Reversion of neurovirulence and in vitro phenotype of neural cell-adapted canine distemper virus after passage in non-neural cells.

The stability of neurovirulence and in vitro phenotypes of canine distemper viruses adapted to neural cells was examined. Neurovirulence was estimated by the morbidity, mortality, and histopathological changes in the central nervous system of mice. After a single passage of the adapted viruses in Vero cells in which the unadapted virus had been passed, the neurovirulence of glioblastoma-adapted and oligodendroglioma-adapted viruses reverted completely to that of the unadapted virus. However, the neurovirulence of a neuroblastoma-adapted virus reverted partially. In vitro phenotypes such as the two-dimensional electrophoretic patterns of viral proteins and the cross-neutralization patterns also reverted to those of the unadapted virus. However, plaque sizes remained similar to those of the viruses adapted to neural cells.