Polyclonal antibody(IgG) was isolated from antiserum against the recombinant coat proitein(CP) of PLRV by the treatment of saturated ammmonium sulfate,then crude IgG was purified with protein G affinity chromatography column.High purity IgG was achieved and labelled with alkaline phosphatase by one-step method of glutaraldehyde,and enzyme-conjugated IgG(IgG-AP) was obtained.When PLRV-infected potato leaf was detected by DAS-ELISA procedure using the prepared IgG and IgG-AP,positive reaction was observed,and there was no positive reaction in the detection of healthy leaf.The result indicated that the IgG against the recombinant CP and the resulting IgG-AP were successfully used in DAS-ELISA detection of potato leafroll virus.

Using plasmid pBAD-LRCP-126 as template,specific band of PLRV deletion mutation CP gene was obtained by PCR amplification.The target DNA fragment was recovered and ligated into the initial expression vector pYES2.1/V5-His/-TOPO.The recombinant plasmid was transformed into E.coli TOP10F′.Single digestion of restriction endonuclease and DNA sequencing confirmed the accuracy of the CP gene expression vector named pYES-LRCP-126.The engineered strain INVScl(pYES-LRCP-126) was induced with 2% galactose at 30 ℃ for 16 hours,and specific 23 kDa protein band was found in the SDS-PAGE pattern.Deletion mutation CP gene of PLRV was expressed correctly in Saccharomyces cerevisiae.