Aggregation of Purified Tobacco Mosaic Virus

Abstract

WHEN we found that the infectivity and filter-ability of preparations of-tobacco mosaic virus Were reduced and the anisotropy of flow Was increased by chemical methods of isolation, we suggested that linear aggregation had taken place^1'2. This is now confirmed by Loring, Lauffer and Stanley, but they claim that unaggregated preparations can be made by the use of a high-speed centrifuge. We found that sedimenting the virus increased anisotropy of flow, but We made no measurements of the effect on infectivity or filterability. It was suggested by analogy with the chemically prepared virus that this effect was also a result of aggregation. There is no necessary contradiction between our observations and those of the American Workers. We centrifuged for 3 hours at 25-30° C, whereas they used a more efficient centrifuge running at 5° C. ; furthermore, their measurements of anisotropy of flow were made at very much higher rates of shear³ than were ours. A lengthening of the virus rod would be expected to increase the readiness with which anisotropy of flow would be demonstrated rather than the total amount shown, and the changes which We have claimed might Well be undetectable by their method.