ISIS Press Release 28/11/05
Immune Reactions to Transgenic Protein Serious
Independent Scientists Demand A Ban on GM Food & Feed while All GM
Crops Are Tested
The following memo and report were sent to international and
national regulators on behalf of the Independent Science Panel.
Please circulate widely, forward to your regulators and policy
makers, and the press.
From: Dr. Mae-Wan Ho, member of Independent Science Panel (www.indsp.org), Director, Institute
of Science in Society (www.i-sis.org.uk)
To: (see list at the end)
I am writing on behalf of the Independent Science
Panel (ISP)* to draw your attention to new research findings on the safety
of transgenic proteins that need to be urgently addressed.
Specifically, immunological
assessments carried out for the first time on a transgenic protein revealed
that post-translational processing
subsequent to gene transfer into an alien species introduced new antigenicities
that turned a previously harmless protein into a strong immunogen. In addition,
the transgenic protein promoted immune reactions against multiple other proteins
in the diet. The detailed findings are reviewed in the report below.
As practically
all the transgenic proteins involve cross-species gene transfer, they will
be subjected to different post-translational processing, and hence they too,
will have the potential to become immunogenic. And yet, none of the transgenic
proteins that have been commercially approved has been tested. This omission
is a most serious public health issue.
We call on you to impose an immediate
ban on all GM food and feed until proper assessment on the immunogenicity
of all the transgenic proteins has been carried out.
*The ISP, launched 10 May 2003 at a public
conference in London, UK, consists of dozens of prominent scientists from
11 countries spanning the disciplines of agroecology, agronomy, biomathematics, botany, chemical medicine, ecology,
epidemiology, histopathology, microbial ecology, molecular genetics,
nutritional biochemistry, physiology, toxicology and virology (http://www.indsp.org/ISPMembers.php)
Transgenic Pea that Made Mice Ill
Raises serious safety concerns on transgenic proteins in general that must
be addressed while a ban on all GM food and feed is imposed. Dr.
Mae-Wan Ho
Ten-year project down the drain but are the right lessons learned?
A ten-year project at CSIRO (Commonwealth Scientific
and Industrial Research Organization) in Canberra Australia
bit the dust when peas modified to resist insects caused inflammation in the
lungs of mice [1]. The GM peas will be destroyed, said Gene Technology Regulator
Sue Meeks.
The gene coding for the
protein, a-amylase
inhibitor-1 (aA1)
in the common bean (Phaseolus vulgaris
L. cv. Tendergreen), was inserted into pea (Pisum
sativum L.) to make the pea-plants resistant to attack from weevils.
Dr. T.J. Higgins,
deputy chief of CSIRO Plant Industry and co-author of the scientific paper
reporting the results remarked it is only the second time in the world that
a GM project has been abandoned after a gene transfer from one crop to another,
and that it demonstrated the effectiveness of strict regulations on research
into GM crops.
Greenpeace campaigner
Jeremy Tager said: “It just shows the failure of the science in relation to
this gene product.”
Director of GeneEthics
Network Bob Phelps referred to the project as a “waste of public money” and
highlights the growing concern worldwide about the health impacts of all GM
foods.
There are indeed
important lessons to be learned from the scientific findings [2], which raise
serious safety concerns over transgenic proteins in general.
Different processing of transgenic protein
The researchers found that
the transgenic protein was processed differently and provoked immune reactions
not exhibited by the native protein (see later).
Transgenic aA1 protein was compared with the non-transgenic
protein on Western blot, a technique that separates different forms of the
protein arising from post-translational processing. Previous studies showed
that the native polypeptide in bean is cleaved into two chains, a and b, both of which are
glycosylated (carbohydrate chains added), and with one or more amino acids
removed from the tail end. This results in major forms of the a- and b-chains with molecular
masses 11 646 Da and 17 319 Da respectively, together with minor forms containing
alternative carbohydrate chains. The transgene in pea yielded a- and b-chains with molecular
masses in the11 000 – 18 000 Da region, but with a banding pattern different
from the native protein. More detailed comparisons on mass spectroscopy showed
that the transgenic a-chain was less heavily glycosylated;
and a form with two fewer mannose residues (11 322 Da) was the dominant in
transgenic pea, but the least abundant in bean. The b-chain in the transgenic protein also
showed a number of other bands besides the major and minor forms present in
the native protein.
Immune reactions to transgenic protein
Mice were given about 25mg
of seed meal in suspension, containing transgenic pea, nontransgenic pea,
or bean, twice a week for 4 weeks. Seven days after the final feeding, the
mice were subcutaneously injected in the footpad with the purified protein
antigens: native or transgenic aA1, and the swelling induced in the footpad assessed 24
h later.
In a second experiment, the mice were fed seed meal suspensions
as before, and seven and nine days after the final meal, purified transgenic
aA1
or buffered saline was introduced into the trachea, and inflammation response
was measured in the lungs 24 h later.
The results showed that mice fed on non-transgenic pea
or bean showed no inflammation response in the footpad or in the lungs, indicating
normal immune tolerance to common food.
Mice fed with transgenic pea, however, showed aA1-specific IgG antibodies
at two weeks, rising to significant levels after 4 weeks. There was significant
swelling of the footpad, or delayed type hypersensitive (DTH) response, when
purified aA1
was injected. Similarly, introducing the antigens into the trachea gave an
inflammation response in the lungs.
As a control for the general effect of genetic modification,
the footpad challenge experiment was repeated with material from two other
GM plants, lupin expressing sunflower seed albumin (SSA) and chickpeas expressing
aA1.
