scholarly journals Identification of a Conserved Residue of Foamy Virus Gag Required for Intracellular Capsid Assembly

2001 ◽  
Vol 75 (15) ◽  
pp. 6857-6864 ◽  
Author(s):  
Scott W. Eastman ◽  
Maxine L. Linial
Keyword(s):  
Foamy Virus ◽  
Specific Interaction ◽  
Capsid Assembly ◽  
Particle Assembly ◽  
Simian Foamy Virus ◽  
Viral Budding ◽  
Extracellular Release ◽  
Infected Cells ◽  
Targeting Signal ◽  
Strict Requirement

ABSTRACT In contrast to all retroviruses but similar to the hepatitis B virus, foamy viruses (FV) require expression of the envelope protein for budding of intracellular capsids from the cell, suggesting a specific interaction between the Gag and Env proteins. Capsid assembly occurs in the cytoplasm of infected cells in a manner similar to that for the B- and D-type viruses; however, in contrast to these retroviruses, FV Gag lacks an N-terminal myristylation signal and capsids are not targeted to the plasma membrane (PM). We have found that mutation of an absolutely conserved arginine (Arg) residue at position 50 to alanine (R50A) of the simian foamy virus SFV cpz(hu) inhibits proper capsid assembly and abolishes viral budding even in the presence of the envelope (Env) glycoproteins. Particle assembly and extracellular release of virus can be restored to this mutant with the addition of an N-terminal Src myristylation signal (Myr-R50A), presumably by providing an alternate site for assembly to occur at the PM. In addition, the strict requirement of Env expression for capsid budding can be bypassed by addition of a PM-targeting signal to Gag. These results suggest that intracellular capsid assembly may be mediated by a signal akin to the cytoplasmic targeting and retention signal CTRS found in Mason-Pfizer monkey virus and that FV Gag has the inherent ability to assemble capsids at multiple sites like conventional retroviruses. The necessity of Env expression for particle egress is most probably due to the lack of a membrane-targeting signal within FV Gag to direct capsids to the PM for release and indicates that Gag-Env interactions are essential to drive particle budding.

Structural analysis of proviral DNA in simian foamy virus (LK-3)-infected cells

1989 ◽  
Vol 109 (1-2) ◽  
pp. 103-114 ◽  
Author(s):  
M. Schweizer ◽  
R. Renne ◽  
D. Neumann-Haefelin
Keyword(s):  
Structural Analysis ◽  
Foamy Virus ◽  
Simian Foamy Virus ◽  
Proviral Dna ◽  
Infected Cells

scholarly journals N-Terminal Gag Domain Required for Foamy Virus Particle Assembly and Export

2005 ◽  
Vol 79 (19) ◽  
pp. 12464-12476 ◽  
Author(s):  
Marc Cartellieri ◽  
Ottmar Herchenröder ◽  
Wolfram Rudolph ◽  
Martin Heinkelein ◽  
Dirk Lindemann ◽  
...  
Keyword(s):  
Envelope Protein ◽  
Signal Sequence ◽  
Foamy Virus ◽  
Point Mutations ◽  
Particle Morphology ◽  
Particulate Material ◽  
Capsid Assembly ◽  
Particle Assembly ◽  
Gag Proteins ◽  
Protein Incorporation

ABSTRACT Among the Retroviridae, foamy viruses (FVs) exhibit an unusual way of particle assembly and a highly specific incorporation of envelope protein into progeny virions. We have analyzed deletions and point mutants of the prototypic FV gag gene for capsid assembly and egress, envelope protein incorporation, infectivity, and ultrastructure. Deletions introduced at the 3′ end of gag revealed the first 297 amino acids (aa) to be sufficient for specific Env incorporation and export of particulate material. Deletions introduced at the 5′ end showed the region between aa 6 and 200 to be dispensable for virus capsid assembly but required for the incorporation of Env and particle egress. Point mutations were introduced in the 5′ region of gag to target residues conserved among FVs from different species. Alanine substitutions of residues in a region between aa 40 and 60 resulted in severe alterations in particle morphology. Furthermore, at position 50, this region harbors the conserved arginine that is presumably at the center of a signal sequence directing FV Gag proteins to a cytoplasmic assembly site.

