The envelope protein gp64 of the baculovirusAutographa californicanuclear polyhedrosis virus is essential for viral entry into insect cells, as the glycoprotein bothmediates pH-dependentmembrane fusionandbinds tohost cell receptors. Surface modification of baculovirus particles by genetic engineering of gp64 has been demonstrated by various strategies and thus has become an important and powerful tool in molecular biology.