The agar gel immunodiffusion (AGID) test is
used to detect antibodies to Type A influenza group-specific antigens
, i.e., the ribonucleoprotein (RNP) and matrix (M) proteins. Therefore, this test will detect antibodies to all influenza A virus subtypes.
What is gel diffusion test?
In the gel double-diffusion test (Ouchterlony test),
the virus-antibody reaction takes place in agar gel
. Virus and antiserum are placed in opposite wells in an agar plate. Virus particles and antibodies then diffuse into the agar.
What does agid mean on a Coggins test?
Agar gel immunodiffusion
(AGID). Also known as the Coggins test, AGID is the most widely accepted procedure for the diagnosis of EIA. The test detects antibody against the viral p26 antigen (major core protein). It is the only procedure that has been statistically correlated with the presence of EIA virus in blood.
What happens during an immunodiffusion test?
Immunodiffusion is a diagnostic test which involves
diffusion through a substance such as agar
which is generally soft gel agar (2%) or agarose (2%), used for the detection of antibodies or antigen.
How does an immunodiffusion assay work?
The basis for the immunodiffusion test is
concurrent migration of antigen and antibody towards each other through an agar or agarose gel
. As the antigen and antibody come in contact, they combine to form a precipitate that is trapped in the gel matrix and produces a visible line.
What happens if you get a positive Coggins test?
Due to this fact, horses testing positive
must be euthanized or under strict lifelong quarantine
. Equine Infectious Anemia virus reproduces in white blood cells that circulate throughout the body. A horse’s immune system may attack and destroy red blood cells leading to anemia.
Is Coggins curable?
The Coggins Test is the diagnostic tool for Equine Infectious Anemia (EIA), a disease with
no vaccine or cure
.
How many types of Immunodiffusion are there?
Simple immunodiffusion (Oudin technique) in which one of the
two
reagents remains fixed (either the antigen or the antibody) and the other reagent moves. Double immunodiffusion (Ouchterlony technique) in which antigen and antibody arefree to move towards each other.
How does an AGID test work?
A diagnostic test using serum (the fluid, non-cellular part of blood) that
detects antibody produced in response to infection
. Serum is placed in a well in the agar and a MAP antigen preparation is placed in a nearby well.
Why CFT test is done?
The complement fixation test (CFT) is a classical laboratory diagnostic test, which is still
used for determination of virus antibodies in patient sera or cerebrospinal fluid samples during an acute infection
. The test mainly measures IgG antibodies.
What is the main principle of immunodiffusion?
PRINCIPLE: Immunodiffusion in gels encompasses a variety of techniques, which are useful for the
analysis of antigens and antibodies
. An antigen reacts with a specific antibody to form an antigen-antibody complex, the composition of which depends on the nature, concentration and proportion of the initial reactants.
What is antiserum used for?
Antiserum is human or nonhuman blood serum containing monoclonal or polyclonal antibodies that is used
to spread passive immunity to many diseases via blood donation
(plasmapheresis).
What is hemagglutination reaction?
Hemagglutination is a
reaction that causes clumping of red blood cells in presence of some enveloped viruses
, such as the influenza virus. A glycoprotein on the viral surface, namely hemagglutinin, interacts with red blood cells, leading to the clumping of red blood cells and the formation of a lattice.
What is the purpose of immunodiffusion?
Immunodiffusion or enzyme immunoassay (EIA) is
used serologically to measure IgM and IgG antibodies
.
Is a hapten and immunogen?
We can define an
immunogen
as a complete antigen which is composed of the macromolecular carrier and epitopes (determinants) that can induce immune response. An explicit example is a hapten. Haptens are low-molecular-weight compounds that may be bound by antibodies, but cannot elicit an immune response.
What are immunodiffusion tests used for?
Immunodiffusion is one of the methods used to
diagnose fungal diseases
. Complement fixation is also used to test for some of the fungal diseases. The specific type of immunodiffusion is called Double (Ouchterlony) microimmunodiffusion. The procedure involves adding antigen and antibody to wells in an agarose gel.
