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An Improved Immunodiffusion Test for the Detection of Intact Cucumber Mosaic Virus in Crude Tobacco Sap. I. B. Ahmad, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; H. A. Scott, Department of Plant Pathology, University of Arkansas, Fayetteville 72701. Phytopathology 74:1097-1100. Accepted for publication 8 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1097.

An improved immunodiffusion test for the detection and serological differentiation of intact capsids of cucumber mosaic virus (CMV) in crude tobacco sap was developed. The immunodiffusion medium was prepared by melting 0.8 g of agarose in 100 ml of 0.1 M borate-0.05 M EDTA buffer, pH 9.0, containing 0.5% Triton X-100 and 0.01 M sodium thioglycolate. Sap from leaves of CMV-infected Nicotiana tabacum ' NC 95' or N. rustica was extracted with a leaf press 6- 10 days after inoculation. Test antigens consisted of 200 μl of sap mixed with 50 μl of 0.1 M borate-0.05 M EDTA buffer, pH 9.0, containing 15 mg of bentonite per milliliter and 1% formalin. Fifteen isolates of CMV produced intact capsid precipitin bands when tested by this method.