

Answer 18

COVID-19
group a streptococcus
rotavirus