The BEVS uses Autographa californica multiple nucleopolyhedrovirus (AcMNPV) to infect Spodoptera frugiperda (Sf9) or Trichoplusia ni (Hi5) insect cells. The foreign gene replaces the polyhedrin (polh) gene, which is non-essential for virus replication but is expressed at extremely high levels (up to 50% of total cell protein) late in infection. BEVS supports post-translational modifications including glycosylation and is used to produce vaccines, virus-like particles, and complex proteins.