Structure and assembly of intracellular mature vaccinia virus: Isolated-particle analysis

Citation
G. Griffiths et al., Structure and assembly of intracellular mature vaccinia virus: Isolated-particle analysis, J VIROLOGY, 75(22), 2001, pp. 11034-11055
Citations number
51
Categorie Soggetti
Microbiology
Journal title
JOURNAL OF VIROLOGY
ISSN journal
0022538X → ACNP
Volume
75
Issue
22
Year of publication
2001
Pages
11034 - 11055
Database
ISI
SICI code
0022-538X(200111)75:22<11034:SAAOIM>2.0.ZU;2-O
Abstract
In a series of papers, we have provided evidence that during its assembly v accinia virus is enveloped by a membrane cisterna that originates from a sp ecialized, virally modified, smooth-membraned domain of the endoplasmic ret iculum (ER). Recently, however, Hollinshead et al. (M. Hollinshead, A. Vand erplasschen, G. I. Smith, and D. J. Vaux, J. Virol. 73:1503-1517, 1999) arg ued against this hypothesis, based on their interpretations of thin-section ed material. The present article is the first in a series of papers that de scribe a comprehensive electron microscopy (EM) analysis of the vaccinia In tracellular Mature Virus (JAM and the process of its assembly in HeLa cells . In this first study, we analyzed the IMV by on-grid staining, cryoscannin g EM (SEM), and cryo-transmission EM. We focused on the structure of the IM V particle, both after isolation and in the context of viral entry. For the latter, we used high-resolution cryo-SEM combined with cryofixation, as we ll as a novel approach we developed for investigating vaccinia IMV bound to plasma membrane fragments adsorbed onto EM grids. Our analysis revealed th at the IMV is made up of interconnected cisternal and tubular domains that fold upon themselves via a complex topology that includes an S-shaped fold. The vital tubules appear to be eviscerated from the particle during viral infection. Since the structure of the MINI is the result of a complex assem bly process, we also provide a working model to explain how a specialized s mooth-ER domain can be modulated to form the IMV. We also present theoretic al arguments for why it is highly unlikely that the IMV is surrounded by on ly a single membrane.