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Roles of Cellular NSF Protein in Entry and Nuclear Egress of Budded Virions of Autographa californica Multiple Nucleopolyhedrovirus
- Source :
- Journal of virology. 91(20)
- Publication Year :
- 2017
-
Abstract
- In eukaryotic cells, the s oluble N -ethylmaleimide- s ensitive f actor (NSF) a ttachment protein re ceptor (SNARE) proteins comprise the minimal machinery that triggers fusion of transport vesicles with their target membranes. Comparative studies revealed that genes encoding the components of the SNARE system are highly conserved in yeast, insect, and human genomes. Upon infection of insect cells by the virus Autographa californica multiple nucleopolyhedrovirus (AcMNPV), the transcript levels of most SNARE genes initially were upregulated. We found that overexpression of dominant-negative (DN) forms of NSF or knockdown of the expression of NSF, the key regulator of the SNARE system, significantly affected infectious AcMNPV production. In cells expressing DN NSF, entering virions were trapped in the cytoplasm or transported to the nucleus with low efficiency. The presence of DN NSF also moderately reduced trafficking of the viral envelope glycoprotein GP64 to the plasma membrane but dramatically inhibited production of infectious budded virions (BV). Transmission electron microscopy analysis of infections in cells expressing DN NSF revealed that progeny nucleocapsids were retained in a perinuclear space surrounded by inner and outer nuclear membranes. Several baculovirus conserved (core) proteins (Ac76, Ac78, GP41, Ac93, and Ac103) that are important for infectious budded virion production were found to associate with NSF, and NSF was detected within the assembled BV. Together, these data indicate that the cellular SNARE system is involved in AcMNPV infection and that NSF is required for efficient entry and nuclear egress of budded virions of AcMNPV. IMPORTANCE Little is known regarding the complex interplay between cellular factors and baculoviruses during viral entry and egress. Here, we examined the cellular SNARE system, which mediates the fusion of vesicles in healthy cells, and its relation to baculovirus infection. Using a DN approach and RNA interference knockdown, we demonstrated that a general disruption of the SNARE machinery significantly inhibited the production of infectious BV of AcMNPV. The presence of a DN NSF protein resulted in low-efficiency entry of BV and the retention of progeny nucleocapsids in the perinuclear space during egress. Combined with these effects, we also found that several conserved (core) baculovirus proteins closely associate with NSF, and these results suggest their involvement in the egress of BV. Our findings are the first to demonstrate that the SNARE system is required for efficient entry of BV and nuclear egress of progeny nucleocapsids of baculoviruses.
- Subjects :
- 0301 basic medicine
Cytoplasm
viruses
Immunology
Active Transport, Cell Nucleus
Biology
Spodoptera
Gp41
Microbiology
Cell Line
03 medical and health sciences
Viral envelope
Microscopy, Electron, Transmission
Viral Envelope Proteins
Viral entry
RNA interference
Virology
Yeasts
Sf9 Cells
Animals
Humans
Nucleocapsid
N-Ethylmaleimide-Sensitive Proteins
Virus Release
chemistry.chemical_classification
Cell Nucleus
Gene knockdown
Virus Assembly
fungi
Virion
Virus Internalization
biology.organism_classification
Nucleopolyhedroviruses
Cell biology
Virus-Cell Interactions
Autographa californica
030104 developmental biology
chemistry
Insect Science
RNA Interference
Glycoprotein
SNARE Proteins
Subjects
Details
- ISSN :
- 10985514
- Volume :
- 91
- Issue :
- 20
- Database :
- OpenAIRE
- Journal :
- Journal of virology
- Accession number :
- edsair.doi.dedup.....c9a516280e3cb3c192fd4618db67012b