Susceptibility of various cell lines to virulent and attenuated strains of pseudorabies virus.

Various cell lines were infected with virulent and attenuated strains of pseudorabies virus (PRV). According to the type of the cytopathic effect (CPE), the cells could be divided into 3 groups: cells in which all strains formed syncytia; cells in which all strains caused rounding of cells; and cells in which virulent strains caused syncytium formation while attenuated ones rounding of cells. Neither the form (fibroblastoid or epithelial) nor the origin of cells influenced the type of the CPE. L cells and some cell lines derived from human tissue proved to be less sensitive to PRV than other cells. In certain human cells (e.g. HeLa and D6) virulent PRV strains propagated better than attenuated ones.