ABSTRACT
Undiluted passages of animal viruses in tissue cultures result in the generation of truncated particles which interfere with viral infection. This chapter suggests that the inhibition was due to a transmissible interfering agent which could have been either an incomplete form of vesicular stomatitis virus (VSV) or an interferon-like substance. The negative strand nature of VSV and defective interfering (DI)-particle RNAs was demonstrated by annealing the latter to cytoplasmic extracts of virus-infected cells. The availability of DI-particle RNAs of various sizes and improvements in the techniques of viral mRNA fractionations made it finally possible to determine the cistronic content of DI-particle RNAs experimentally. DI particles generated by New Jersey serotype of VSV have been isolated and mapped. Several isolates of the New Jersey serotype virion exhibited very limited homology among their RNAs, as discovered during the mapping of their respective DI-particle RNAs.
