Defective interfering particles of Sindbis virus: III. Intracellular viral RNA species in chick embryo cell cultures

Abstract

Serial undiluted passage of wild-type Sindbis virus (SV-W) in primary chick embryo cell cultures resulted in a cyclic variation in the yield of infectious virus. Cells infected with virus stocks (SV-CP) derived from such passage series directed significantly less viral RNA synthesis than cells infected with SV-W at the same multiplicity of infection (MOI) and produced particles (ϱ = 1.20 g/cc) capable of homologous interference. Cells infected with SV-CP stocks of increasing passage number contained, in addition to 22S dsRNA (found in SV-W infected cells), species of virus-specific dsRNA of decreasing molecular size. The rate of evolution to the smaller dsRNA species was considerably faster during serial undiluted passage of SV-W in BHK-21 cells than in chick cells. Cells infected with SV-CP stocks also contained a new species of ssRNA for each additional species of dsRNA produced suggesting that the two are functionally related.