Back

Lawrence writes about cheese, DEFRA's vainglory, and vaccine.

I joined Karen, doing duty on our stand at the Devon Show on Saturday. We had a space in the Devon Foodlinks part of the Devon County Council display. It was a very successful tent, full of 11 local producers, most of them farm based, with a very impressive range of foods. So Devon County Council does have its good points. [I suppressed my enmity to the public rights of way section which seemed to be exhibiting in the adjacent tent.] It is so long since I have been out of the farm, meeting people, that the day just about finished me. I don't know how Karen managed to survive the whole three days [but she had some preparation in the pannier markets over the previous week or two]. There was a constant flow of interested people passing through. We sold a lot of cheese - the hard way - in 100 grammes at a time slices [that is the other problem - working out change under pressure!] - and handed out at least 300 leaflets about the farm over the 3 days.

We managed brief forays out into the show. Very strange to be at an agricultural show with no cattle or sheep. There was a tent of guinea pigs and hampsters - not really a substitute.

Then there was the DEFRA stand... enormous and grandiose. Neither of us could bear to venture onto it. Besuited officials awaited on a podium raised high above the ground level, surrounded by walls of poster and photograph displays in symmetrical pomp. Karen commented that it looked as if it was throwback to the Third Reich. It looked like a photo from the period brought to life, with its overblown self importance. In my recollection, my imagination keeps adding Neo Classical columns to the symmetrical facade. Not many people had been drawn to walk up the grand stairways when I passed by. Another World - a brave new one, perhaps?

Thinking of which, I found these articles while searching under 'Pharmacia', parent company of Monsanto and many others...

The first, dates from March, and you may have seen it. It was short enough to copy below. The second is longer and I have attached a text only version of it which does not do justice to the tables and illustrations. It can be found at http://www.socgenmicrobiol.org.uk/JGVDirect/17505/17505ft.htm#SUMMARY [It also notes that This article is now available in the July 2001 print issue of the Journal of General Virology (vol. 82, 17131724). The complete issue of the journal may be seen in electronic form on JGV Online.] First posted online 9 April 2001 FULL-LENGTH ARTICLE Rec 31 October 2000; Acc 30 March 2001 DOI: 10.1099/vir.0.17505-0

Induction of a protective response in swine vaccinated with DNA encoding foot-and-mouth disease virus empty capsid proteins and the 3D RNA polymerase Leticia Cedillo-Barrsn,1 Mildred Foster-Cuevas,1 Graham J. Belsham,1 Frangois Lhfevre2 and R. Michael E. Parkhouse1'

1 Institute for Animal Health, Pirbright Laboratory, Pirbright, Surrey GU24 0NF, UK
2 INRA Virology et Immunologie moliculaires, INRA, 78350 Jouy-en-josas,
France.

The Summary is as follows - ------------------------------------------------------------------------------ --

This work focuses on the development of a potential recombinant DNA vaccine against foot-and-mouth disease virus (FMDV). Such a vaccine would have significant advantages over the conventional inactivated virus vaccine, in particular having none of the risks associated with the high security requirements for working with live virus. The principal aim of this strategy was to stimulate an antibody response to native, neutralizing epitopes of empty FMDV capsids generated in vivo. Thus, a plasmid (pcDNA3.1/P12A3C3D) was constructed containing FMDV cDNA sequences encoding the viral structural protein precursor P12A and the non-structural proteins 3C and 3D. The 3C protein was included to ensure cleavage of the P12A precursor to VP0, VP1

and VP3, the components of self-assembling empty capsids. The non-structural protein 3D was also included in the construct in order to provide additional stimulation of CD4+ T cells. When swine were immunized with this plasmid, antibodies to FMDV and the 3D polymerase were synthesized. Furthermore, neutralizing antibodies were detected and, after three sequential vaccinations with DNA, some of the animals were protected against challenge with live virus. Additional experiments suggested that the antibody response to FMDV proteins was improved by the co-administration of a plasmid encoding porcine granulocytemacrophage colony-stimulating factor. Although still not as effective as the conventional virus vaccine, the results encourage further work towards the development of a DNA vaccine against FMDV.

