Genetic engineering can theoretically correct that deficit. Unfortunately, "the technology for such output traits is complicated," says Ganesh M. Kishore, vice-president for technology, agriculture, and nutrition at DuPont (DD
) So producers of gene-spliced crops have focused instead on plants that are able to fight pests or tolerate herbicides.
Now, DuPont researchers say they have succeeded in adding a single gene to corn that causes the grain to boost production of no less than four amino acids. The company has also added the genes for lysine and methionine to soybeans, successfully fashioning plants that make more of these amino acids. The soybeans are already being tested in the field, and the new corn will be planted this year, says Kishore. The first use of these crops, he anticipates, will be as animal feed. Now that scientists have read the human genome, drugmakers are faced with a surprising problem: too many potential targets for drugs. Even one disease, such as diabetes, may involve 100 or more genes. Companies have spent years developing drugs only to learn they are hitting the wrong genes or proteins.
Isis Pharmaceuticals (ISIS
) in Carlsbad, Calif., claims it can deal with this complexity. The idea is to hit all the potential targets in a disease. "We can begin with a set of unknown genes and be in the clinic in less than 12 months," says Isis CEO Dr. Stanley Crooke.
Isis scientists make strands of DNA, called antisense DNA, that block genes from making their proteins. By creating a collection of antisense compounds, researchers can disable each gene in a disease.
That points the way to promising treatments. Working in diabetes, the company has found an antisense drug that reduces high glucose levels without allowing blood sugar to drop too low -- a common problem with current drugs. To treat heart disease, doctors often open up or replace blocked arteries. But there may be a better way: growing new blood vessels. "That would be truly spectacular technology if it could be delivered," says Michael A. Mussallem, CEO of Edwards Lifesciences (EW
It hasn't been done yet. But one promising tack comes from Sangamo BioSciences in Richmond, Calif., whose technology is licensed to Edwards Lifesciences. The idea is to turn on the body's own gene for a protein called vascular endothelial growth factor (VEGF), which prompts the formation of new blood vessels. Sangamo scientists have designed proteins, called transcription factors, that bind to specific bits of DNA. Hit the right spot, and the targeted gene is activated.
In one experiment at Duke University, researchers used the transcription factor drug to turn on the gene for VEGF in rabbits, after removing an artery in one leg of each animal. The result: more vessels and increased blood flow to the legs after being treated. "We are extremely excited about the data," says Dr. J. Tyler Martin, Sangamo's vice-president for development. The company expects to apply to the FDA within a year to test the drug in people with damaged blood vessels in their legs. Ten years ago, Genvec (GNVC
) was founded to cure disease by delivering new genes to people with illnesses such as cystic fibrosis. So far, such gene therapy hasn't led to products. But the Gaithersburg (Md.) company believes its technology will pay off -- in vaccines.
The approach starts with a weakened version of a microbe called an adenovirus. Into this, scientists insert genes for a deadly bug, such as HIV. People who are given the rejiggered adenovirus won't contract AIDS. The added genes prompt cells to make HIV proteins, stimulating an immune response that may protect against infection.
GenVec has been working with the National Institutes of Health on an AIDS vaccine. But when the SARS epidemic hit, CEO Paul H. Fischer realized that his technology could be quickly adapted for the new illness. All the company's scientists needed was the genetic sequence. "For SARS or any other rapidly emerging biothreat, we can go directly from the genetic blueprint to make a synthetic gene and put it in the adenovirus vector," he explains.
In 15 days, GenVec hammered out an agreement with the NIH to make the vaccine against SARS.