IMMUNOASSAY

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IMMUNOASSAY
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Name The Antigen
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Antibody stucture
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Antibody-based methods

• Antibodies can be used to detect pathogens and
  spoilage organisms such as viruses, bacteria and
  moulds, but also low molecular weight food
  contaminants.
• The specificity of an immunoassay is largely
  determined by the intrinsic specificity of the
  antibody used for detection.
• There are three different types of antibodies
  available for assay development polyclonal
  antibodies, monoclonal antibodies and recombinant
  antibodies.

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Polyclonal and monoclonal antibodies

• Used for research and clinical applications.
• hybridoma technology provides reproducible,
  diagnostic, and research purposes.

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Monoclonal Polyclonal
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The method of Monocloonal
Myeloma cells
Antigen
Fuse cells to make hybridomas
Y
Y
Y
Y
Y
Y
Y
Y
Y
Antibody-producing B cells isolated From spleen
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The method of Monocloonal
Clone individual hybridomas in microtiter plates
Grow cells in in vitro culture system
Test colanes for desired antibody
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The method of Monocloonal
Perpetuate as either
Cell culture
Sneak hybridoma tomor
Y
Y
Y
Monoclonal antibodies
Y
Y
Y
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What are monoclonal antibodies and what is the
purpose of them?

• In addition to gene probes scientists are using
  "monoclonal antibodies" to develop food safety
  tests. Antibodies are proteins that the body
  produces to tag foreign invaders
• Monoclonal antibodies are identical antibodies
  produced in large quantities under laboratory
  conditions.
• When they are applied to food samples the
  antibodies can be used to mark and identify
  harmful microbes and toxins.

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THE METHOD OF POLYCLONAL
Polyclonal antiboies (Y) bind themselves to
inveders and eliminate them.
Y
Y
Y
Y
Y
DISEASER INVADER
Y
Y
Y
Y
Y
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THE METHOD OF POLYCLONAL
Y
Y
DISEASED INVACDER DISAPPEAR
Y
Y
Y

Y
Y
Y
Y
Y
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The birth of immunoassay

• Rosalyn Yalow (1921-) and Solomon Berson
  described the first radioimmunoassay in 1957.

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Radioisotope labels

• Disadvantages
• Toxicity
• Shelf life
• Disposal costs

• Advantages
• Flexibility
• Sensitivity
• Size

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Enzyme labels

• Disadvantages
• Lability
• Size
• Heterogeneity

• Advantages
• Diversity
• Amplification
• Versatility

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Fluorescent labels

• Disadvantages
• Hardware
• Limited selection
• Background

• Advantages
• Size
• Specificity
• Sensitivity

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Chemiluminescent labels

• Advantages
• Size
• Sensitivity
• S/N

• Disadvantages
• Hardware

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ELISA

• The ELISA technique is used widely to detect
  and quantitate organisms and/or their products in
  foods, and synopses of some of these applications
  are presented below. For more details, the cited
  references should be consulted.

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Enzyme-linked immunosorbent assay
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ELISA (variation 1)
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ELISA (variation 2)
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Automated heterogeneous immunoassays

• The ELISA can be automated
• The separation step is key in the design of
  automated heterogeneous immunoassays
• Approaches to automated separation
• immobilized antibodies
• capture/filtration
• magnetic separation

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Group Members

• Ms. Monthida J. ID 451-2477
• Ms. Soontharin S. ID 451-4747

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THANK YOU