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Composition of Northern Cereal Mosaic Virus and its Detection by Enzyme-Linked Immunosorbent Assay with Anti-Nucleocapsid Serum. Y. Shirako, Faculty of Agriculture, Tohoku University, Sendai 980, Japan; Y. Ehara, Faculty of Agriculture, Tohoku University, Sendai 980, Japan. Phytopathology 75:453-457. Accepted for publication 9 November 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-453.

Nucleocapsids (Nc) of northern cereal mosaic virus (NCMV), a plant rhabdovirus, were isolated directly from infected wheat leaves by including Triton X-100 before the first high-speed centrifugation, which was followed by sucrose density gradient centrifugation and CsCl equilibrium density gradient centrifugation. Purified Nc had a tubular structure with a diameter of 28 nm and a pitch of 5.5 nm with uranyl acetate staining. Gel electrophoretic analysis revealed that Nc consisted of N protein with MW 47 x 103 daltons and an RNA with MW 3.5 x 106 daltons, whereas intact virions contained in addition two major and one minor polypeptide with MW 63 x 103, 19 x 103, and 88 x 103 daltons, which probably correspond to G, M, and L proteins, respectively. Antiserum produced against purified Nc had a titer of 1/1,024 determined with Ouchterlony gel double diffusion tests. With the enzyme-linked immunosorbent assay, purified Nc was detectable at a concentration as low as 2 x 10- 5 A260 nm units per milliliter, which corresponds to approximately 10 ng/ml. In vivo-Nc was detected from the homogenates of fresh, frozen, and freeze-dried diseased leaves diluted up to 10- 5 and also from the homogenate of a single viruliferous planthopper, Laodelphax striatellus.

Additional keywords: insect-borne virus, serological diagnosis, virion composition.