Safety Assessment of Genetically Engineered Foods

Abstract

Translation from original language as provided by authorWith the widespread use of transgenic technology in breeding, animal bioreactor, and xenotransplantation, people pay more and more attention on biosafety issues including the impact of horizontal gene transfer or unintentional release of transgenes on biodiversity, the potential risk of gene modification on animal health, and food safety of genetically engineered (GE) animals. This study evaluated the environmental safety and heath status of GE dairy cows that were previously transformed with a human gene encoding lysozyme, lactoferrin, or alpha lactalbumin. It was also assessed that the impact of human lactoferrin (hLF) transgenic bovine milk on calves health. The environmental safety of GE dairy cows were assessed through the following protocols. 1) Detecting the transgenes in microbial DNA extracts of manure or soil by PCR or quantitative real-time PCR. The results were negative. 2) Studying the microbial communities in dairy cows gut or soil by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and 16S rDNA sequencing. The results showed that there was no significant different gut microflora between GE and non-GE dairy cows. And Firmicutes and Bacteroidetes were predominant microflora in both GE and non-GE dairy cows. Soil microflora were also similar among samples, and the soil bacteria belonged to four groups including Firmicutes, Bacteroidetes, Actinobacteria, and α-proteobacteria. 3) Analyzing nutrient element of dairy cows manure or soil by phsio-biochemical method. We found that the variation of nutrient element of manure or soil probably caused by animal-to-animal variation or soil spacial difference but not the transgenes. All of these results indicated that these GE dairy cows had no impact on environment. We also assessed the impact of exogenous genes on these GE dairy cows health by hematology, immunology, and metabonomics. Most values of hematology were normal either for GE dairy cows or control dairy cows. There was no significant difference between some abnomal values of GE dairy cows and that of control dairy cows. The data of immunology for foot and mouth disease were also normal, the values of O or Asia I type of antibody were less than 1:64 (standard established by Ministry of Agriculture of China). The result of metabonomics showed preliminarily that there was different metabolic level between different genotype dairy cows. It is necessary to develop more metabolic experiment to verify the impact of exogenous genes on dairy cow health. We concluded from these resuts that the trangenes probably had no harmful impact on the health of GE dairy cows. For assessing calves health, we weighted calves and sampled manure or blood of calves at 0, 15, 30, 45 days of feeding, respectively. Manure used for microflora analysis and bacteria culturing, blood used for hematology. The results showed that there was no significant difference of weight, gut microflora or cultured bacteria between T (feeing hLF fresh bovine milk)and C (feeding control fresh bovine milk). So transgenic hLF bovine milk probably had no harmful impact on calves