Abstract: Coat protein gene（cp）was amplified by RT-PCR from papaya leaves infected by Papaya ring spot virus and cloned to prokaryotic expression vector pET28b（+）. After identification by enzyme digestion and sequencing，the recombinant clone was transformed to Escherichia coli for protein expression. The fusion protein was highly expressed by groping the expressing host bacteria，concentration of IPTG and inducing time. SDS-PAGE indicated that the molecular weight of fusion protein highly expressed was 36.8 kD. The purified protein by Ni2+-NTA affinity chromatography was used as antigen to
immunize the healthy rabbit for antiserum preparation. Indirect-ELISA（ID-ELISA）assay showed the optimal titer of the antiserum was 1︰16 384. Western blot analysis confirmed that the antiserum reacted specially with CP protein of PRSV. ID-ELISA testing of a number of field samples demonstrated the sensitivity and specificity of the antiserum. The present study had paved a way to establish the methods of PRSV detection and the research protein function of PRSV.

Key words: papaya, Papaya ring spot virus, coat protein gene（cp）, prokaryotic expression, antiserum preparation