The C-termini of the baculovirus infectivity factors 1 and 2 mediate ODV oral infectivity by facilitating the binding of PIF0 and PIF8 to the core of the entry complex.

Oral infection of caterpillars by baculoviruses is initiated by occlusion-derived virus particles (ODVs) that infect midgut epithelium cells. The ODV envelope therefore contains at least ten different proteins, which are called infectivity factors (PIFs). Nine of these PIFs form the so-called ODV entry complex that consists of a stable core formed by PIF1, 2, 3 and 4, to which the other PIFs [PIF0, 6, 7, 8 and 9 ()] bind with lower affinity.