Immunoelectron microscopic examination of Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus-infected Lymantria dispar cells: time course and localization of major polyhedron-associated proteins

Abstract

Immnnoelectron microscopy was employed to examine the temporal expression and localization of two proteins involved in baculovirus polyhedron assembly (polyhedrin and p 10) of Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV) in infected Lymantria dispar cells. In addition, the association of p 10 with the polyhedron envelope (PE) protein was studied. The major capsid protein (p39) was also examined to investigate the association of virion structural proteins with polyhedron formation. In infected cells, p39 did not show a concentrated association with any infected-cell structures other than nucleocapsids and appeared to be randomly distributed over the nucleocapsid surface. Likewise, polyhedrin showed no major concentrations outside of developing or mature polyhedra. The pl0 antibody cross-reacted with a protein associated with condensed chromosomes in uninfected cells. In infected cells, pl0 is a component of the body of fibrillar structures. The PE protein has been shown to accumulate around the periphery of fibrillar structures. Cells infected with a polyhedrin-minus virus expressing the fl-galactosidase gene under the control of the polyhedrin promoter were examined to determine whether the lack of polyhedra would influence the localization of major polyhedronassociated viral proteins. High concentrations of PE protein accumulating on the periphery of fibrillar structures appeared to be the major difference from wild-type virus-infected cells. The fl-galactosidase protein appeared to be distributed throughout the nucleus and cytoplasm, in contrast with the specific localization of the viral proteins.

Autographa californica Multiple Nucleopolyhedrovirus 38K Is a Novel Nucleocapsid Protein That Interacts with VP1054, VP39, VP80, and Itself

“…In contrast, the areas surrounding the nucleocapsids, such as the electron-condensed nucleic acid region of the stroma, the membrane profiles of the enveloping nucleocapsid bundles or of ODVs, or the protein matrix of polyhedra, showed no obvious 38K staining. Gold particles appeared to be distributed over the cylindrical capsid sheath of nucleocapsids, which is similar to the localization pattern of the major capsid shell protein VP39 (37). The localization pattern of 38K is different from that of PP78/83, which is associated with the ends of the capsids containing the basal structure (36); from that of PP31, which is associated with the electron-condensed matte (14); and from that of ODV-E66, which is associated with the intranuclear microvesicles and the envelope of ODV (17).…”

The gene encoding the capsid protein P82 of the Choristoneura fumiferana multicapsid nucleopolyhedrovirus: sequencing, transcription and characterization by immunoblot analysis.

“…Some proteins are common to both ODV and BV structures, including a capsid protein (P39) and another putative capsid protein (P87). The P39 is a component of the capsid, which has been confirmed by immunoelectron microscopy (Russell et al, 1991). The P87 was first identified as another capsid protein in Orgyia pseudotsugata MNPV (OpMNPV) (Mu$ ller et al, 1990).…”

Analysis of p74, a PDV envelope protein of Autographa californica nucleopolyhedrovirus required for occlusion body infectivity in vivo.

“…Both virion phenotypes share a common capsid structure 40-50 nm in diameter and 200-400 nm in length, comprising a nucleoprotein core (Tweeten et al, 1980 ;Wilson et al, 1987) encapsulated in a capsid shell (Rohrmann, 1992). Structural polypeptides of the nucleocapsid P. Faulkner and others P. Faulkner and others of Autographa californica nuclear polyhedrosis virus (AcMNPV) include a 39 kDa major capsid species (Thiem & Miller, 1989 ;Russell et al, 1991) and a highly basic 6n9 kDa polypeptide (Tweeten et al, 1980 ;Wilson et al, 1987 ;Maeda et al, 1991) complexed to the viral genome. In addition, a 24 kDa polypeptide was found to be evenly distributed through the nucleocapsid (Wolgamot et al, 1993) and a 78 kDa phosphoprotein essential for virus propagation was localized to the end of the capsid (Vialard & Richardson, 1993).…”