Component of the polyhedra envelope. Plays an essential role in the budded virus production. Present in both the budded virus (BV) and the occluded virus (OV). The occluded form allows the virus to be transmitted from insect to insect through ingestion of contaminated food while the budded form is responsible for the dissemination of infection throughout the insect host. Initially termed ODV-18 since it was found only in occluded viruses. New approaches also found the protein in budded virus. It has therefore been renamed to E18.