Colostrum quality is a vital factor in mortality and growth performance for piglets. Lactoferrin is an immuno-active milk protein that contributes to the formation of a protective layer above intestinal mucosa, possesses the antibacterial and antiviral activities that are favorable for piglet development. However, there is a notable reduction in lactoferrin in sow milk during lactation after the first few days, which causes many piglets to fail to ingest enough colostrum thereby leading to an increase in piglet mortality. In this study, we successfully constructed genome-edited Large-White pigs with marker-free site-specific knock-in of lactoferrin gene in the 3′-end of Casein alpha-s1 via CRISPR/Cas9 mediated homologous recombination. Thus, the lactoferrin protein can be expressed in the mammary gland in the control of Casein alpha-s1 promoter. As expected, the lactoferrin protein in genetically modified pigs sustained high expression in both colostrum and milk when compared with wild-type pigs. Moreover, the bacterial plate assay indicated that the milk from genetically modified pigs showed bacteriostatic effects when compared with control pigs. Taken together, our study demonstrated that the milk from genetically modified pigs had antibacterial activity which may reduce the costs of veterinary drug and improve the surviving rate of piglets, which is promising for pig breeding.

中文翻译：

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使用CRISPR / Cas9技术通过猪中乳铁蛋白基因的位点特异性敲入提高母乳的抗菌活性

初乳质量是仔猪死亡率和生长性能的重要因素。乳铁蛋白是一种免疫活性的乳蛋白，有助于在肠粘膜上方形成保护层，并具有有利于仔猪发育的抗菌和抗病毒活性。然而，头几天后泌乳期间母猪乳汁中的乳铁蛋白明显减少，这导致许多仔猪无法摄取足够的初乳，从而导致仔猪死亡率增加。在这项研究中，我们成功地构建了基因组编辑的大白猪，通过CRISPR / Cas9介导的同源重组，在酪蛋白α-s1的3'端具有无标记的乳铁蛋白基因位点特异性敲入。因此，乳铁蛋白蛋白可以在酪蛋白α-s1启动子的控制下在乳腺中表达。不出所料，与野生型猪相比，转基因猪中的乳铁蛋白蛋白在初乳和牛奶中均持续高表达。此外，细菌平板分析表明，与对照猪相比，转基因猪的乳汁具有抑菌作用。综上所述，我们的研究表明，转基因猪的乳汁具有抗菌活性，可降低兽药成本并提高仔猪成活率，这对猪的育种很有希望。