N-TERMINAL SEQUENCES FROM AUTOGRAPHA-CALIFORNICA NUCLEAR POLYHEDROSIS-VIRUS ENVELOPE PROTEINS ODV-E66 AND ODV-E25 ARE SUFFICIENT TO DIRECT REPORTER PROTEINS TO THE NUCLEAR-ENVELOPE, INTRANUCLEAR MICROVESICLES AND THE ENVELOPE OF OCCLUSION DERIVED VIRUS

Baculovirus occlusion-derived virus (ODV) derives its envelope from an intranuclear membrane source. N-terminal amino acid sequences of the Autographa californica nuclear polyhedrosis virus (AcMNPV) envelope pr oteins, ODV-E66 and ODV-E25 (23 and 24 amino acids, respectively) are highly hydrophobic. Recombinant viruses that express the two N-termina l amino acid sequences fused to green fluorescent protein (23GFP or 24 GFP) provided visual markers to follow protein transport and localizat ion within the nucleus during infection. Autoflourescence was first de tected along the cytoplasmic periphery of the nucleus and subsequently localized as foci to discrete locations within the nucleus. Immunoele ctron microscopy confirmed that these foci predominantly contained int ranuclear microvesicles and the reporter fusion proteins were also det ected in cytoplasmic membranes near the nucleus, and the outer and inn er nuclear membrane. Therefore, these defined hydrophobic domains are sufficient to direct native and fusion proteins to induced membrane mi crovesicles within a baculovirus-infected cell nucleus and the viral e nvelope. In addition, these data suggest that movement of these protei ns into the nuclear envelope may initiate through cytoplasmic membrane s, such as endoplasmic reticulum, and that transport into the nucleus may be mediated through the outer and inner nuclear membrane.