Preservation of Alfalfa mosaic virus by freezing and freeze-drying and similarities to Cucumoviruses

摘要

Alfalfa mosaic virus (AMV) belongs to the genus Alfamovirus of the family Bromoviridae, for which the virions are stabilized by dominant protein-RNA interactions. The infectivity of purified AMV preparations stored frozen at -20°C decreased to 10-20%in 2 years. In addition, the virion peak profiles after sucrose density gradient centrifugation (SDGC) was reduced to a single, broad peak as a result of virus particle degradation, and the peaks for the extracted virion RNA decreased. However, additives such as 0.5% peptone or 2.5% sucrose were markedly protective such that infectivity and the SDGC profiles of the virus particles and virion RNA remained essentially unchanged after 5-8 years of freezing. Infectivity of the purified AMV decreased to c.50%, and virus particles deteriorated immediately after freeze-drying. The addition of 1.0-7.5% sucrose suppressed alterations in infectivity, particle morphology and virion RNA after freeze-drying and other preservation processes. The characteristics ofAMV preservation were similar to those reported in a previous study on cucumoviruses. Consequently, viruses belonging to the Bromoviridae may preserve well with sucrose in conjunction with freezing or freeze-drying.