The article describes how the experimental animals were infected and the results. It states: "This work was supported by EECFAIR grant 1317. We are grateful to Dr Paul Barnett from the International Vaccine Bank, IAH, Pirbright, for useful discussions and for providing FMDV antigen and to Bob Statham for preparation of FMDV vaccine. We would also like to thank Sarah J. Cox for performing the neutralizing antibody test. We are also grateful to the IAH animal caretakers for their help with animal handling." I wonder where the experiments were conducted. It is clearly part of continuing research and must illustrate the sort of thing that is going on all the time...

Lawrence.

¤ Date: 6 Mar 2001 19:18:53 -0600
From: jcummins
Subject: foot and mouth transgenic edible vaccines

March 6, 2001 Prof. Joe Cummins e-mail: jcummins@uwo.ca

"Foot and mouth disease transgenic edible vaccines: Solution or problem" The recent outbreak of foot and mouth virus (FMDV) has led many to wonder whether or not there was a connection between the outbreak and experiments in genetic technology. There have been experiments done using transgenic constructions to construct edible vaccines to treat the disease. Field testing such constructions does not fall under regulations governing transgenic crops used for food. It is worth enquiring of the governments of countries about the studies, if any, being undertaken.

The transgenic vaccines reported have been transgenic alfalfa with foot and mouth virus structural proteins (Wigdorovitz et al a 1999), plants infected with tobacco mosaic virus genetically altered with FMDV structural protein (Wigdorovitz et al b1999) or bacterial plasmids containing genes for FMDV protein (Wong et al 2000). Use of genetically modified (GM) organisms to deliver edible vaccines has proven effective in protecting farm animals but the procedure is not without drawbacks. One complication with oral vaccines is called "oral tolerance". When antigens are taken up in food repeatedly the antigen may suppress production of antibody. In autoimmune diseases such as arthritis, diabetes and multiple sclerosis antigens are produced in target tissues leading to disease. When quantities of the target antigen , such as collagen in arthritis, is fed the autoimmune disease is suppressed and many patients experience relief. Indeed, antigens for autoimmune disease are being introduced into crop plants to treat the symptoms of autoimmune disease. However, oral vaccines in regular food supplies may suppress immunity to the disease normally protected by the vaccine(Langridge 2000, Weiner 1997). Measures must be taken to prevent the spread of food vaccines to the general food supply. Transplacental exposure to the edible vaccine may cause the fetus to be tolerant to the virus to the extent that the animal may become a carrier of the virus without showing symptoms ( an example of a carrier might be "typhoid Mary" of elementary texts).

The crops modified to be used as edible vaccines should be scrupulously maintained for that purpose alone. Recently corn modified as an edible vaccine for a swine virus was promoted by the company inventing it. It was promised that the GM corn would be grown under "rigorously controlled conditions and used only for the expressed purpose of vaccine production"("Edible Vaccine Success" In Brief Nature Biotechnology 18,367,2000). Such commitment is essential but such promises should be viewed in the light of StarLink corn that was approved only for animal consumption but appeared in foods for human consumption. GM crops as edible vaccines should be restricted to plant tissue culture or to contained plant growth chambers or high security greenhouses. In conclusion, edible vaccines for FMDV have been tested and described in the scientific literature. Edible vaccines are effective but have potential side effects that may actually contribute to spread of the disease. Government regulators should make any experiments with edible vaccines public.

References Landridge,W "Edible Vaccines" 2000 Scientific American on line Sept. Weiner,H. "Oral tolerance for treatment of autoimmune diseases" 1997 Ann Rev Med 48,341-51 Wigdorovitz,A,Carrillo,C,DusSantos,M,Trono,K,Peralta,A,Gomez,M,Rios,R,Franzone

,P,Sadir.A,Escribano,J

and Borca,M "Induction of a protective antibody response to foot and mouth disease virus in mice following oral or parenteral immunization with alfalfa transgenic plants expressing the viral structural protein VP1" 1999 aVirology 255,347-53 Wigdorovitz,A,Perez Filgueira, Roberson,N,Carrilo,C, Sadir,A, Morris,T and Borca,M "Protection of mice against challenge with foot and mouth disease virus (FMDV) byy immunization with foliar extracts of plants infected with recombinant tobacco mosaic virus expressing the FMDV structurl protein VP1" 1999b Virology 264,85-91 Wong,T,Cheng,E,Chan,Z,Sheng,W,Yan,W,Zheng,Z and Xie,Y "Plasmids encoding foot and mouth disease virus VP1 epitopes elicited immune responses in mice and swine and protected swine against viral infection" 2000 Virology 278,27-35

Back