Immune sera and antiglycoprotein monoclonal antibodies inhibit in vitro cell-to-cell spread of pathogenic rabies viruses.

Although the cell-to-cell spread of many viruses in vitro is inhibited by antibody, the effect of antibody on such spread of rabies viruses is uncertain. Thus, we examined the effects of anti-rabies virus immune sera and monoclonal antibodies (MAbs) on the in vitro spread of pathogenic rabies viruses in neuronal and nonneuronal cells. Both anti-rabies virus immune sera and neutralizing antiglycoprotein MAbs inhibited the cell-to-cell spread of street rabies virus, challenge virus standard, and ERA rabies viruses in cultures of neuroblastoma cells and of nonneuronal BHK-21 and chicken embryo-related cells. Furthermore, the cell-to-cell spread of virus was inhibited by greater than or equal to 75% with less than 1 IU/ml of human antirabies immunoglobulin. Nonneutralizing antinucleocapsid MAbs did not inhibit viral spread. After the immune serum was removed from the monolayers, virus spread rapidly to uninfected cells. Thus, antibody controlled the cell-to-cell spread of the virus but did not eliminate it from the cultures. Because antibody was more effective in inhibiting viral spread in fibroblast and epithelioid cells than in neuroblastoma cells infected at a high multiplicity of infection, we suggest that the inhibition of viral cell-to-cell spread by antibody in vivo would more likely occur at an initial site of exposure and before nerves are infected.