Oral vaccines have been in the works for many years as a possible solution to the spread of disease in underdeveloped countries, where costs are prohibitive to widespread vaccination. Genetically engineered crops, usually fruits or vegetables, designed to carry antigenic proteins from infectious pathogens, that will trigger an immune response when injested. An example of this is a patient- specific vaccine for treating cancer. An anti-lymphoma vaccine has been made using tobacco plants carrying RNA from cloned malignant B-cells. The resulting protein is then used to vaccinate the patient and boost their immune system against the cancer. Tailor-made vaccines for cancer treatment have shown
considerable promise in preliminary studies.
Plants are used to produce antibiotics for both human and animal use. Expressing antibiotic proteins in livestock feed, fed directly to animals, is less costly than traditional antibiotic production, but this practice raises many bioethics issues, because the result is widespread, possibly unneccessary use of antibiotics which may promote growth of antibiotic-resistant bacterial strains. Several advantages to using plants to produce antibiotics for humans are reduced costs due to the larger amount of product that can be produced from plants versus a fermentation unit, ease of
purification, and reduced risk of contamination compared to that
of using mammalian cells and culture media.
The agricultural industry plays a large role in the biofuels industry, providing the feedstocks for fermentation and refining of bio-oil, bio-diesel and bio-ethanol. Genetic engineering and enzyme optimization techniques are being used to develop better quality feedstocks for more efficient conversion and higher BTU outputs of the resulting fuel products. High-yielding, energy-dense crops can minimize relative costs associated with harvesting and transportation (per unit of energy derived), resulting in higher value fuel products.
Plant and Animal Breeding
Enhancing plant and animal traits by traditional methods like cross-pollination, grafting, and cross-breeding is time-consuming. Biotech advances allow for specific changes to be made quickly, on a molecular level through over-expression or deletion of genes, or the introduction of foreign genes. The latter is possible using gene expression control mechanisms such as specific gene promoters and transcription factors. Methods like marker-assisted selection improve the efficiency of "directed" animal breeding, without the controversy normally associated with GMOs. Gene cloning methods must also address species differences in the genetic code, the presence or absence of introns and post-translational modifications such as methylation.
Pest Resistant Crops
For years, the microbe Bacillus thuringiensis, which produces a protein toxic to insects, in particular the European corn borer, was used to dust crops. To eliminate the need for dusting, scientists first developed transgenic corn expressing Bt protein, followed by Bt potato and cotton. Bt protein is not toxic to humans, and transgenic crops make it easier for farmers to avoid costly infestations. In 1999 controversy emerged over Bt corn because of a study that suggested the pollen migrated onto milkweed where it killed monarch larvae that ate it. Subsequent studies demonstrated the risk to the larvae was very small and, in recent years, the controversy over Bt com has switched focus, to the topic of emerging insect resistance.