| A new viral disease whose pathogen was goose paramyxovirus has outbroken in many areas of china since 1997. Characteristic of the disease is the lesion mainly in the digestive, respiratory tract and high mortality, causes serious loss in goose breeding industry. The routine diagnostic methods for GPMV were the Agargel precipitin assays (AP), Serum-neutralization test (NT) , have been established. These methods have played important role in control of GPMV, but which has lower sensitivity and take longer time. These methods have not been suitable for the needs of efficient control of GPMV.The study is that the recombinant expression plasmid pGEX-6P-NP was transformed into BL21(DE3)pLysS. The recombinant NP protein was expressed in E.coli and purified. An indirect ELISA was developed with the purified protein as coating antigen, goose serum which was made by inactivated vaccine as antibody and HRP conjugated rabbit anti-goose IgG as anti-antibody. The optimal conditions were that antigen is coated at 4℃ overnight and its concentration is 54μg/ml, serm sample (1:800) and HRP conjugated rabbit anti-goose IgG(1:1500) are incuabtaed at 37℃ for 60 min, the substrate of ELISA is incuabated at 37℃ for 20min. Every condition and parameter is optimized, then settle a good foundation for standardizing diagnostic kit. It is testified that the coating antigen only react with GPMV antibody by crossing assay and blockage assay. The negative result is shown with serums from healthy goose and SPF chicken. The reaction between antigen and positive serum can blocked by GPMV in chick embryo which proves specificity of the antigen is faithful. The developed method has good specificity, sensitivity and repeatability that can be used as epidemiologic survey and detection of antibody after being immunized by GPMV inactivated vaccine.
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