Recombinant DNA refers to DNA molecules in which sequences which are not naturally contiguous have been placed next to each other by in vitro manipulations. The different sequences within a recombinant DNA molecule will frequently have come from entirely different organisms. A critical component of gene therapy is the delivery of the genes to the body. Genes have to be inserted into a cell's nucleus. During the 1960s, researchers contemplated the use of viruses, normally an enemy, as an agent for delivery of genes.
Viruses replicate themselves by invading a cell's DNA and inserting their own genetic code.
Animal gene therapy trials are currently underway as possible therapy for cystic fibrosis. In 1980, a consortium of Protestant, Catholic and Jewish groups sent a letter to President Jimmy Carter expressing concerns about genetic engineering and maintaining the fundamental nature of human life and dignity of the individual. Debate leading up to creation of the document was sparked by a breakthrough in developing a viral vector. Scientists were concerned about the potential risks of re-engineering viruses and the possible creation of a new infectious disease. Some might argue that we were too cautious, but the question could not be answered until the experiments were done.