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Etiology

Properties of Asparagus Virus II, a New Member of the Ilarvirus Group. Ichiro Uyeda, Former graduate research assistant, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser 99350, Present address of senior author: Department of Botany, Faculty of Agriculture, Hokkaido University, Sapporo, Japan; Gaylord I. Mink, plant pathologist, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser 99350. Phytopathology 71:1264-1269. Accepted for publication 25 February 1981. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-1264.

A virus originally isolated from asparagus in Washington and provisionally designated asparagus virus C was found to be very similar, if not identical, to asparagus virus II (AV II) briefly described earlier in Germany. The virus was seed-transmitted but induced no visible symptoms in greenhouse-grown asparagus seedlings. Purified virus preparations separated into three major nucleoprotein (NP) components and occasionally a minor component on rate zonal sucrose density gradients. The major components, designated NP 1, NP 2, and NP 3, sedimented at 104S, 95S, and 90S, respectively. A minor component, NP 0, sedimented faster than NP 1 and appeared heterogeneous in quasi-equilibrium centrifugation. Maximum infectivity was obtained with the mixture NP 1 + NP 2 + NP 3; each component alone exhibited little or no infectivity. Quasi-isometric particles of NP 1, NP 2, and NP 3 had modal diameters of 32 nm, 28 nm, and 26 nm, respectively, and were serologically identical. Two types of particles were found with NP 0: monomer particles 34–36 nm in diameter and dimers of particles 28 nm in diameter. Two serotypes of AV II were found in Washington.