马立克氏病病毒（MDV）B抗原基因的克隆及鉴定

CLONING AND IDENTIFICATION OF MDV B ANTIGEN GENE

将ＭＤＶＧＡ株ＢａｍＨＩ基因文库中含Ｉ３片段的质粒ｐＡＣＹＣ１８４和Ｋ３片段的质粒ｐＨＣ７９扩增。用碱裂解法抽提质粒后，利用相应的限制性内切酶切出目的基因片段，连接到合适的载体上，构建了完整的ＭＤＶＢ抗原基因克隆载体。通过内切酶分析、地高辛（ＤＩＧ）—探针原位杂交、ＤＮＡ序列测定，确认克隆的Ｂ抗原基因正确。

The gene, 3.9 kb in size, encoding MDV B antigen lies between I 3 and K 3 fragments in highly virulent strain GA BamH I liberary. After selection and amplification, the pACYC 184 I 3 and pHC 79 K 3 plasmids were extracted. The required fragments were selected with correspording restriction endonuclease and inserted into suitable cloning vector by two steps. Finally, the cloned B antigen gene was identified by restriction endonuclease analysis, DIG probe hybridization and DNA sequencing.