Effect of various additives on the preservation of southern bean mosaic virus.

Freezing for a duration of one hour followed by thawing prevented changes in the infectivity of a purified preparation of southern bean mosaic virus (SBMV) suspended in 10mM potassium phosphate buffer (P.B.), pH 7.0. Infectivity of purified SBMV decreased gradually during the storage under frozen conditions at -20C. However, the infectivity was maintained at a high level for 52 months by the addition of peptone or glycerol, etc. At -70C, the infectivity was maintained for a long period without any additives. The virions of purified SBMV freeze-dried without additives became swollen by rehydration with P.B., and their infectivity decreased to 16%. But, the changes in the conformation of SBMV virions due to freeze-drying could be significantly prevented by the addition of lysine. The protective effect of additives during preservation of freeze-dried preparations was assessed at 65C. The infectivity of freeze-dried preparations in P.B. disappeared in one day but it could be detected 7 days after preservation, when the virus was freeze-dried with lysine.