scholarly journals Influence of GlycoGag on the Incorporation of Host Membrane Proteins Into the Envelope of the Moloney Murine Leukemia Virus

2021 ◽  
Vol 1 ◽  
Author(s):  
Mariam Maltseva ◽  
Marc-André Langlois
Keyword(s):  
Murine Leukemia Virus ◽  
Viral Particle ◽  
Leukemia Virus ◽  
Viral Envelope ◽  
Host Protein ◽  
Viral Population ◽  
Phenotypic Characterization ◽  
Particle Level ◽  
Protein Incorporation ◽  
Murine Leukemia

Analysis of viral particle heterogeneity produced from infected cells has been limited by the inefficiency of traditional analytical methods to characterize large populations of viruses at an individual particle level. Flow virometry (FVM) is an emerging technique based on flow cytometry principles that enables a high throughput, multiparametric, and phenotypic characterization of viruses at a single particle resolution. Here, we performed FVM to analyze surface markers found on Murine Leukemia Virus (MLV) and glycosylated Gag-deficient (glycoGag) MLV. The glycoGag viral accessory protein has several roles in the MLV viral infection cycle including directing retroviral assembly and particle release at lipid rafts. Based on previous studies, we hypothesize that glycoGag modulates host protein incorporation into the viral envelope during viral assembly and budding. Here, by using FVM, we reveal that glycoGag is associated with an increased incorporation of the host-derived tetraspanins CD81 and CD63 along with the lipid raft marker and immune antigen Thy1.2 during the assembly and release of viral particles from infected NIH 3T3, EL4, and primary CD4+ T cells. Moreover, we show differences in the uptake of host proteins by viruses that are released from the two cell lines and primary T lymphocytes. Additionally, at the individual viral particle level, we observed a degree of expression heterogeneity of host-derived antigens within the viral population. Finally, certain cellular antigens can show either enrichment or exclusion from the viral envelope depending on whether glycoGag is expressed by the virus. This suggests that glycoGag is involved in a mechanism of selective host protein incorporation into the viral envelope.

scholarly journals Mutational Analysis of the N-Terminal Domain of Moloney Murine Leukemia Virus Capsid Protein

2007 ◽  
Vol 81 (22) ◽  
pp. 12337-12347 ◽  
Author(s):  
Marcy R. Auerbach ◽  
Kristy R. Brown ◽  
Ila R. Singh
Keyword(s):  
Murine Leukemia Virus ◽  
Mutational Analysis ◽  
Leukemia Virus ◽  
Host Protein ◽  
Moloney Murine Leukemia Virus ◽  
Structural Defects ◽  
Retroviral Infection ◽  
Functional Region ◽  
Terminal Domain ◽  
Murine Leukemia

ABSTRACT Retroviral capsid (CA) proteins contain a structurally conserved N-terminal domain (NTD) consisting of a β-hairpin and six to seven α-helices. To examine the role of this domain in Moloney murine leukemia virus (MoMLV) replication, we analyzed 18 insertional mutations in this region. All mutants were noninfectious. Based on the results of this analysis and our previous studies on additional mutations in this domain, we were able to divide the NTD of MoMLV CA into three functional regions. The first functional region included the region near the N terminus that forms the β-hairpin and was shown to control normal maturation of virions. The second region included the helix 4/5 loop and was essential for the formation of spherical cores. The third region encompassed most of the NTD except for the above loop. Mutants of this region assembled imperfect cores, as seen by detailed electron microscopy analyses, yet the resulting particles were efficiently released from cells. The mutants were defective at a stage immediately following entry of the core into cells. Despite possessing functional reverse transcriptase machinery, these mutant virions did not initiate reverse transcription in cells. This block could be due to structural defects in the assembling core or failure of an essential host protein to interact with the mutant CA protein, both of which may prevent correct disassembly upon entry of the virus into cells. Future studies are needed to understand the mechanism of these blocks and to target these regions pharmacologically to inhibit retroviral infection at additional stages.

