ABSTRACT
Defective interfering (DI) particles of vesicular stomatitis virus (VSV) are generated and enriched during consecutive undiluted passages of the virus. Their name derives from their inability to produce progeny in the absence of standard VSV and from their ability to reduce the yield of B particles in mixed infections with VSV. DI particles contain the same viral proteins in approximately the same relative amounts as are found in the standard infectious virus. They differ from VSV in that their genomic RNA is smaller, ranging from one tenth to one half the size of VSV genomic RNA. The implications of the RNA products from 5' end DI particles remain to be explored. In vitro production of a small RNA made by the 5' end DI particles may result from an abortive replication or transcription process. The ability of DI particle to direct the synthesis of viral proteins may potentiate an immune response in animals infected with helper and this DI particle.
