Production of a chicken resistant strain using antiviral Mx gene

我们报道了鸡抗病毒Mx基因的多态性，其第631位的特异性氨基酸替换对应于不同的抗病毒活性。即，鸡Mx基因在631位的Ash的情况下是对使用流感病毒和水泡性口炎病毒的感染实验的抗性特征，而在Ser的情况下是敏感的。建立了用PCR-RLFP技术进行鸡Mx基因抗性或敏感性遗传诊断的简便方法（限制性内切酶长度片段多态性）使用从一滴血中提取的基因组DNA。对500个鸡种的检测结果表明，约50%的鸡种携带Mx抗性基因，也约50%的鸡种携带Mx敏感基因。另外，通过对Mx基因最后一个外显子的核苷酸序列分析，证明Mx基因是一种原鸡的特有基因，（红色原鸡）编码的抵抗类型的灰，但那些从所有其他原鸡（红、灰、绿色原鸡）对敏感型的丝氨酸蛋白酶（Ser.）鸡形目（Galliformes）如日本鹌鹑和火鸡携带敏感型Ser。因此，从这些结果来看，敏感型Mx基因被认为是鸟类的祖先型，Mx抗性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.