STUDIES ON THE SONIC TREATMENT OF TOBACCO
MOSAIC VIRUS*
BY GERALD OSTER
(From the Department of Animal and Plant Patlwlogy of The Rockefeller
Institute for Medical Research, Primaon, New Jersey)
Pxa~ 4
(Received for publication May 15t 1947)
INXRODUCTXOI~
Takahashi and Christensen (1) found that the juice of plants suffering from tobacco mosaic virus disease was rendered non-infectious when subjected to intense sonic vibrations. Stanley (2) found that the biological activity of purified tobacco mosaic virus is reduced by sonic treatment and demonstrated that the sound has little or no effect on the activity of the virus if cavitation, normally associated with strong vibrations in liquids, is supressed by a lowering of the atmospheric pressure above the liquid. Kauschc, Pfankuch, and Ruska
(3) found with the electron microscope that sonic treated tobacco mosaic virus samples contained more short rod-like particles than are observed in untreated samples. The sonic treatment apparently results in a breakage into shorter fragments of the long rod-like particles associated with the tobacco mosaic virus disease and offers a convenient method of studying the relation between the size of the particles and their biological activity.
In experiments described in this paper, samples of centrifugally purified tobacco mosaic virus were subjected to strong sound vibrations for varying lengths of time. The physicochcmical properties of the sonic treated material were determined and the material was tested for biological activity. The virus particles as well as the fragments produced by sonic treatment were made to aggregate end-to-end and the properties of the aggregates were studied.
~XPERIIaXI~TAL m~.~ODS Am) R~SWLTS
Sonic Trea~raent.--Solutions of tobacco mosaic virus purified by differentialcentrifugation by the method of Stanley (4) were sonic treated in a magncto-striction sound generator operating at 9,000 cycles per second and producing approximately
I00 watts of acoustic energy. The apparatus (type R-22-I oscillatordeveloped by the Submarine Signal Co.) contains an effectivewater-cooling system so that at no time did the temperature rise above 17°C. The author is indebted to Dr. Thomas
Anderson of the Johnson Foundation for the use of this apparatus and also to Dr.

* Presented in part before the meetings of the Electron Microscope Society of
America, Pittsburgh, December 6, 1946, and the American Chemical Society,Atlantic
City, April 15, 1947.
89

The Journal of General Physiology

90

SONIC TREATMENT O]~ TOBACCO MOSAIC VIRUS

L. A. Chambers, formerly of the Johnson Foundation, for the use in preliminary experiments of the magneto-striction sonic generator developed by Chambers and
Flosdorf (5). It was found that both sonic generators, when tuned to maximum efficiency, delivered approximately equal energy to the liquid.
When the virus solutions were subjected to the sound vibrations, violent swirling was observed. The swirling is associated with cavitation in the liquid, which is caused by the strong sound vibrations. When cavitation is Suppressed by lowering the atmospheric pressure above the liquid, the swirling disappears.
Stream Birefringence and Viscosity.--The stream birefringence of the solutions of purified tobacco mosaic virus was observed by inverting a test tube of the material

0.16~
0.14}--

f

0.12 0.10

-

0.08

-

m i 0.06 0104

--

0.02I

Gm,/lO0 ,cc.

0.3

0.4

T~.xT-FI¢. 1. Specific viscosity as a function of concentration for purified tobacco mosaic virus sonic treated for 0, 2, 8, 16, 32, and 64 minutes. between crossed polaroids. It was found that the intensity of stream birefringence decreased roughly exponentially with time of sonic treatment.
The viscosities of solutions of tobacco mosaic virus also decrease as sonic treatment proceeds. Solutions of centrifugally purified virus (3.28 mg./cc, in 0.1 ~ phosphate buffer at pH 7.0) were subjected to sonic treatment for 2, 8, 16, 32, and 64 minutes.
Viscosity