Baculovirus Replication: Glycosylation of Polypeptides Synthesized in Trichoplusia ni Nuclear Polyhedrosis Virus-infected Cells and the Effect of Tunicamycin

Abstract

Infected cell-specific polypeptides (ICSP) in T. ni nuclear polyhedrosis virus (MNPV)-infected Spodoptera frugiperda cells could be radiolabeled with various sugar precursors including mannose, N-acetyl glucosamine, N-acetyl mannosamine and glucose. Glycosylation occurred mainly late in infection. Eleven polypeptides were glycoslyated including the major envelope protein, the polyhedron protein (very late in infection) and a major low MW nonstructural polypeptide (als very late in infection). Tunicamycin inhibited T. ni MNPV replication and prevented the addition of N-acetyl glucosamine and, to a lesser extent, mannose to the appropriate proteins. This had the effect of enhancing the migration in sodium dodecyl sulfate-polyacrylamide gels of some glycopolypeptides but not that of the polyhedron protein. Tunicamycin prevented the envelopment of nucleocapsids both within the nucleus and at the plasma membrane. Polyhedron formation did occur in the presence of tunicamycin.