scholarly journals THE VIRAL ENVELOPE GLYCOPROTEIN OF MURINE LEUKEMIA VIRUS AND THE PATHOGENESIS OF IMMUNE COMPLEX GLOMERULONEPHRITIS OF NEW ZEALAND MICE

1974 ◽  
Vol 140 (4) ◽  
pp. 1011-1027 ◽  
Author(s):  
Takashi Yoshiki ◽  
Robert C. Mellors ◽  
Mette Strand ◽  
J. T. August
Keyword(s):  
New Zealand ◽  
Immune Complex ◽  
Envelope Glycoprotein ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Viral Envelope ◽  
High Concentration ◽  
Immune Complex Glomerulonephritis ◽  
Viral Envelope Glycoprotein ◽  
Murine Leukemia

The use of monospecific antisera for the analysis by radioimmunoassay and immunofluorescence study of two major viral proteins, gp69/71 and p30 of murine leukemia virus, that could be of significance in the pathogenesis of immune complex glomerulonephritis of mice, particularly NZB and B/WF1 hybrid mice, yielded the following conclusions. A remarkably high concentration of viral envelope glycoprotein, gp69/71, was detected in the spleen and serum of New Zealand mice (NZB, NZW, B/WF1, and W/BF1); the concentration in the spleen was 10-fold greater than that found in AKR mice and 30-fold greater than that present in C57BL/6 mice. The gp69/71 was deposited along with bound immunoglobulins, apparently as an immune complex, in the diseased kidneys of mice, and the glomerular site and extent of deposition of gp69/71 was related to the severity of the glomerulonephritis. This study suggests that the pathogenesis of immune complex glomerulonephritis (and vasculitis) in mice is related to the expression of this specific viral envelope glycoprotein and to the host immune response to this protein.

scholarly journals Relationship of infectious murine leukemia virus and virus-related antigens in genetic crosses between AKR and the Fv-1 compatible strain C57L.

1976 ◽  
Vol 143 (1) ◽  
pp. 32-46 ◽  
Author(s):  
H Ikeda ◽  
W P Rowe ◽  
E A Boyse ◽  
E Stockert ◽  
H Sato ◽  
...  
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Specific Antigen ◽  
Viral Envelope ◽  
Progeny Testing ◽  
Chromosomal Genes ◽  
Relationship Of ◽  
Akr Mice ◽  
Murine Leukemia ◽  
High Output

In a further genetic study of murine leukemia virus (MuLV) and its components we examined the backcross C57L X (C57L X AKR). This population was selected because strains AKR and C57L are both Fv-1n, and the restriction which the Fu-1b allele imposes on the output of virus was thereby obviated. The segregants were scored for three characters: (a) infectious Gross-AKR-type MuLV (V), in the tail; (b) group-specific antigen indicative of p30 internal viral protein, in spleen; and (c) GIX antigen, now thought to be indicative of gp69/71 viral envelope glycoprotein, on thymocytes. Our conclusions are: (a) It is confirmed that the AKR mouse has two unlinked chromosomal genes, Akv-1 and Akv-2, each of which can independently give rise to the life-long high output of MuLV that is characteristic of AKR mice. (b) Of the eight phenotypes that could possibly be derived from segregation of the three pairs of independent alternative traits, seven were observed, but on progeny testing only three were shown to reflect stably heritable genotypes; these were V+p30+GIX+ and V-p30-GIX- (the parental types) and V-p30+GIX+. A third, newly identified AKR gene, designated Akvp, segregating independently of Akv-1 and Akv-2, also determines expression of p30 and GIX but in this case independently of XC-detectable MuLV. (c) The four remaining observed phenotypes, which did not breed true on progeny testing, involved mostly antigen-negative parents yielding antigen-positive progeny; it is likely that these discrepancies represented suppression of phenotype by a maternal resistance factor.

scholarly journals SERINC5 Potently Restricts Retrovirus Infection In Vivo

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Uddhav Timilsina ◽  
Supawadee Umthong ◽  
Brian Lynch ◽  
Aimee Stablewski ◽  
Spyridon Stavrou
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Viral Envelope ◽  
The Other ◽  
Immunodeficiency Virus ◽  
Retrovirus Infection ◽  
Hiv 1 ◽  
Murine Leukemia

