Surface expression of murine leukemia virus structural polypeptides on host cell and the virion

1978 ◽  
Vol 22 (2) ◽  
pp. 204-213 ◽  
Author(s):  
Josef Schneider ◽  
Gerhard Hunsmann
Keyword(s):  
Host Cell ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Surface Expression ◽  
Murine Leukemia

scholarly journals Suppression of a Fusion Defect by Second Site Mutations in the Ecotropic Murine Leukemia Virus Surface Protein

1999 ◽  
Vol 73 (6) ◽  
pp. 5034-5042 ◽  
Author(s):  
Tatiana Zavorotinskaya ◽  
Lorraine M. Albritton
Keyword(s):  
Host Cell ◽  
Cell Fusion ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Surface Protein ◽  
Host Cells ◽  
Virus Surface ◽  
Fusion Defect ◽  
Murine Leukemia ◽  
Cell Cell

ABSTRACT Entry of ecotropic murine leukemia virus initiates when the envelope surface protein recognizes and binds to the virus receptor on host cells. The envelope transmembrane protein then mediates fusion of viral and host cell membranes and penetration into the cytoplasm. Using a genetic selection, we isolated an infectious retrovirus variant containing three changes in the surface protein—histidine 8 to arginine, glutamine 227 to arginine, and aspartate 243 to tyrosine. Single replacement of histidine 8 with arginine (H8R) resulted in almost complete loss of infectivity, even though the mutant envelope proteins were stable and efficiently incorporated into virions. Virions carrying H8R envelope were proficient at binding cells expressing receptor but failed to induce cell-cell fusion of XC cells, indicating that the histidine at position 8 plays an essential role in fusion during penetration of the host cell membrane. Thus, there is at least one domain in SU that is involved in fusion; the fusion functions do not reside exclusively in TM. In contrast, envelope with all three changes induced cell-cell fusion of XC cells and produced virions that were 10,000-fold more infectious than those containing only the H8R substitution, indicating that changes at positions 227 and 243 can suppress a fusion defect caused by loss of histidine 8 function. Moreover, the other two changes acted synergistically, indicating that both compensate for the loss of the same essential function of histidine 8. The ability of these changes to suppress this fusion defect might provide a means for overcoming postbinding defects found in targeted retroviral vectors for use in human gene therapy.

scholarly journals The Human TRIM5α Restriction Factor Mediates Accelerated Uncoating of the N-Tropic Murine Leukemia Virus Capsid

2006 ◽  
Vol 81 (5) ◽  
pp. 2138-2148 ◽  
Author(s):  
Michel J. Perron ◽  
Matthew Stremlau ◽  
Mark Lee ◽  
Hassan Javanbakht ◽  
Byeongwoon Song ◽  
...  
Keyword(s):  
Host Cell ◽  
Reverse Transcription ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Restriction Factor ◽  
Viral Capsid ◽  
Wild Type ◽  
Host Cell Factors ◽  
Infected Cells ◽  
Murine Leukemia

ABSTRACT The host cell factors TRIM5αhu and Fv-1 restrict N-tropic murine leukemia virus (N-MLV) infection at an early postentry step before or after reverse transcription, respectively. Interestingly, the identity of residue 110 of the MLV capsid determines susceptibility to both TRIM5αhu and Fv-1. In this study, we investigate the fate of the MLV capsid in cells expressing either the TRIM5αhu or Fv-1 restriction factor. The expression of TRIM5αhu, but not Fv-1, specifically promoted the premature conversion of particulate N-MLV capsids within infected cells to soluble capsid proteins. The TRIM5αhu-mediated disassembly of particulate N-MLV capsids was dependent upon residue 110 of the viral capsid. Furthermore, the deletion or disruption of TRIM5αhu domains necessary for potent N-MLV restriction completely abrogated the disappearance of particulate N-MLV capsids observed with wild-type TRIM5αhu. These results suggest that premature disassembly of the viral capsid contributes to the restriction of N-MLV infection by TRIM5αhu, but not by Fv-1.

scholarly journals Host RNA Packaging by Retroviruses: A Newly Synthesized Story

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Matthew J. Eckwahl ◽  
Alice Telesnitsky ◽  
Sandra L. Wolin
Keyword(s):  
Life Cycle ◽  
Host Cell ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Noncoding Rnas ◽  
Small Nuclear Rna ◽  
Rna Packaging ◽  
Protein Partners ◽  
Nuclear Rna ◽  
Murine Leukemia

ABSTRACT A fascinating aspect of retroviruses is their tendency to nonrandomly incorporate host cell RNAs into virions. In addition to the specific tRNAs that prime reverse transcription, all examined retroviruses selectively package multiple host cell noncoding RNAs (ncRNAs). Many of these ncRNAs appear to be encapsidated shortly after synthesis, before assembling with their normal protein partners. Remarkably, although some packaged ncRNAs, such as pre-tRNAs and the spliceosomal U6 small nuclear RNA (snRNA), were believed to reside exclusively within mammalian nuclei, it was demonstrated recently that the model retrovirus murine leukemia virus (MLV) packages these ncRNAs from a novel pathway in which unneeded nascent ncRNAs are exported to the cytoplasm for degradation. The finding that retroviruses package forms of ncRNAs that are rare in cells suggests several hypotheses for how these RNAs could assist retrovirus assembly and infectivity. Moreover, recent experiments in several laboratories have identified additional ways in which cellular ncRNAs may contribute to the retrovirus life cycle. This review focuses on the ncRNAs that are packaged by retroviruses and the ways in which both encapsidated ncRNAs and other cellular ncRNAs may contribute to retrovirus replication.

Recent Studies on a Murine Leukemia Virus Grown in Tissue Culture

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.

Immunoferritin Labelling of Murine Leukemia Virus Antigens in thin Sections

1980 ◽  
Vol 38 ◽  
pp. 508-509
Author(s):  
Ray A. Weigand ◽  
Gregory C. Varjabedian
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Intracellular Localization ◽  
Uranyl Acetate ◽  
Antibody Technique ◽  
Thin Sections ◽  
Tumor Virus ◽  
Labelling Procedure ◽  
Unlabelled Antibody ◽  
Murine Leukemia

We previously described the intracellular localization of murine mammary tumor virus (MuMTV) p28 protein in thin sections (1). In that study, MuMTV containing cells fixed in 3% paraformaldehyde plus 0.05% glutaraldehyde were labelled after thin sectioning using ferritin-antiferritin in an unlabelled antibody technique. We now describe the labelling of murine leukemia virus (MuLV) particles using the unlabelled antibody technique coupled to ferritin-Fab antiferritin. Cultures of R-MuLV in NIH/3T3 cells were grown to 90% confluence (2), fixed with 2% paraformaldehyde plus 0.5% glutaraldehyde in 0.1 M cacodylate at pH 7.2, postfixed with buffered 17 OsO4, dehydrated with a series of etha-nols, and embedded in Epon. Thin sections were collected on nickel grids, incubated in 107 H2O2, rinsed in HEPES buffered saline, and subjected to the immunoferritin labelling procedure. The procedure included preincubation in 27 egg albumin, a four hour incubation in goat antisera against purified gp69/71 of MuLV (3) (primary antibody), incubation in F(ab’)2 fragments of rabbit antisera to goat IgG (secondary antibody), incubation in apoferritin, incubation in ferritin-Fab ferritin, and a brief fixation with 2% glutaraldehyde. The sections were stained with uranyl acetate and examined in a Siemens IA electron microscope at an accelerating voltage of 60 KV.

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