Neuroinvasion by herpes simplex virus. An in vitro model for characterization of neurovirulent strains.

A cell culture technique with rat dorsal root ganglion neurons cultured in a two-chamber system allowing exposure of neuritic extensions or neuronal cell soma to herpes simplex virus (HSV) infection was exploited for studies of viral neuroinvasiveness. Four groups of HSV strains were investigated. Type 1 strains were isolated from cases of either encephalitis or mucocutaneous infections and type 2 strains were from cases of meningitis or genital infections. The neuroinvasiveness of the type 1 encephalitis strains was significantly greater than the neuroinvasiveness calculated for the type 1 strains of cutaneous origin or for either of the type 2 strains. From our evaluation of the rates of neuritic uptake and axonal transport and the rate of replication in dorsal root ganglion cells and skin fibroblasts, we concluded that the differences observed in neuroinvasiveness probably reflected differences in early virus-nerve cell interactions, i.e. virus attachment and fusion with the neuritic plasma membrane.