Case Study: Applied Genetic Modification

Select a Plant Delivery System
Begin developing the edible hepatitis B vaccine by selecting a plant delivery system. Many plants have been successfully genetically modified, but, for this project, we need to consider how the plant containing the vaccine protein will be cultivated and how the vaccine will be administered.

Using the criteria listed below, choose between four candidate plants: tomato, banana, potato, or alfalfa.

INSTRUCTIONS:
Read the considerations for choosing a plant to produce an edible vaccine and background information about each plant below. Then select a plant for delivering the hepatitis B edible vaccine by clicking on it.


Graphic: Plant Icons
Considerations for choosing a plant to produce an edible vaccine:
  1. The plant should be eaten raw. Cooking may denature the vaccine protein, causing loss of immunogenic structure.
  2. The edible part of the plant should have a reasonably high protein content. A viral protein will be used as the vaccine, since the proteins are the most antigenic, or immune-stimulating, biomolecules.
  3. The plant should be propagated clonally to reduce the risk of outcrossing with non-modified crops.
  4. The plant must have established transformation methods; that is, techniques should be available for transferring a foreign gene into the plant.
  5. The plant should be abundant, inexpensive to produce, and cultivated year-round.
  6. Ideally, the plant the will be cultivated within the vaccination region, such as in developing countries.


       

Select a of the plants to use:
arrow Tomato: Edible raw, although acidic fruit may be incompatible with some antigens or for delivery to infants. Outcrosses in the field, but can be grown in industrial greenhouses. Efficient transformation system is available.

arrow Banana: Fruit is eaten raw by infants and adults. Clonally propagated, with low potential for outcrossing in the field. Transformation methods are relatively inefficient. Abundant and inexpensive fruit is available on a 10–12 month cycle. High space requirement but is cultivated widely in developing countries.

arrow Potato: Unpalatable in the raw form and cooking may cause denaturation and poor immunogenicity of vaccines. Relatively low protein content in tubers. Clonally propagated with low potential for outcrossing in the field. Efficient transformation system.

arrow Alfalfa: Leaves are edible uncooked and have a high protein content. Potential for outcrossing in the field. Relatively efficient transformation system. Deep root system is problematic for clearing fields for growth.