ALTERATION OF THE ACTIN-BASED CYTOSKELETON BY RABIES VIRUS

We investigated the effect of rabies virus infection on the actin cyto skeleton using various techniques. Confocal microscopic examination of rabies virus-infected neuroblastoma cells at late stages of infection revealed a dramatic decrease in F-actin staining. The results of a fl uorimetric assay with pyrenylated actin indicated that purified rabies virus nucleocapsid has no direct action on the kinetics of actin poly merization and only a weak effect on the final extent of polymerizatio n. Videomicroscopy experiments with purified components showed that ra bies virus nucleocapsid inhibits the actin-bundling effect induced by dephospho-synapsin I, a neuron-specific protein which is known to exer t a control on the actin-based cytoskeleton. Thus, the observed decrea se in F-actin staining in infected cells might be ascribed to an indir ect action of rabies nucleocapsid on the effects of actin-binding prot eins such as synapsin I.