scholarly journals Contemporary Distribution, Estimated Age, and Prehistoric Migrations of Old World Monkey Retroviruses

Epidemiologia ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 46-67
Author(s):  
Antoinette C. van der Kuyl
Keyword(s):  
Close Contact ◽  
World Monkey ◽  
Foamy Virus ◽  
Endogenous Retrovirus ◽  
Papio Cynocephalus ◽  
Endogenous Virus ◽  
Simian Foamy Virus ◽  
Old World ◽  
T Lymphotropic Virus ◽  
Type D

Old World monkeys (OWM), simians inhabiting Africa and Asia, are currently affected by at least four infectious retroviruses, namely, simian foamy virus (SFV), simian immunodeficiency virus (SIV), simian T-lymphotropic virus (STLV), and simian type D retrovirus (SRV). OWM also show chromosomal evidence of having been infected in the past with four more retroviral species, baboon endogenous virus (BaEV), Papio cynocephalus endogenous virus (PcEV), simian endogenous retrovirus (SERV), and Rhesus endogenous retrovirus-K (RhERV-K/SERV-K1). For some of the viruses, transmission to other primates still occurs, resulting, for instance, in the HIV pandemic. Retroviruses are intimately connected with their host as they are normally spread by close contact. In this review, an attempt to reconstruct the distribution and history of OWM retroviruses will be made. A literature overview of the species infected by any of the eight retroviruses as well as an age estimation of the pathogens will be given. In addition, primate genomes from databases have been re-analyzed for the presence of endogenous retrovirus integrations. Results suggest that some of the oldest retroviruses, SERV and PcEV, have travelled with their hosts to Asia during the Miocene, when a higher global temperature allowed simian expansions. In contrast, younger viruses, such as SIV and SRV, probably due to the lack of a primate continuum between the continents in later times, have been restricted to Africa and Asia, respectively.

scholarly journals Simian Foamy Virus Transmission from Apes to Humans, Rural Cameroon

2007 ◽  
Vol 13 (9) ◽  
pp. 1314-1320 ◽  
Author(s):  
Sara Calattini ◽  
Edouard B.A. Betsem ◽  
Alain Froment ◽  
Philippe Mauclère ◽  
Patricia Tortevoye ◽  
...  
Keyword(s):  
Foamy Virus ◽  
Virus Transmission ◽  
Simian Foamy Virus ◽  
Rural Cameroon

scholarly journals Novel Simian Foamy Virus infection of wild Indian rhesus macaque (Macaca mulatta)

Retrovirology ◽  
2011 ◽  
Vol 8 (S1) ◽  
Author(s):  
Jayashree S Nandi ◽  
Anil K Chhangani ◽  
Surendra M Mohnot
Keyword(s):  
Virus Infection ◽  
Rhesus Macaque ◽  
Macaca Mulatta ◽  
Foamy Virus ◽  
Simian Foamy Virus ◽  
Indian Rhesus Macaque

scholarly journals Function, Architecture, and Biogenesis of Reovirus Replication Neoorganelles

Viruses ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 288 ◽  
Author(s):  
Raquel Tenorio ◽  
Isabel Fernández de Castro ◽  
Jonathan J. Knowlton ◽  
Paula F. Zamora ◽  
Danica M. Sutherland ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Host Cells ◽  
Genome Replication ◽  
Nonstructural Proteins ◽  
Particle Assembly ◽  
The Matrix ◽  
Viral Genome Replication ◽  
Pathogenic Viruses ◽  
Infected Cells ◽  
Reovirus Replication

