Functional Relationships between Virus-specific Products of Infection by Viruses of the Tobacco Rattle Type

Abstract

SUMMARY Preparations of nucleoproteins from stable variant infections of viruses of the tobacco rattle type were separated, by density gradient centrifugation, into' top' and' bottom' fractions containing predominantly' short' or' long' particles respectively. Comparisons of the products of infection when these fractions were used as inocula alone and mixed indicated that though lesion production and RNA replication were mediated by 'long' particles, the presence of' short' particles was nccessary for virus protein coat production. The coat-inducing function of' short' particles could also be used to stabilize RNA from homologous or closely related unstable variant infections. Inoculating systemic hosts with 'short' particle preparations together with phenol extracts from the unstable variant infections, resulted in stable variants similar to those from which the unstable variants were initially derived.