THIRD WORLD NETWORK BIOSAFETY INFORMATION SERVICE
Dear Friends and Colleagues
Promoter Used In GM Crops Works In Salmon Over Time
The 35S CaMV promoter is derived from the “Cauliflower mosaic virus” (CaMV) and is used to drive transgene expression in most genetically modified (GM) plants. Whether the 35S CaMV promoter confers activity with respect to gene expression in lower and higher vertebrates such as fish and mammals has been a matter of debate within the scientific community.
A new study on salmon has confirmed for the first time in a vertebrate that the S35 CaMV promoter can drive expression of a transgene (reporter gene: luciferase) in Atlantic salmon. Not only did the promoter give expression of the fluorescent protein (luciferase) shortly after injection of the DNA construct, but production lasted over one and a half years. This is as long as the life cycle of the farmed fish. The study found that the DNA construct was intact at the injection site throughout the research period.
This is the first study that has shown that a plant virus promoter is also active in animals in vivo. The use of such promoters in DNA vaccines needs to be further evaluated. Consequences of the long survival of the plant DNA may be that one achieves a much more prolonged protection by using DNA vaccines than anticipated. Secondly, one should have good knowledge of the proteins and products produced by the genes in the DNA vaccine, and what effects they have on animals.
With best wishes,
Third World Network
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Malaysia
Website: https://biosafety-info.net/ and http://www.twn.my/
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Item 1
A PLANT 35S CAMV PROMOTER INDUCES LONG-TERM EXPRESSION OF LUCIFERASE IN ATLANTIC SALMON
by Tore Seternes, Tom C. Tonheim, Anne I. Myhr & Roy A. Dalmo
Scientific Reports 6, Article number: 25096 (2016)doi:10.1038/srep25096
http://www.nature.com/articles/srep25096
Abstract
The long-term persistence and activity of a naked plasmid DNA (pGL3-35S) containing a luc gene (reporter gene) controlled by a plant 35S CaMV promoter was studied in Atlantic salmon (Salmo salar L.) after injection. Atlantic salmon (mean weight 70 grams) were injected intramuscularly with 100μg of plasmid DNA. Blood, different tissues and organs were sampled at different time points up to day 535 after injection. Southern blot analysis suggested the presence of extra-chromosomally open circular, linear and supercoiled topoforms of pGL3-35S at day 150 after injection. At day 536 open circular and supercoiled topoforms were detected. Luciferase activity was detected at the injection site up to 536 days post-injection of pGL3-35S, where it peaked at day 150 and decreased to approximately 17% of its maximum activity by day 536. Our study demonstrated that a plasmid containing the 35S promoter was able to induce expression of a reporter gene/protein in fish in vivo and that the plasmid DNA persisted for a prolonged time after intramuscular injection.
Item 2
NEW STUDY SHOWS THAT PROMOTER USED IN GM CROPS WORKS IN SALMON OVER TIME
GenØk-Centre for Biosafety, Norway
http://genok.com/arkiv/5316/
A new study in salmon has confirmed for the first time in a vertebrate that the S35 CaMV promoter, such as is used in most GM crops, is able to drive expression of a transgene, and that the duration of transgene production is at least 1.5 years in the salmon.
In this study Tore Seternes and Roy A. Dalmo (UiT the Arctic University of Norway), Tom Christian Tonheim (Marine Harvest) and Anne I. Myhr (GenØk) found that the plant virus promoter CaMV can also drive expression of a transgene (reporter gene: luciferase) in Atlantic salmon. The promoter is derived from “Cauliflower mosaic virus” (CaMV) and is often used in genetically modified plants. Not only did the promoter give expression of the fluorescent protein (luciferase) shortly after injection of the DNA construct, but production lasted over one and a half years. This is as long as the life cycle of the farmed fish. They found that the DNA construct was intact at the injection site throughout the research period.
This is the first study that has shown that a plant virus promoter is also active in animals in vivo, and this promoter can therefore be an alternative to some of the other promotors used in DNA vaccines. Canada has approved a DNA vaccine that can be used to protect salmon against IHN virus and the European Medicines Agency just granted marketing authorization for a DNA vaccine that can protect salmon against pancreas disease (PD). There are many advantages of DNA vaccines; they are easy to produce, and a DNA vaccine can be used as a starting point by replacing a gene with a new gene from the virus or bacterium (possibly infectious agent) one wishes to prevent disease from. Until now, virus promoters that infect animals are frequently used in experimental DNA vaccines for fish. One example is the cytomegalovirus (family: Herpesviridae) promoter (CMV promoter), which is a strong promoter that can drive the expression of a desired disease protective antigen. The CMV promoter is, however, not desirable to use in DNA vaccines, as it is known that e.g. human cytomegalovirus may produce undesirable effects. Consequences of the long survival of the plant DNA may be that one achieves a much more prolonged protection by using DNA vaccines than anticipated. Secondly, that one should have good knowledge of proteins and products produced by the genes in the DNA vaccine, and which effect they have on salmon.