Vesicular stomatitis virus defective interfering particle containing a muted internal leader RNA gene.

Abstract

The RNA of a unique long defective interfering particle (DI-LT2) derived from the heat-resistant strain of vesicular stomatitis (VSV) contains 70 nucleotides at its 3'' end that are complementary to the 5'' end of the VSV RNA. Following this region of terminal complementarity, there is a precise copy of the 3'' end of the nondefective VSV RNA. The sequence homology between the DI-LT2 RNA and the 3'' end of VSV RNA extends for at least 60 bases and probably for most of the length of the DI-LT2 RNA. The DI-LT2 particle is capable of transcription in vitro but produces only a short RNA [defective interfering (DI) particle product], which is encoded by the extreme 3'' terminus of the DI RNA. Neither leader RNA nor capped VSV mRNA are synthesized by DI-LT2, although competent templates for these are present. The 3''-terminal initiation is apparently a prerequisite of the production of competent transcripts. The sequence coding for leader RNA is apparently not, by itself, sufficient for initation. A model for the origin of this DI particle, involving specific termination and resumption of replication is proposed. This model is similar to one previously described for another class of DI particle RNA.