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，并且在631位的特定氨基酸替换对应了抗病毒活性的差异。即鸡Mx基因在631位的Ash对流感病毒和水疱性口炎病毒的感染实验中是抗性性状，在Ser的感染实验中是敏感性状。本研究利用一滴血基因组DNA，建立了用PCR-RLFP（限制性内切酶长度片段多态性）技术对每只鸡是否携带耐药或敏感Mx基因进行遗传诊断的简便方法。对500只商品鸡进行检测，其中约50%的鸡携带耐药基因，约50%的鸡携带敏感基因。此外，最后外显子的核苷酸序列分析表明，只有一种丛林鸡（红色丛林鸡）的Mx基因编码了抗性型，而其他所有丛林鸡（红色、灰色和绿色丛林鸡）的Mx基因编码了敏感型。此外，其他鸟类（雁形目），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基因可能是禽类的祖先型，而耐药型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.