Elementary aspects of autointerference and the replication of defective interfering virus particles

Despite differences in size, genetic content, and transcribing abilities, four types of defective interfering particles (DIs) interfered with the replication of the homologous (Indiana) helper virus to the same extent. Similarly, no significant difference was observed when the abilities of the DIs to be replicated with the Indiana helper were compared. However, when the New Jersey (Hazlehurst) strain was employed as a helper virus, significant differences in DI replication were observed. Three of the four particles were replicated as well as or better than in the completely homologous system; the fourth was replicated only to a very limited extent. In none of the infections with the Hazlehurst strain of VSV(NJ) was there detectable interference, which was measured as a reduction in the number of progeny infectious particles. Thus, depending on the helper virus used, these particles can be classified as defective interfering (DI) or defective noninterfering (DNI) particles. This curious result was obtained not only with the Hazlehurst strain but also with the Prevec strain of VSV(NJ).