GENE THERAPY AS A TREATMENT FOR HUMAN DISEASE

The possibility of Gene Therapy in Medicine began with the discovery by Zinder and Lederberg in 1953 that genetic characteristics can be transferred from one bacterial strain to another. In these early experiments, it was found that if a virus (bacteriophage), that had infected one bacterial strain, was used to infect a second bacterial strain, the virus would transfer a genetic characteristic to the second bacterial strain that it had "picked-up" from the first. The virus physically removes a gene (piece of DNA) from the first bacterial strain and inserts this gene into the DNA of the second strain. Thus, the transferred gene is now expressed in the second bacterial strain. This genetic transfer process was subsequently called Transduction, and the virus, generally in this process, a vector.

The question has been: Could this gene transfer take place in humans? The answer, of course, was yes. Thus began Gene Therapy and the possibility of using a viral vector to "correct" a genetic disease, and, as well, their use in the treatment of canser and infectious diseases such as AIDS. Vectors now are routinely (literally) constructed in the laboratory from various viruses.

But, the Transduction process has always posed serious risks if used to treat human diseases. These risks have as their bases:

  1. an immune response to the viral vector that induces a potentially lethal autoimmune reaction,
  2. the viral vector, while inactivated, could revert to the disease causing virus from which it was derived, and,
  3. the vector inserts itself, and the DNA that it carries, randomly into the DNA of the host. This random insertion can cause mutations in the host DNA seriously disrupting the metabolism of a cell, cause a cancer, or may be lethal.

These problems are not trival biological problems. They need to be looked at with extreme caution in animal models before using this strategy, if at all, to treat human disease. At present, it's like flipping a coin; hoping that the vector itself will be benign. That is not acceptable Science or Medicine.