Scientists take these vectors and splice in all the genes we've mentioned above - the desired gene, the marker gene, and promoter genes. Then they let the vector do the work, invading the target cells and depositing the new genes into the cell's genome. This often results in insertion of multiple copies of the new genetic construct, which may exacerbate the harmful and unpredictable effects. In one case, according to the International Journal of Food Science and Technology, duplicate genes caused a strain of GE yeast to become mutagenic. In splicing genes that make a plant resistant to viral diseases, biotech scientists can inadvertently create new, potentially deadly viruses.
Viruses consist of genetic material covered by a protein coat.
For an unknown reason, when scientists insert the genes for a virus's coat protein into a plant's genetic make-up, the plant can resist a virus it had been susceptible to. In that process, the genetic material from one type of virus becomes enveloped in the protein coat of another kind. With the splice, the plant has been given a gene for a new virus protein coat. Any virus that happens by could try on the protein coat. A virus wearing someone else's coat could infect an individual that would normally recognize and resist it, since resistance is based on the coat, not the innards.