Production of a chicken resistant strain using antiviral Mx gene

我们已经报道了鸡抗病毒Mx基因的多态性，631位氨基酸的特异性替换对应着不同的抗病毒活性。也就是说，鸡Mx基因对流感病毒和水泡性口炎病毒的感染实验中位于631位的Ash是一个抗性性状，而在Ser.本研究以一滴血中提取的基因组DNA为模板，建立了一种利用限制性内切酶长度片段多态技术(PCR-RLFP)对鸡的Mx基因进行遗传诊断的简便方法。对500个商品鸡品种的检测结果表明，约50%的鸡品种携带抗性Mx基因，约50%的鸡品种携带敏感的Mx基因。此外，最后一个外显子的核苷酸序列分析表明，只有一只丛林鸡(红色丛林鸡)的Mx基因编码抗病类型，而所有其他丛林鸡(红、灰、绿丛林鸡)的Mx基因编码敏感类型的Ser。此外，另一种鸟类(雀形目)，如日本鹌鹑和火鸡携带敏感类型的丝氨酸。因此，从这些结果来看，敏感的Mx基因可能是鸡的祖先类型，而抗性的Mx基因可能随着鸡的驯化而出现。

We have reported the polymorphism of antiviral Mx gene in the chicken, and that the specific amino acid substitution at position 631 corresponds to the differential antiviral activity. Namely, the chicken Mx gene is a resistant character in the case of Ash at the position 631 against the infectious experiment using influenza virus and vesicular stomatitis virus, and is sensitive in the case of Ser. In this study, we have established the simple method of genetic diagnosis whether each chicken carry the resistant or sensitive Mx gene by PCR-RLFP (restriction enzyme length fragment polymorphism) using genomic DNA extracted from one-drop of blood. As the result of determination in 500 indivuduals of the chicken commercial breeds, about 50% of them carry the resistant Mx gene and also about 50% have the sensitive Mx gene. In addition, it was demonstrated by the nucleotide sequence analysis of last exon that the Mx gene from only a jungle fowl (red jungle fowl) coded the resistant type of Ash, but those from the all other jungle fowl (red, gray and green jungle fowl) did the sensitive type of Ser. Furthermore, another birds (Galliformes) such as Japanese quail and and turkey carry the sensitive type of Ser. Therefore, from these results, the sensitive Mx gene was considered as the ancestor type in the bird, and the resistant Mx gene might appear with domestication of chicken.