Module 05 Flashcards
What does ELISA stand for?
Enzyme-linked immunosorbent assay
What is ELISA used for in health care?
Broadly-applicable technique which can be modified to detect and quantify substances such as peptides, proteins, antibodies, hormones, and other molecules
How does ELISA work? (4 steps)
1- Bottom of wells are coated with an antigen that is specifically recognized by the antibody you wish to measure
WASH -remove excess antigen
2- Sample containing antibody to be measure is added to the well. Primary antibodies, if present, will bind to the antigens atteched to the bottom of the well
WASH - remove excess primary antibody not attached to antigen
3- Enzyme-conjugated secondary antibody is added to the well. This will bind to the Fc Portion of the primary antibodies already present in the well - specific to animal
WASH - remove excess secondary antibody
4- Substrate of the enzyme attached to the secondary antibody is added to the well. Reaction of the substrate and the enzyme produces a coloured product which can be measure by absorbance
What does ELISA measure?
Coloured reaction product buy absorbance by a spectrophotometric plate reader.
Data measured correlates with the presence of an antibody or an antigen
– USed to detect presence of viral disease
What is an indirect ELISA?
Detects/Quantifies antibody
What is the difference between Detection and Quantification
Detection: IF substance is present or absent
Quantification: evaluates the concentration of substance
How can flow cytometry be used in the diagnosis of HIV/AIDS?
Diagnosis of AIDS is made based upong the number of CD4+ T-cells found in a patient’s serum. Flow cytometry can be used to identify and count these specific T-cells in a blood sample
What does flow cytometry measure?
Physical properties of a cell eg specific antigen on or inside a cell
What detection tool is used in CBC (complete blood counts)?
Flow cytometry
How does flow cytometry work?
1- Narrow stream of cells in single file is passed through a laser light source – each cell uniquely scatter laser light
- Forward and Side scattered light is measured which helps in the discrimination by cell size
What is a clinical application of flow cytometry?
Diagnosis of cancer
What is the advantage of using monoclonal antibodies in contrast to polyclonal antibodies?
Monoclonal antibodies are a homogenous population of antibodies with exquisite specificity for a single antigen whereas polyclonals could recognize multiple antigens
What does Monoclonal antibodies measure?
It is not a specific technique of measurement - tool useful in many applications
What are the 2 types of monoclonal antibodies?
1- immunotoxins
2- Radiolabelled antibodies
What is immunotoxins and what is it used for?
Tumour-specific monoclonal antibody attached to a deadly toxin.
This technique is still under investigation but shows promise in targeting and eliminating tumour cells and treat cancer
What is Radiolabelled antibodies and what is it used for?
Monoclonal antibodies tagged with a radioactive isotope. Can bind to antigens on a tumour thereby allowing precise location
Can be used for the diagnosis of tumour earlier than other methods.
How does Monoclonal Antibodies work
Monoclonal antibodies are produced in the laboratory by hybridomas, immortal cells that produce unlimited qties of one identical antibody
Hybridomas are the results of fusion between a plasma cell and a cancerous cell. - share properties of both types
Who developed Monoclonal antibodies?
George Kohler and César Milan
What are 2 clinical application of monoclonal antibodies?
Defence against specific diseases and even cancer
Why are vaccines preventative in protecting against infection?
Vaccines are made up of fragments/entire pathogen that is modified (killed or attenuated) allowing immunological response to develop without contracting the disease. This results in immunological memory
What are the 4 types of vaccines?
- Live-attenuated
- Killed-Inactivated
- Toxoid
- Subunit
What are live attenuated vaccines?
Contains a modified strain of the disease-causing agent which has lost its pathogenic ability, but retains its capacity to replicate within the hose
What are the advatange (1) and disadvantages (2) of live attenuated vaccines?
Ad:
Provides a prolonged exposure to the pathogen and is suitable to generate cell-mediated immunity
Dis:
- Potential to revert to a virulent form
- Requires specific storage and transport conditions (refrigeration)
Small pox vaccine, oral poliovirus vaccine and measles vaccine are example of which type of vaccine?
Live attenuated
Give 3 examples of live-attenuated vaccines?
Smallpox vaccine
Oral poliovirus vaccine
Measles vaccine
What are killed-inactivated vaccines?
Contains a strain of the pathogen that has been inactivated by heat, chemical or radiation. It has the ability to generate an immune response but unable to replicate
What are the advantages (2) and disadvantages (2) of killed-attenuated vaccine?
Ad:
- Safer Option as it cannot mutate back to virulent form
- Easy to store and transport
Dis:
-Generally requires multiple booster doses to maintain immunity
- Generally must be administered by injection
Rabies vaccine and flu vaccine are examples of what type of vaccine?
Killed-attenuated
Give 2 examples of killed attenuated vaccines?
Rabies, Flu
What are toxoid vaccines?
Contain an inactivated toxin which is a product from the pathogen
What are the advantages (2) and disadvantage (1) of toxoid vaccines?
Ad:
- Safe as it is not a living organism that can divide, spread and/or revert
- Stable as they are less susceptible to changes in temp, humidity and light
Dis:
- May require several doses and usually need an adjuvant
What is an adjuvant?
A substance that enhances the body’s immune response to an antigen
Tetanus vaccine and diptheria vaccine are examples of what type of vaccine?
Toxoid