BIOTECHNOLOGY VACCINE PRODUCTION
Most of the new vaccines consist only of the antigen, not the actual microbe. The vaccine is made by inserting the gene that produces the antigen into a manufacturing cell, such as yeast. During the manufacturing process, which is similar to brewing beer, each yeast cell makes a perfect copy of itself and the antigen gene. The antigen is later purified from the yeast cell culture. By isolating antigens and producing them in the laboratory, it is possible to make vaccines that cannot transmit the virus or bacterium itself. This method also increases the amount of vaccine that can be manufactured because biotechnology vaccines can be made without using live animals.
Using these techniques of biotechnology, scientists have developed antigen-only vaccines against life-threatening diseases such as hepatitis B and meningitis.
Recently researchers have discovered that injecting small pieces of DNA from microbes is sufficient for triggering antibody production. Such DNA vaccines could provide immunization against microbes for which we currently have no vaccines.
Biotechnology is also broadening the vaccine concept beyond protection against infectious organisms. Various researchers are developing vaccines against diseases such as diabetes, chronic inflammatory disease, Alzheimer's Disease and cancer.
VACCINE DELIVERY SYSTEMS
Whether the vaccine is a live virus, coat protein or a piece of DNA, vaccine production requires elaborate and costly facilities and procedures. And then there's the issue of injections, which can sometimes be painful and which many patients dislike. Industrial and academic researchers are using biotechnology to circumvent both of these problems with edible vaccines manufactured by plants and animals.
Genetically modified goats have produced a possible malaria vaccine in their milk. Academic researchers have obtained positive results using human volunteers who consumed hepatitis vaccines in bananas, and E. coli and cholera vaccines in potatoes. In addition, because these vaccines are genetically incorporated into food plants and need no refrigeration, sterilization equipment or needles, they may prove particularly useful in developing countries (see also "Plant-Made Pharmaceuticals").
Researchers are also developing skin patch vaccines for tetanus, anthrax, influenza and E. coli.
The flexibility provided by biotechnology presents many opportunities for using plants in new ways. Advances in biotechnology have made it possible to genetically enhance plants to produce therapeutic proteins essential for the production of a wide range of pharmaceuticals-such as monoclonal antibodies, enzymes and blood proteins.
Plant-made pharmaceutical production is regulated under stringent requirements of the U.S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA). The primary agency that regulates and monitors this technology is USDA's Animal and Plant Health Inspection Service (APHIS). APHIS requires companies to obtain permits for field trials for therapeutic protein production. The agency announced new permit conditions in March 2003. Prior to issuing a test permit, APHIS reviews all plans for seed production, timing of pollination, harvest, crop destruction, shipment, confinement, and the storage and use of equipment. Permits are issued for the importation, interstate movement and field testing of the plants. Field sites are inspected at least five times in a single growing season by APHIS or state officials, with those inspections corresponding to critical times in production, such as preplanting site location evaluation, planting, midseason, harvesting and postharvesting.
In 2004, 16 federal permits for growing plant-made pharmaceuticals were issued in 18 states governing 24 field sites for a total of 277 acres.
Therapeutic proteins produced by transgenic plants to date include antibodies, antigens, growth factors, hormones, enzymes, blood proteins and collagen. These proteins have been grown in field trials in a wide variety of plants, including alfalfa, corn, duckweed, potatoes, rice, safflower, soybeans and tobacco. Field trials with protein-producing plants are providing the essential building blocks for innovative treatments for diseases such as cancer, HIV, heart disease, diabetes, Alzheimer's disease, kidney disease, Crohn's disease, cystic fibrosis, multiple sclerosis, spinal cord injuries, hepatitis C, chronic obstructive pulmonary disease, obesity and arthritis.