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Influence of Host and Seasonal Variation on the Components of Tobacco Ringspot Virus. J. L. Ladipo, Former Graduate Student, Department of Plant Pathology, University of Wisconsin, Madison 53706; G. A. de Zoeten, Associate Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 62:195-201. Accepted for publication 1 September 1971. DOI: 10.1094/Phyto-62-195.

When purified preparations of tobacco ringspot virus were centrifuged for 2.5 hr on buffered sucrose density gradients, each separated into four, three, or two components depending on the host in which the virus was increased and the season of the year when the host plant was infected. These components were designated 1, 2, 3, and 4 from top to bottom. Within a single season of the year, the type and the relative amounts of the components were determined by the five hosts used. The bulk of the infectivity was associated with component 3, and component 1 was not infectious. Unfractionated virus preparations were more infectious than component 3 when they were both diluted to the same A₂₆₀ reading.