Abstract
Genetic modification offers alternative strategies to traditional animal breeding. However, the food safety of genetically modified (GM) animals has attracted increasing levels of concern. In this study, we produced GM sheep overexpressing TLR4, and the transgene-positive offsprings (F1) were confirmed using the polymerase chain reaction (PCR) and Southern blot. The expression of TLR4 was 2.5-fold compared with that of the wild-type (WT) sheep samples. During the 90-day safety study, Sprague-Dawley rats were fed with three different dietary concentrations (3.75%, 7.5%, and 15% wt/wt) of GM sheep meat, WT sheep meat or a commercial diet (CD). Blood samples from the rats were collected and analyzed for hematological and biochemical parameters, and then compared with hematological and biochemical reference ranges. Despite a few significant differences among the three groups in some parameters, all other values remained within the normal reference intervals and thus were not considered to be affected by the treatment. No adverse diet-related differences in body weights or relative organ weights were observed. Furthermore, no differences were observed in the gross necropsy findings or microscopic pathology of the rats whose diets contained the GM sheep meat compared with rats whose diets contained the WT sheep meat. Therefore, the present 90-day rat feeding study suggested that the meat of GM sheep overexpressing TLR4 had no adverse effect on Sprague-Dawley rats in comparison with WT sheep meat. These results provide valuable information regarding the safety assessment of meat derived from GM animals.
Highlights
The first genetically modified (GM) animal was reported in 1985 [1]
GM sheep expressing high levels of circulating growth hormones were produced by microinjection
The linear fragment containing the sheep TLR4 gene was microinjected into the pronuclei (Fig 1A)
Summary
Transgenic techniques have been applied to produce GM animals with varying degrees of success. GM sheep expressing high levels of circulating growth hormones were produced by microinjection. Toxicology Study of Meat of TLR4 Transgenic Sheep of ovine metallothionein-ovine growth hormone fusion genes [2]. The insulinlike growth factor 1 and BChE gene were transferred to the sheep to improve their wool production and to protect against chemical agents, respectively [3, 4]. In addition to improving farm animal productivity and producing foreign protein as GM animal bioreactors, these transgenic techniques can be used to improve the health status and disease resistance of the animals more widely. GM sheep that expressed the visna virus envelope gene could be genetically resistant to infection from lentiviral pathogens (visna virus) [8]
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