Abstract: To develop a “semi-quantitative RUN test” method to detect antibody against Newcastle disease virus, Tri-sodium citrate with aqueous gold chloride were warmed up and mixed to make gold sol. The 20nm-diameter colloidal gold was used to mark NDV antigen and the colloidal gold strip was prepared for semiquantitative test of antibody against NDV. 60 samples were tested by the colloidal gold strip. The coincidence between the colloidal gold strip and HI was 93.8%. The least test level of the strip was 4log2 detected by HI experiment, and it didn't exist crossreaction with other serums against corresponding virus . The strip was still effectual after storing three months at room temperature . Colloidal gold kit is a rapid method in clinic practice and could be used in surveillance of antibody against NDV.

Key words: Newcastle disease, colloidal gold, antibody, strip