Induction of interferon in L cells by defective-interfering (DI) particles of vesicular stomatitis virus: Lack of correlation with content of [±] snapback RNA

Abstract

The ability of defective-interfering (DI) particles of vesicular stomatitis virus (VSV) to induce interferon was studied in relation to the amount of snapback [±] double-stranded sequences in their RNA. Five DI particles propagated in BHK-21 cells were analyzed: two DI particles generated by undiluted passages of cloned wild-type VSV (Indiana); two DI particles generated by serial undiluted passages of culture fluid from L cells persistently infected with VSV; and DI-011, a DI particle with [±] snapback RNA, which is known to be a potent inducer of interferon. Induction of interferon in L cells by these DI particles was not proportional to the amount of [±] sequences in their RNA. DI-011 (26 to 37% [±] RNA sequences) induced a significant amount of interferon at a multiplicity of infection of one DI particle per cell. In contrast, the two DI particles from wild-type VSV (43 to 54% [±] RNA sequences) were 20- to 30-fold less efficient inducers of interferon than DI-011. Furthermore, the two DI particles (1 to 4% [±] RNA sequences) generated from L cell carrier cultures were only slightly less efficient inducers of interferon than the wild-type DI particles. The data also indicate that a population of DI particles which contains [±] RNA is not selected in L cells persistently infected with VSV.