ABSTRACT The serine incorporator (SERINC) proteins are multipass transmembrane proteins that affect sphingolipid and phosphatidylserine synthesis. Human SERINC5 and SERINC3 were recently shown to possess antiretroviral activity for a number of retroviruses, including human immunodeficiency virus (HIV), murine leukemia virus (MLV), and equine infectious anemia virus (EIAV). In the case of MLV, the glycosylated Gag (glyco-Gag) protein was shown to counteract SERINC5-mediated restriction in in vitro experiments and the viral envelope was found to determine virion sensitivity or resistance to SERINC5. However, nothing is known about the in vivo function of SERINC5. Antiretroviral function of a host factor in vitro is not always associated with antiretroviral function in vivo. Using SERINC5−/− mice that we had generated, we showed that mouse SERINC5 (mSERINC5) restriction of MLV infection in vivo is influenced not only by glyco-Gag but also by the retroviral envelope. Finally, we also examined the in vivo function of the other SERINC gene with known antiretroviral functions, SERINC3. By using SERINC3−/− mice, we found that the murine homologue, mSERINC3, had no antiretroviral role either in vivo or in vitro. To our knowledge, this report provides the first data showing that SERINC5 restricts retrovirus infection in vivo and that restriction of retrovirus infectivity in vivo is dependent on the presence of both glyco-Gag and the viral envelope. IMPORTANCE This study examined for the first time the in vivo function of the serine incorporator (SERINC) proteins during retrovirus infection. SERINC3 and SERINC5 (SERINC3/5) restrict a number of retroviruses, including human immunodeficiency virus 1 (HIV-1) and murine leukemia virus (MLV), by blocking their entry into cells. Nevertheless, HIV-1 and MLV encode factors, Nef and glycosylated Gag, respectively, that counteract SERINC3/5 in vitro. We recently developed SERINC3 and SERINC5 knockout mice to examine the in vivo function of these genes. We found that SERINC5 restriction is dependent on the absence of glycosylated Gag and the expression of a specific viral envelope glycoprotein. On the other hand, SERINC3 had no antiviral function. Our findings have implications for the development of therapeutics that target SERINC5 during retrovirus infection.

scholarly journals Murine leukemia virus transmembrane protein R-peptide is found in small virus core-like complexes in cells

2006 ◽  
Vol 87 (6) ◽  
pp. 1583-1588 ◽  
Author(s):  
Klaus Bahl Andersen ◽  
Huong Ai Diep ◽  
Anne Zedeler
Keyword(s):  
Cell Membrane ◽  
Murine Leukemia Virus ◽  
Transmembrane Protein ◽  
Leukemia Virus ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Virus Core ◽  
Small Virus ◽  
Murine Leukemia ◽  
In Cells

The core of the retrovirus Murine leukemia virus (MLV) consists of the Gag precursor protein and viral RNA. It assembles at the cytoplasmic face of the cell membrane where, by an unclear mechanism, it collects viral envelope proteins embedded in the cell membrane and buds off. The C-terminal half of the short cytoplasmic tail of the envelope transmembrane protein (TM) is cleaved off to yield R-peptide and fusion-active TM. In Moloney MLV particles, R-peptide was found to bind to core particles. In cells, R-peptide and low amounts of uncleaved TM were found to be associated with small core-like complexes, i.e. mild detergent-insoluble, Gag-containing complexes with a density of 1.23 g ml−1 and a size of 150–200 S. Our results suggest that TM associates with the assembling core particle through the R-peptide before budding and that this is the mechanism by which the budding virus acquires the envelope proteins.

scholarly journals Friend murine leukemia virus-induced leukemia is associated with the formation of mink cell focus-inducing viruses and is blocked in mice expressing endogenous mink cell focus-inducing xenotropic viral envelope genes.

