ROLE OF DEFECTIVE INTERFERING PARTICLES OF SENDAI VIRUS IN PERSISTENT INFECTIONS

We show that mixed infection with standard virus and defective interfering (DI) particles of Sendai virus regularly leads to the survival of infected cells and to the establishment of long-term persistent infections. Three independent carrier cultures were established and all strongly resist challenge by Sendai virus, while remaining fully susceptible to challenge by an heterologous virus, vesicular stomatitis virus. Nearly 100% of the carrier cells show viral antigen. Intracellular viral nucleocapsids isolated from these carrier cultures contain small amounts of 50 S RNA and up to 100-fold greater amounts of smaller-sized DI RNAs at all times during long-term persistence in BHK 21 cells. These carriers shed only small amounts of immature virus and DI particles into the medium. These standard virions and DI particles are biologically inactive unless activated by trypsin treatment. © 1979.