Efficient pseudotyping of murine leukemia virus particles with chimeric human foamy virus envelope proteins.

ABSTRACT The function of the N terminus of the murine leukemia virus (MuLV) surface (SU) protein was examined. A series of five chimeric envelope proteins (Env) were generated in which the N terminus of amphotropic 4070A was replaced by equivalent sequences from ecotropic Moloney MuLV (M-MuLV). Viral titers of these chimeras indicate that exchange with homologous sequences could be tolerated, up to V17eco/T15ampho (crossover III). Constructs encoding the first 28 amino acids (aa) of ecotropic M-MuLV resulted in Env expression and binding to the receptor; however, the virus titer was reduced 5- to 45-fold, indicating a postbinding block. Additional exchange beyond the first 28 aa of ecotropic MuLV Env resulted in defective protein expression. These N-terminal chimeras were also introduced into the AE4 chimeric Env backbone containing the amphotropic receptor binding domain joined at the hinge region to the ecotropic SU C terminus. In this backbone, introduction of the first 17 aa of the ecotropic Env protein significantly increased the titer compared to that of its parental chimera AE4, implying a functional coordination between the N terminus of SU and the C terminus of the SU and/or transmembrane proteins. These data functionally dissect the N-terminal sequence of the MuLV Env protein and identify differential effects on receptor-mediated entry.

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Analysis of the cell fusion activities of chimeric simian immunodeficiency virus-murine leukemia virus envelope proteins: inhibitory effects of the R peptide.

Journal of Virology ◽

10.1128/jvi.70.1.248-254.1996 ◽

1996 ◽

Vol 70 (1) ◽

pp. 248-254 ◽

Cited By ~ 49

Author(s):

C Yang ◽

R W Compans

Keyword(s):

Simian Immunodeficiency Virus ◽

Cell Fusion ◽

Murine Leukemia Virus ◽

Leukemia Virus ◽

Envelope Proteins ◽

Inhibitory Effects ◽

Virus Envelope ◽

Immunodeficiency Virus ◽

Murine Leukemia

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The Role of the Membrane-spanning Domain Sequence in Glycoprotein-mediated Membrane Fusion

Molecular Biology of the Cell ◽

10.1091/mbc.10.9.2803 ◽

1999 ◽

Vol 10 (9) ◽

pp. 2803-2815 ◽

Cited By ~ 44

Author(s):

Gwen M. Taylor ◽

David Avram Sanders

Keyword(s):

Membrane Fusion ◽

Murine Leukemia Virus ◽

Leukemia Virus ◽

Envelope Proteins ◽

Viral Fusion ◽

Virus Envelope ◽

Membrane Spanning ◽

Membrane Spanning Domains ◽

Murine Leukemia

The role of glycoprotein membrane-spanning domains in the process of membrane fusion is poorly understood. It has been demonstrated that replacing all or part of the membrane-spanning domain of a viral fusion protein with sequences that encode signals for glycosylphosphatidylinositol linkage attachment abrogates membrane fusion activity. It has been suggested, however, that the actual amino acid sequence of the membrane-spanning domain is not critical for the activity of viral fusion proteins. We have examined the function of Moloney murine leukemia virus envelope proteins with substitutions in the membrane-spanning domain. Envelope proteins bearing substitutions for proline 617 are processed and incorporated into virus particles normally and bind to the viral receptor. However, they possess greatly reduced or undetectable capacities for the promotion of membrane fusion and infectious virus particle formation. Our results imply a direct role for the residues in the membrane-spanning domain of the murine leukemia virus envelope protein in membrane fusion and its regulation. They also support the thesis that membrane-spanning domains possess a sequence-dependent function in other protein-mediated membrane fusion events.

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Recent Studies on a Murine Leukemia Virus Grown in Tissue Culture

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060544 ◽

1967 ◽

Vol 25 ◽

pp. 106-107

Author(s):

L. Z. de Tkaczevski ◽

E. de Harven ◽

C. Friend

Keyword(s):

Tissue Culture ◽

Solid Tumors ◽

Murine Leukemia Virus ◽

Leukemia Virus ◽

Supernatant Fluid ◽

Virus Particles ◽

Friend Leukemia ◽

Type C ◽

Leukemia Viruses ◽

Murine Leukemia

Despite extensive studies, the correlation between the morphology and pathogenicity of murine leukemia viruses (MLV) has not yet been clarified. The virus particles found in the plasma of leukemic mice belong to 2 distinct groups, 1 or 2% of them being enveloped A particles and the vast majority being of type C. It is generally believed that these 2 types of particles represent different phases in the development of the same virus. Particles of type A have been thought to be an earlier form of type C particles. One of the tissue culture lines established from Friend leukemia solid tumors has provided the material for the present study. The supernatant fluid of the line designated C-1A contains an almost pure population of A particles as illustrated in Figure 1. The ratio is, therefore, the reverse of what is unvariably observed in the plasma of leukemic mice where C particles predominate.

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