Monoclonal antibodies (MAbs) directed against herpes simplex virus (HSV)-coded glycoproteins gB, gC, gD and gE were employed in a an in vitro model of neuroinvasiveness using sensory neurons from rat dorsal root ganglion (DRG) cells. The neurons were cultured in at two-chamber system allowing infection via the neuritic extensions exclusively. The effects of 30 MAbs on viral replication of the encephalitis-derived HSV-1 strain 2762 and its less neuroinvasive variant 2762p11 were assayed in this model. One MAb reactive with gD gave a nine-fold reduction of the virus yields of both strains. One MAb directed against gB gave an enhanced virus yield of strain 2762, but not of the 2762p11 variant. Another gB-reactive MAb decreased the virus yield of strain 2762p11, but not of 2762 after neuritic infection. The findings indicate that an alteration of gB has occurred during the passage of the strain 2762. Mutants of the same strain were derived by infecting hybridomas producing MAb reactive with gB, gC, gD and gE, respectively. The gB hybridoma mutant showed a significantly lower neuroinvasiveness in the DRG model, and was non-virulent after snout infection of mice. We suggest that the structure of gB of the strain 2762 is of importance for the neuroinvasiveness of this strain.