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Testing Options

GMO food/feed testing is based on some fundamental principles of genetic engineering and cellular physiology:

  • DNA: The introduction of foreign DNA into a recipient plant’s DNA (genetic engineering)
  • Protein: The information coded in DNA is translated into protein that performs the function specified by the DNA instructions (cellular physiology)

Two methods have been developed based on these fundamentals: genetic analysis (DNA analysis) and Immunological analysis (Protein analysis). Three tests are currently available using these methods.
 
Genetic Analysis (DNA analysis)
 
Genetic analysis is a GMO testing method that detects the presence of a transgene in a plant cell’s genome. The specific GMO test used in this method is called the polymerase chain reaction (PCR) test.
 
Polymerase Chain Reaction (PCR Test):
 
  • Copies a specific section of a plant’s DNA billions of times in order to detect and quantitate foreign DNA (GMO) inserted into the plant’s genome.
  • Uses short pieces of DNA (primers) that are complementary to the GMO sequence to vastly amplify and quantitate GMOs.
  • Performed in a laboratory setting.
  • Appropriate for qualitative or quantitative testing.
  • Highly sensitive and specific.

 


Immuno-analysis (Protein analysis)
 
Immunological analysis, or immuno-analysis for short, is a GMO test method that detects proteins. Currently, there are two types of GMO tests that use this method: the Strip Test and ELISA Method. 
 
Strip test (Lateral Flow Device or Dipstick):

  • A rapid antibody-based method used for measuring GMO protein in unprocessed material such as seed, grain, or leaves
  • Uses a detection surface comprised of immobilized GMO protein-specific antibodies on a solid strip  
  • Appropriate for qualitative or semi-quantitative testing
  • Suitable for field testing

  ELISA Test (Enzyme-Linked Immunosorbent Assay)

  • An antibody-based method for measuring GMO protein in unprocessed material such as seed, grain, or leaves
  • Uses a detection surface comprised of immobilized GMO protein-specific antibodies in a multi-well solid plate format 
  • Appropriate for qualitative or quantitative testing
  • Performed in a laboratory setting

More on Immuno-analysis 


Determining which type of GMO test is most appropriate depends on several factors, including but not limited to: 
  • Nature of the sample
  • GMO(s) to be analyzed
  • Required test sensitivity
  • Whether qualitative or quantitative analysis is required
  • Product’s intended market

The chart below summarizes GMO testing options, including the advantages and disadvantages of each method.
 
GMO testing options  

Analysis Test Measures Advantages Disadvantages
  Immunologic
Strip
test
  
   Protein   Because the test is rapid
  and can be performed on-
  site, this method is very
  useful as an initial screen
  for seed and grain
  Often low sensitivity (Limit of  
  detection 0.1 – 1%)
  Because the test is not
  performed with laboratory
  controls, operator error
  resulting in inaccurate test
  results can sometimes be an
  issue.
  Not appropriate for processed  
  products
  GM protein levels may vary
  between different commercial
  GM cultivars and different parts
  of the same GM plant
ELISA Protein   High sensitivity
  (Limit of detection 0.01 –
  0.1%)
  Not appropriate for processed
  products
  GM protein levels may vary  
  between different commercial
  GM cultivars and different parts
  of the same GM plant
  Must be performed in a
  laboratory
    Genetic PCR DNA   High sensitivity (limit of
  detection 0.01%) and
  specificity
 
  Must be performed in a  
  laboratory
  Capable of detecting all
  GMOs
  Allows definitive  
  quantification

  Effective with broad range
  of sample types

  Industry standard used
  worldwide in surveillance
  and testing labs
 
 

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