Serological behavior of cucumber mosaic virus (strain Y) and the virus protein.
Antisera with titers of 1/128 were obtained by injecting rabbits intravenously (iv) or intramuscularly (im) with purified cucumber mosaic virus (strain Y) (CMV-Y). Gel-diffusion tests with CMV-Y resulted in the formation of a curved band with the iv antisera and both a curved and a straight band with the im antisera. The curved band results from the combination of high molecular weight virus antigen with specific antibody, and the straight band originates from the combination of a product of virus degradation and its specific antibody. Crude sap from infected tobacco and protein obtained from CMV-Y by KCl degradation did not react with iv antiserum in gel-diffusion tests and formed only the straight band with im antiserum. Both CMV-Y and virus protein precipitated with im antiserum in tube precipitin tests, but no precipitation occurred when iv antiserum was tested with virus protein. However, virus protein possesses the antigenic determinants of CMV-Y, as shown by cross absorption in test tubes. The ability of the protein to bind antibodies specific for the curved band antigenic determinant of CMV-Y is reduced when the protein is precipitated by dialysis against water or used in intragel absorption tests, but its ability to bind straight band antibody is not affected. Exposure of CMV-Y to 37 degrees for 1 hour or to buffers other than 0.005 M borate, pH 9.0, such as 0.05 M borate, pH 9.0, and 0.05 M phosphate, pH 8.0, resulted in reduction of the major virus peak and the appearance of smaller nucleoprotein fragments (shown by density gradient centrifugation).
Scott
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Plant Virology Laboratory, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705 ,USA.