- Primary serological tests: (Marker techniques) e.g. Enzyme linked immuonosorbent assay (ELISA)
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Transcript of - Primary serological tests: (Marker techniques) e.g. Enzyme linked immuonosorbent assay (ELISA)
- Primary serological tests: (Marker techniques) e.g.
Enzyme linked immuonosorbent assay (ELISA)Immuno flurescent antibody technique (IFAT)Radio immuno assay (RIA)
- Secondary serological tests: e.g.
Agglutination testsComplement fixation tests (CFT)Precipitation testsSerum neutralization tests (SNT)Toxin-antitoxin test
Classification of antigen-antibody interactions:
-Antigens are whole cells (eg. RBC or bacteria).
-Antibodies cross-link the antigens.
-Types of tests:
-Rapid plasma test (syphilis). -Cold agglutinin test (mycoplasma).
-Weil-Felix test (rickettsial). -Latex agglutination test (pregnancy).
Agglutination:
-Agglutination reactions involve whole cell antigens, while precipitation reactions involve soluble antigens.
-Cellular/molecular view of agglutination and
Precipitation reactions that produce visible Ag-Ab complexes.
Agglutination : ( continued )
Agglutination : ( continued )
-The rapid plasma reagin (RPR) test is available as a kit .The patient's serum is mixed with cardiolipin on a plastic-coated card
that can be examined with the naked eye.
Rapid plasma reagin ( RPR test )
Precipitation
-Soluble antigens. -Binding of antibody to antigen, makes the complex insoluble or visible.
-Types of test:
-Tube precipitation . -Ouchterlony (double diffusion).
-Immunoelectrophoresis.
Precipitation : ( Continued )
-Precipitation reactions
Precipitation : ( Continued )
Ouchterlony (double diffusion)
Precipitation : ( Continued )
Precipitation curve :
Complement fixation
-Antibody (lysin), antigen, complement, and sensitized sheep rbc are required.
-Complement is fixed to a Ab-Ag-complex.
-Fixed complement cannot participate in rbc lysis positive reaction or identification .
Complement fixation test
Nephelometry ( Turbidimetry )
- Nephelometry is a technique used in immunology to determine levels of IgM, IgG, and IgA.
Immunofluorescence
-A monoclonal antibody labeled with a fluorescent dye:
-Direct testing. -Indirect testing.
-An example of direct and indirect immunofluorescence testing.
Immunofluorescence testing
Common assays
-Radioimmunoassay (RIA).
-Enzyme-Linked Immunosorbent Assay (ELISA).
Radioimmunoassay (RIA)
-Antibody or antigen is labeled.
-Detect corresponding antibody or antigen.
-Competition between unlabeled and labeled molecule.
Radioimmunoassay (RIA) : ( Continued )
Enzyme-Linked Immunosorbent Assay (ELISA)
-Safer & less costly than RIAs.
-ELISA methods can detect any infectious disease provided if we have antibodies and antigen to any infection, enzyme or any substance.
Enzyme-Linked Immunosorbent Assay (ELISA)
-Horseradish peroxidase or alkaline phosphatase.
-Enzyme releases dye (chromogen).
-Types of test: -Indirect ( Non-competitive ).
-Capture or Sandwich. -Competitive ELISA.
Ex: detecting the presence of serum AbsAbs against HIV
An example of the indirect ELISA method
An example of the capture ELISA method
An example on competitive ELISA method