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The hazards of horizontal gene transfer
- Unregulated Hazards ‘Naked’ and ‘Free’ Nucleic Acids

Horizontal gene transfer is uncontrollable. Unlike chemical pollutants which break down and become diluted out, nucleic acids are infectious, they can invade cells and genomes, to multiply, mutate and recombine indefinitely.

Horizontal gene transfer is by no means unknown to our Governments. Among the scientific advice given by the UK Ministry of Agriculture, Fisheries and Food (MAFF) to the US Food and Drug Administration (FDA) at the end of 1998 [62] are the following warnings:

  • Transgenic DNA can spread to farm workers and food processors via dust and pollen.
  • Antibiotic resistance marker genes may spread to bacteria in the mouth, as the mouth contains bacteria that readily take up and incorporate foreign DNA (see above). Similar transformable bacteria are present in the respiratory tracts.
  • Antibiotic resistance marker genes may spread to bacteria in the environment, which then serves as a reservoir for antibiotic resistance genes.
  • DNA is not readily degraded during food processing nor in the silage, hence transgenic DNA can spread to animals in animal feed.
  • Foreign DNA can be delivered into mammalian cells by bacteria that can enter into the cells.
  • The ampicillin resistance gene in the transgenic maize undergoing ‘farm-scale’ field-trials in the UK and elsewhere is very mutable, and may compromise treatment for meningitis and other bacterial infections, should the gene be transferred horizontally to the bacteria. The potential hazards of horizontal gene transfer are unlike those we have ever experienced (see Box 5).

The dangers of generating new viruses and bacteria that cause diseases, and spreading drug and antibiotic resistance among the pathogens, were both foreseen by the pioneers of genetic engineering. That was why they called for a moratorium in the Asilomar Declaration of 1975. But commercial pressures cut the moratorium short, and guidelines were set up based on assumptions, every one of which has been invalidated by scientific findings since [63]. Within the past 20 years, drug and antibiotic resistant infectious diseases have come back with a vengeance. Geneticists have confirmed that the diseases are due to new viral and bacterial strains that have been created by horizontal gene transfer and recombination. Horizontal gene transfer is now recognized to be widespread, involving the entire biosphere, with bacteria and viruses in all environments serving as reservoir and highway for gene multiplication, gene swapping and trafficking. Has genetic engineering contributed to creating the new pathogens, and will it continue to do so through the unregulated release of naked and free nucleic acids? [64] The possible links between genetic engineering biotechnology and the recent resurgence of infectious diseases are summarized in Box 6.

Dormant and relict viral sequences have been discovered in the human and other animal genomes at least 20 years ago [65]. Viral sequences have also been discovered recently in plant genomes [66]. Viral transgenes are found to recombine with defective viruses to generate infectious recombinants [67]. Recombination between exogenous and endogenous viral sequences are associated with animal cancers [68]. It is not inconceivable that the cauliflower mosaic viral promoter, which is in practically all first generation of transgenic plants, may recombine with dormant/relict viral sequences in the genome to regenerate infectious viruses [69], in view of the fact that viral promoters have modules in common. Recombination hotspots may be associated with all transcriptional promoters [70], including those of animal viruses, such as the SV40 and cytomegalovirus, used in animal and human genetic engineering [71]. This possibility should be addressed by empirical investigations, particularly in view of the recent claim that a significant part of the toxicity of certain transgenic potatoes fed to young rats may be due to the transgenic construct or the transformation process, or both [72].

In the light of the existing evidence, the most dangerous naked/free DNA may be coming from the wastes of contained users of GMOs which are discharged into our environment. These include constructs containing cancer genes from laboratories in research and development of cancer and cancer drugs, virulence genes from bacteria and viruses in pathology labs and all kinds of other novel constructs and gene combinations that did not previously exist in nature, and may never have come into being but for genetic engineering.

Despite the growing body of evidence of hazards from the innumerable exotic naked nucleic acids that are created and released in increasing amounts into the environment from the burgeoning biotech industry, there is no effective regulatory oversight, nor is there any indication that our Government is prepared to establish effective regulatory oversight (see Box 7).


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