Defective Interfering Particles of Fixed Rabies Viruses: Lack of Correlation with Attenuation or Auto-interference in Mice

Six different fixed strains of rabies virus were analysed for their capacity to produce defective particles following acute infection of BHK-21 cells. Five of the six strains produced one or more defective particle populations with strain-specific sedimentation properties, particle length and abbreviated RNA genome size. These defective particles varied in their capacity to interfere with replication of standard rabies virus in cell culture. Each virus strain characteristically either killed adult mice according to a normal dose-response pattern or to an auto-interference type of pattern, or failed to kill mice. Different strains also varied in their capacity to induce a cytopathic effect in cell culture. However, there was no apparent correlation between the presence of defective particles and the pathogenic potential of rabies virus in mice or in cell culture.