Abstract: Avian leukosis virus subgroup J (ALV-J) is widespread in China,causes great damage to China's poultry industry.There is no effective methods of prevention and therapy of avian leukosis,but purification control. So,researching a low-cost,easy-to-promote way for specific detection of ALV-J is important.In this study,the ALV-J ZH-08 strain was inoculated into DF1 cells,an ALV-J gp85 DNA fragment of 941 bp was amplified from infected cells and inserted into pET32a(+) plasmid at the location between restriction endonucleases Nco Ⅰ and Hind Ⅲ sites. The recombinant plasmid pET32a-gp85 was transformed into E coli. BL21 for gp85 gene expression,and separated by using SDS-PAGE. Target protein was isolated by cutting the gel slices that contain the right band. With purified recombinant gp85 protein as antigen,mono-specific serum against gp85 would be produced afterward.The results demonstrated that good antigenic protein was made,and high titer serum (above 1.024×10⁵) was prepared by this method. It showed a reference for preparation of mono-specific antiserum,laid the basis for gp85 protein researching and ALV-J specific detection method establishment.This study has high value for ALV-J purification.

Key words: subgroup J avian leukosis virus; mono-specific serum; gp85 gene; protein expression