Most viruses that replicate in the cytoplasm of host cells form neoorganelles that serve as sites of viral genome replication and particle assembly. These highly specialized structures concentrate viral proteins and nucleic acids, prevent the activation of cell-intrinsic defenses, and coordinate the release of progeny particles. Reoviruses are common pathogens of mammals that have been linked to celiac disease and show promise for oncolytic applications. These viruses form nonenveloped, double-shelled virions that contain ten segments of double-stranded RNA. Replication organelles in reovirus-infected cells are nucleated by viral nonstructural proteins µNS and σNS. Both proteins partition the endoplasmic reticulum to form the matrix of these structures. The resultant membranous webs likely serve to anchor viral RNA–protein complexes for the replication of the reovirus genome and the assembly of progeny virions. Ongoing studies of reovirus replication organelles will advance our knowledge about the strategies used by viruses to commandeer host biosynthetic pathways and may expose new targets for therapeutic intervention against diverse families of pathogenic viruses.

scholarly journals Particle Assembly and Ultrastructural Features Associated with Replication of the Lytic Archaeal Virus Sulfolobus Turreted Icosahedral Virus

2009 ◽  
Vol 83 (12) ◽  
pp. 5964-5970 ◽  
Author(s):  
Susan K. Brumfield ◽  
Alice C. Ortmann ◽  
Vincent Ruigrok ◽  
Peter Suci ◽  
Trevor Douglas ◽  
...  
Keyword(s):  
Time Course ◽  
Plaque Assay ◽  
Ultrastructural Changes ◽  
Progeny Virus ◽  
Particle Assembly ◽  
Virus Particles ◽  
Transmission Electron ◽  
Archaeal Viruses ◽  
Infected Cells ◽  
Sulfolobus Turreted Icosahedral Virus

ABSTRACT Little is known about the replication cycle of archaeal viruses. We have investigated the ultrastructural changes of Sulfolobus solfataricus P2 associated with infection by Sulfolobus turreted icosahedral virus (STIV). A time course of a near synchronous STIV infection was analyzed using both scanning and transmission electron microscopy. Assembly of STIV particles, including particles lacking DNA, was observed within cells, and fully assembled STIV particles were visible by 30 h postinfection (hpi). STIV was determined to be a lytic virus, causing cell disruption beginning at 30 hpi. Prior to cell lysis, virus infection resulted in the formation of pyramid-like projections from the cell surface. These projections, which have not been documented in any other host-virus system, appeared to be caused by the protrusion of the cell membrane beyond the bordering S-layer. These structures are thought to be sites at which progeny virus particles are released from infected cells. Based on these observations of lysis, a plaque assay was developed for STIV. From these studies we propose an overall assembly model for STIV.

scholarly journals Human Foamy Virus Capsid Formation Requires an Interaction Domain in the N Terminus of Gag

2001 ◽  
Vol 75 (9) ◽  
pp. 4367-4375 ◽  
Author(s):  
Joelle Tobaly-Tapiero ◽  
Patricia Bittoun ◽  
Marie-Lou Giron ◽  
Manuel Neves ◽  
Marcel Koken ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Foamy Virus ◽  
Coiled Coil ◽  
Capsid Assembly ◽  
Human Foamy Virus ◽  
Viral Production ◽  
Reporter Protein ◽  
Interaction Domain ◽  
Capsid Formation ◽  
N Terminus

ABSTRACT Retroviral Gag expression is sufficient for capsid assembly, which occurs through interaction between distinct Gag domains. Human foamy virus (HFV) capsids assemble within the cytoplasm, although their budding, which mainly occurs in the endoplasmic reticulum, requires the presence of homologous Env. Yet little is known about the molecular basis of HFV Gag precursor assembly. Using fusions between HFV Gag and a nuclear reporter protein, we have identified a strong interaction domain in the N terminus of HFV Gag which is predicted to contain a conserved coiled-coil motif. Deletion within this region in an HFV provirus abolishes viral production through inhibition of capsid assembly.

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