MACROMOLECULES CAN PENETRATE THE HOST-CELL MEMBRANE DURING THE EARLY PERIOD OF INCUBATION WITH HVJ (SENDAI VIRUS)

Fragment A of diphtheria toxin (MW 22,000) can penetrate the cell membrane during incubation with uv-inactivated HVJ. The amount of fragment A transfered to cells depends on the concentrations of both fragment A and HVJ. The penetration occurs most effectively during the early period of incubation at 37° (within 7 min) and the enhanced permeability of the cell membrane to macromolecules persists for at least 15 min at 37°. When uv-inactivated HVJ is adsorbed to erythrocyte ghosts containing fragment A, the HVJ virions released from the ghosts contain fragment A. These findings suggest that both the cell membrane and viral envelope become disordered during envelope-cell fusion. © 1979.