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Cytofluorimetric Method for the Detection of the Cucumber Mosaic Virus. D. Iannelli, Chair of Immunology, School of Agriculture, University of Naples Federico II; M. Barba(2), L. D’Apice(3), G. Pasquini(4), R. Capparelli(5), L. Monti(6), G. Parrella(7), F. Scala(8), and C. Noviello(9). (2)(4)Experimental Institute of Plant Pathology, Rome; (3)(5)Chair of Immunology, School of Agriculture, University of Naples Federico II; (6)(7)Department of Agronomy and Plant Genetics, University of Naples Federico II; (8)(9)Institute of Plant Pathology, School of Agriculture, University of Naples Federico II. Phytopathology 86:959-965. Accepted for publication 20 May 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/Phyto-86-959.

This study describes a method for the detection of cucumber mosaic virus (CMV) by flow cytometry. Extracts from leaves of healthy and virus-infected plants were incubated with latex particles, washed, and then incubated in succession with rabbit anti-CMV antibodies and anti-rabbit immunoglobulin antibodies labeled with fluorescein. Adsorption of CMV virions on the latex particles allowed the virions to become visible to the laser of the cytometer. When the threshold value for virus detection was set at three times that of healthy controls, the detection limit of the cytofluorimetric method was 10 pg/ml of purified virions and that of the enzyme-linked immunosorbent assay (ELISA) was 2.5 ng/ml. The measuring range of the assay described here was 5 ng to 10 pg of purified virions and that of ELISA was 20 to 2.5 ng. The cytofluorimetric method detected the coat protein of CMV in the extract of two transgenic plants at a dilution of 10^-3, while ELISA detected the viral protein at a dilution of 5 × 10^-2. The assay was also used to detect plum pox potyvirus and potato virus Y, alone as well as concurrently with CMV.