Abstract
Infectivity of the purified preparations of cucumber mosaic virus (CMV) to Vigna sinensis Endle cv. Kurodane-Sanjaku remained unchanged during preservation for at least 30 months in 5 mM borate buffer, pH 8.6, at -20 C or -70 C. CMV in crude extract preparations in 50 mM borate buffer, pH 8.5 added with 5% sucrose or 1% Na-glutamate maintained a high infectivity for at least 37 months at -20 C. Purified CMV added with 0.025-0.05% NaN3 lost its infectivity during the storage of 2-12 months at 4 C. Addition of 0.01% dithiothreitol or 0.1% 2-mercaptoethanol had no significant effects on preservation of the virus infectivity. Purified virus preparations added with an equal volume of glycerol maintained considerably their infectivity for about 30 months at -20 C.
Repetition of freezing and thawing applied to purified CMV preparations or crude extracts of CMV-infected tobacco leaves did not alter the virus infectivity. By freeze-drying, the virus infectivity in crude extracts was immediately reduced to the range of 21 to 73% of its original infectivty, whereas it was almost unaffected by the treatment in purified preparations. The loss of the virus infectivity in the crude extracts due to freeze-drying could be prevented by the addition of 0.3% polypeptone, 1% Na-glutamate, 5% sucrose or 1% Na-glutamate plus 5% sucrose. In such preparations the virus infectivity could be maintained for 25 months even at 35 C. Freeze-dried preparations of purified virus maintained its original infectivity for at least 30 months upon storage at 4 C, -20 C, or -70 C.