In contrast to transgenic pea, mice fed transgenic lupin or transgenic chickpea
did not give DTH response. This shows that the response to transgenic pea
was specific.
The peribronchial lymph nodes of the mice were tested
for their response to transgenic aA1. Only the lymph nodes of mice fed
transgenic peas responded by producing the inflammation cytokines (cell signalling
factors) when challenged with transgenic aA1.
Transgenic protein promotes reactions to other proteins
In order to test if the
transgenic protein promotes immune reactions to other proteins in the diet,
mice were fed purified transgenic or native aA1, or transgenic aA1 with or without ovalbumin three times
a week for 2 weeks. One week following feeding, purified ovalbumin or buffered
saline were introduced into the trachea of the mice, and inflammation response
in the lungs was assessed as before.
Neither ovalbumin alone, nor ovalbumin in combination with native aA1 caused any inflammation response in the footpad or lungs
when the mice were challenged with ovalbumin. However, consumption of transgenic
aA1 and ovalbumin together promoted a strong ovalbumin-specific
antibody response and predisposed the mice to inflammation when challenged with
ovalbumin in both the footpad and the trachea. This suggests that transgenic
aA1 did promote reactions to other proteins. In confirmation
of that, levels of antigen-specific IgG against other proteins such as pea globulins,
lectin, and vicilin-4 were also significantly higher in the serum of mice fed
transgenic pea than mice fed non-transgenic pea.
Wider implications on the safety of transgenic proteins that must be addressed
The transgenic pea involved
gene transfer between plant species, and is generally thought to be much safer
compared with the cross-kingdom gene transfer – bacteria to plant – involved
in the GM food crops that now cover tens of millions of hectares worldwide.
A harmless bean protein expressed in transgenic pea caused
inflammation in mice, and research showed that the most likely reason is because
the protein is processed differently in peas. Such post-translational processing of proteins is well known to be species-specific,
and as genetic modification almost invariably involves cross-species transfer
of proteins, one must expect transgenic proteins to differ structurally from
the native proteins as a matter of course. Are they also likely to provoke immune reactions as
a result?
It would not happen in every case, as the researchers
have found that neither transgenic lupin sunflower seed albumin, nor transgenic
chickpea aA1
gave the same results as transgenic pea aA1. But how frequently could it happen?
“Currently, we do not know the frequency at which alterations
in structure and immunogenicity of transgenically expressed proteins occur
or whether this is unique to transgenically expressed aA1.” The researchers
admitted.
Furthermore, when consumed with other proteins, the transgenic
pea protein promoted immunological ‘cross-priming’ against those proteins,
so that the mice developed specific immunological reactions to them as well.
In other words, the transgenic protein can provoke generalised immune
response to multiple proteins in the diet, whether transgenic or not.
The previous instance of a GM project being abandoned
was the transfer of a Brazil nut allergen into soya [3], and it involved a
known allergen. The present case involves a protein that has all the appearance
of being harmless.
As yet, no other GM crop,
especially those already out there in the fields and in our food and feed,
has been tested in this way. This must now be done. Meanwhile,
there must be a ban imposed on all GM food and feed.
References
- 1.
“GM crops scrapped as mice made ill”, Selina Mitchell
and Leigh Dayton, The Australian, 18 November 2005. http://www.theaustralian.news.com.au/common/story_page/0,5744,17283002%255E2702,00.html
- Prescott VE, Campbell
PM, Moore A, Mattes J, Rothenberg ME, Foster PS, Higgins TJV and Hogan SP.
Transgenic expression of bean a-amylase inhibitor in peas results in altered
structure and immunogenicity. J Agricultural and Food Chemistry 2005,
53, 9023-30.
- Nordlee JA, Taylor SL, Townsend JA, Thomas LA & Bush
RK. Identification of a brazil-nut allergen in transgenic soybeans. The New England Journal of
Medicine
1996, March14, 688-728.
Sent to:
Mr. Hamdallah Zedan, Executive Secretary, Secretariat of the
Convention on Biological Diversity, secretariat@biodiv.org
Cc: Mr. David Cooper, Senior Programme Officer – Interagency
and Program (UK and Northern Ireland), david.cooper@biodiv.org
Mr. Geoffrey Podger, Executive Director, European Food Safety Authority
Geoffrey.podger@efsa.eu.int
Cc: Mr. Herman.Koeter, Director of Science, European Food
Safety Authority, Herman.koeter@efsa.eu.int
Dr. Harry Kuiper, Chair of the GMO Panel, EFSA, h.a.kuiper@rikilt.wag-ur.nl
Colin Ross, Food Standards Agency, UK, colinRoss@foodstandards.gsi.gov.uk
Cc: Elliot Morley MP, Minister for the Environment, Emorley@aol.com
Rt. Hon Michael Meacher MP, meacherm@parliament.uk
Canadian Food Inspection Agency, Plant Products Directorate, Plant Biosafety
Office, pbo@inspection.gc.ca
Cc:Hon Andrew Mitchell, Minister of Agriculture and Agri-Food
and Minister of State (Federal Economic Development Initiative for Northern
Ontario), Mitchell.A@parl.gc.ca
Mr. Mike Johanns, Secretary of Agriculture, USDA, United States
Mike.Johanns@usda.gov
Cc: Dr. Ron DeHaven, Animal and Plant Health Inspection Service
Ron.DeHaven@usda.gov
Mr. Stephen L. Johnson, Environment Protection Agency, USA
johnson.stephen@epa.gov
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