1990 Volume 56 Issue 1 Pages 47-55
The infectivity of purified southern bean mosaic virus (SBMV) in 10mM sodium phosphate buffer, pH 7.0, decreased to 11% after freeze-drying. Such partially swollen virions were found to be markedly susceptible to RNase and sodium dodecyl sulfate (SDS). However, in the preparations supplemented with 0.5% lysine prior to freeze-drying the conformational changes of the virions were suppressed and the effect of RNase and SDS was well tolerated. On the other hand, there were little differences in infectivity of extracted RNA from virions between the preparations with or without lysine. It was suggested that the alterations of the conformation of the SBMV virions caused mainly the decrease of the infectivity of the virus preparations. During storage at 65C, the preparations of freeze-dried viruses lost their infectivity within one day and all the virions became markedly swollen. RNA extracted from such virions was degraded completely and did not display any infectivity. On the other hand, the virions of the preparations supplemented with 0.5% lysine retained their conformation and a high level of infectivity was maintained in both the preparations of virions and RNA extracted from the virions compared with the preparations without any additives. In the freeze-dried preparations of SBMV-RNA, lysine showed a protective effect during storage. Freeze-dried preparations of carnation mottle virus during storage at 65C showed a response similar to that of SBMV.