The secret viral gene in most GM crops

March 2013

Electron micrograph of CaMV virions
Image By Patou2602 (Own work)
[CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)]
via Wikimedia Commons

Fourteen years ago, the Institute of Science in Society (ISiS) issued a warning. It pointed out that the artificial genes in most GM crops are activated by a very problematic stretch of viral DNA copied and adapted from a plant pathogen, the cauliflower mosaic virus (CaMV).

This activator DNA, commonly referred to as the 'CaMV 35S promoter', is able to switch on genes in most, if not all, life-forms: it also has an inherent tendency to fragment and recombine with other DNA. Outside its viral-particle origins, the potential for these characteristics to promote horizontal gene transfer, create new pathogens or drive inappropriate gene expression must exist. Moreover, synthetic versions of CaMV 35S have been rejigged to boost gene expression: this increases the risk of all the above properties of the promoter.

The ISiS warning drew a, now familiar, orchestrated deluge of critiques (including one from Monsanto), which “varied from moderately polite to outright abusive”.

By 2013, with CaMV 35S DNA sequences now present in more than 60% of commercialised GM crops, a new risk assessment was published. Aware that the promoter contains a sequence of DNA which is actually a fragment of one of the CaMV genes ('gene VI'), scientists belatedly checked whether inadvertent expression might produce proteins which are toxins or allergens.

No such hazard was identified from comparisons with reference chemical databases. However, the authors did note that putative gene VI proteins might alter the characteristics of the GM plant in other unpredictable ways.

This opened up another can of GM worms.

Viruses such as CaMV are pathogenic, DNA-based particles. Unlike the coherent metabolic processes needed for organisms to exist and successfully reproduce, viruses are designed purely to replicate themselves uncontrollably. To help them invade and commandeer cells for this purpose, viruses require to be as small and simple as possible, and their minimalisation is achieved by economising on DNA. CaMV has only six genes, but each of these is multi-purpose, and the DNA sequences can even overlap. Also unlike the genes of organisms copied by biotech scientists, viral genes don't have their own 'start' and 'end' markers.

Our knowledge about gene VI so far, indicates that the sequence which is present in the CaMV promoter is the most active part of the gene.

Without its own 'start' sequence, the fragment would, of course, need a trigger to express itself. However, in a world of unstable synthetic CaMV 35S, DNA recombination, and other ambient viruses, the possibility of it linking up to an 'on-switch' isn't vanishingly small.

This begs the question, if and when the gene VI fragment is expressed (either in a crop or in another virus), what might happen? The list of possibilities suggested so far, doesn't make comfortable reading:

• The evolution of plant super-viruses is top of the list. This is because gene VI is known to form the cellular bodies needed for virus replication and assembly.
• Weakened crop plants are a close second. This is because gene VI is known to stimulate mass random protein production
• A diseased crop may be regarded as a certainty. This is because gene VI is known to damage plants' immune system.
• The emergence of increasingly abnormal crop plants are a serious concern. Gene VI inserted into a GM plant in the laboratory produces aberrations. This is because gene VI can inappropriately silence or stimulate plant genes.
• Given all the disruptions described above, toxins and allergens in food are a strong possibility.

 

OUR COMMENT

This aspect of the artificial DNA in GM crops should have been risk-assessed decades ago, before all commercialisation.

Since gene VI and at least some of its functions have been studied for a long time, the presence of a fragment in GM crops must have been known to its producers and regulators. Both chose to ignore the implications.

Misinformation from the European Food Safety Authority (EFSA) in response to media reports about the study is revealing. In answer to its own question “What is the viral gene discussed in the paper?” it starts out well by telling readers that “The viral gene (Gene VI) belongs to a plant virus (Cauliflower Mosaic virus)”. Then it starts to fudge the issue by going on to explain, that the virus (not the gene) “cannot infect animals or humans”. This inappropriate logic continues with “therefore presents no threat to human or animal health”, ending with the completely irrelevant information that “This virus (not the gene) naturally infects many plants with no recorded health effects”.

This might make you question whether the EFSA has even the most rudimentary knowledge of the GM issues it's supposed to be regulating. Or, perhaps someone's twisting it's arm to appear stupid?

If you find it difficult to accept that such a powerful body could be spinning such yarns, it might be helpful to read 'Conflicts of interest at the European Safety Authority erode public confidence'. This article was recently commissioned by the Journal of Epidemiology and Community Health. Check it out at:

http://jech.bmj.com/content/early/2013/03/07/jech-2012-202185.extract

SOURCES:

• Muriel Haas, et al., 2005, The Open Reading Frame VI Product of Cauliflower mosaic virus Is a Nucleocytoplasmic Protein: Its N Terminus Mediates Its Nuclear Export and Formation of Electron-Dense Viroplasms, The Plant Cell, Vol 17, March 2005
• Johannes Fűtterer, et al., 1996, Position-Dependent ATT Initiation during Plant Pararetrovirus Rice Tungro Bacilliform Virus Translation, Journal of Virology, May 1996
• Mae-Wan Ho, Hazardous Virus Gene Discovered in GM Crops after 20 Years, Institute of Science in Society Report 28.01.13
• Nancy Podevin and Patrick du Jardin,2012, Possible consequences of overlap between the CaMV 35S promoter regions in plant transformation vectors used and the viral gene VI in transgenic plants, Landes Bioscience Journal, 3:4, Oct-Dec 2012
• FAQ on inserted fragment of viral gene in GM plants, www.efsa.europa.eu
• Hidden viral gene revealed in GMOs - EFSA's “review” not enough, GM Freeze Press Release 21.01.13
• J. R. Latham, Regulators Discover a Hidden Viral Gene in Commercial GMO Crops, Independent Science News, 21.01.13
• Latham and Wilson, Potentially Dangerous Virus Gene Hidden in Commercial GM Crops, Institute of Science in Society Report, 29.01.13
• Hidden Viral Gene Found in GMOs: Q&A, GM Freeze, 11.03.13
• Sean Poulter, Uncovered, the 'toxic' gene hiding in GM crops: Revelation throws a new doubt over safety of foods, Daily Mail, 21.01.13