Gene Transfer and Cauliflower Mosaic Virus Promoter 35S Activity in Mammalian Cells

Abstract

The cauliflower mosaic virus 35S promoter (CaMV35s) is extensively used in genetically modified crops for human and animal consumption. Horizontal gene transfer is attracting particular attention, in light of experimental reports, showing the presence of dietary DNA into animal tissues. Health implications may derive from possible activities of the heterologous promoter in mammalian cells after integration in the host genome. To evaluate this hypothesis, in vivo and in vitro experiments were performed using GFP as reporter gene. Recombinant plasmid DNA was fed to Balb/c mice and searched in several tissues by PCR amplification. The activity of the plant virus promoter was assessed by RT-PCR and fluorescence microscopy after liposome-mediated transfection of murine gonadic cells. Obtained data did not highlight evidences of dietary DNA transfer in mice. No CaMV35s transcriptional activity was detected in this experimental model. These findings emphasize the need for further studies and standardized methods.

Cauliflower mosaic virus (CaMV) Biology, Management, and Relevance to GM Plant Detection for Sustainable Organic Agriculture

“…Sequence overlap exists between P35S and the coding sequences of one CaMV gene, gene VI, also known as P6 (Figure 1), indicating the potential for virus protein expression in humans (Podevin and Du Jardin, 2012). Another concern is the horizontal gene transfer risk with DNA recombination that can potentially occur between P35S and human genes, along with the potential for P35S to facilitate expression of human genes (Chiter et al, 2000;Morel and Tepfer, 2000;Nielsen and Townsend, 2004;Paparini and Romano-Spica, 2006;Bawa and Anilakumar, 2012). In two studies that have attempted to address these concerns, no evidence was observed for the activity of the P35S promoter in mammalian cells (Vlasák et al, 2003;Paparini and Romano-Spica, 2006).…”

“…Another concern is the horizontal gene transfer risk with DNA recombination that can potentially occur between P35S and human genes, along with the potential for P35S to facilitate expression of human genes (Chiter et al, 2000;Morel and Tepfer, 2000;Nielsen and Townsend, 2004;Paparini and Romano-Spica, 2006;Bawa and Anilakumar, 2012). In two studies that have attempted to address these concerns, no evidence was observed for the activity of the P35S promoter in mammalian cells (Vlasák et al, 2003;Paparini and Romano-Spica, 2006). In terms of the potential for viruses to recombine with and acquire genes from transgenic plants (i.e., horizontal gene transfer from transgenic plants to a virus), earlier studies of CaMV have demonstrated that this is possible (Schoelz and Wintermantel, 1993;Wintermantel and Schoelz, 1996), but only under very specific conditions, such as strong selection pressure in the laboratory (Wintermantel and Schoelz, 1996).…”

Safe use of Cry genes in genetically modified crops

“…No disease or recombination with human viruses has ever been reported irrespective of the fact that humans have been ingesting high levels of CaMV and its 35S promoter (Paparini and Romano-Spica 2004). Recent studies conducted using mice as an experimental animal were unable to detect DNA transfer as well as transcriptional activity of the CaMV35S quantified through realtime PCR (Paparini and Romano-Spica 2006).…”

Biosafety Risk of Genetically Modified Crops Containing Cry Genes

“…In mammalian cells, transient expression of the transgenes transcribed by the CaMV35S promoter may possibly let the genes controlled by 35S promoter to express (Tepfer et al 2004). Contrary to this hypothesis, recent studies conducted using mice as an experimental animal, were unable to detect DNA transfer as well as transcriptional activity of the CaMV35S quantified through real time PCR (Paparini and Romano-Spica 2006). This area of research needs further explorations (Dona and Arvanitoyannis 2009).…”