1981 ◽  
Vol 154 (3) ◽  
pp. 907-920 ◽  
Author(s):  
S Ruscetti ◽  
L Davis ◽  
J Feild ◽  
A Oliff
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Viral Envelope ◽  
Envelope Gene ◽  
Related Protein ◽  
Newborn Mice ◽  
Endogenous Expression ◽  
Mink Cell ◽  
Resistant Strains ◽  
Murine Leukemia

In these studies, we have shown data that are consistent with the hypothesis that mink cell focus-inducing viruses (MCF) play an important role in the generation of an erythroproliferative disease developing after injection of certain strains of newborn mice with ecotropic Friend murine leukemia virus (F-MuLV). Resistance to this disease is correlated with the endogenous expression of an MCF/xenotropic virus-gp70-related protein that may interfere with the replication or spread of MCF viruses. These ideas are supported by the following observations: (a) after infection with F-MuLV, only 6/13 strains of mice-developed disease, and studies with crosses between susceptible and resistant strains indicated that resistance was dominant. Although F-MuLV was shown to replicate equally well in all strains tested, viruses coding for MCF-specific viral envelope proteins could be detected only in the spleens of mice from strains that were resistant to F-MuLV-induced disease and not in the spleens of mice from strains that were resistant to F-MuLV-induced disease; (b) a Friend MCF (Fr-MCF) virus isolated from the spleen of an F-MuLV-infected mouse from a susceptible strain induced the same erythroproliferative disease when injected as an appropriate pseudotype into mice from susceptible but not resistant strains of mice; and (c) resistant but not susceptible strains of mice endogenously express MCF/xenotropic virus-related envelope glycoproteins that may be responsible for resistance by blocking receptors for MCF viruses. These results not only indicate that Fr-MCF virus is a crucial intermediate in the induction of disease by F-MuLV, but also suggest that a novel gene, either an MCF/xenotropic virus-related envelope gene or a gene controlling its expression, is responsible for resistance to erythroleukemia induced by F-MuLV.

scholarly journals Induction of Endoplasmic Reticulum Stress in Thymic Lymphocytes by the Envelope Precursor Polyprotein of a Murine Leukemia Virus during the Preleukemic Period

2007 ◽  
Vol 81 (8) ◽  
pp. 4374-4377 ◽  
Author(s):  
Fayth K. Yoshimura ◽  
Xixia Luo
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Viral Envelope ◽  
Virus Envelope ◽  
Thymic Lymphocyte ◽  
Mink Cell ◽  
Induced Apoptosis ◽  
Murine Leukemia

ABSTRACT Infection of thymic lymphocytes by a mink cell focus-forming murine leukemia virus induces apoptosis during the preleukemic period of lymphomagenesis. In this study, we observed that during this period, the viral envelope precursor polyprotein accumulated to high levels in thymic lymphocytes from mice inoculated with virus. Envelope accumulation occurred with the same kinetics as the induction of endoplasmic reticulum (ER) stress, which resulted in the upregulation of the 78-kDa glucose-regulated protein (GRP78). In thymic lymphomas, GRP78 levels were higher than those in virus-infected preleukemic cells, and GRP58 was upregulated. These results suggest that Env precursor accumulation induces ER stress, which participates in thymic lymphocyte apoptosis. The subsequent upregulation of ER chaperone proteins GRP78 and GRP58 may contribute to rescuing cells from virus-induced apoptosis.

scholarly journals Rapid and Sensitive Detection of Retrovirus Entry by Using a Novel Luciferase-Based Content-Mixing Assay

2004 ◽  
Vol 78 (10) ◽  
pp. 5124-5132 ◽  
Author(s):  
Andrey A. Kolokoltsov ◽  
Robert A. Davey
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Detailed Examination ◽  
Viral Envelope ◽  
Live Cells ◽  
Viral Envelope Protein ◽  
Cellular Targets ◽  
Mode Of Entry ◽  
Endosomal Acidification ◽  
Murine Leukemia

ABSTRACT We describe a novel assay that permits measurement of entry of murine leukemia virus and pseudotypes with greater sensitivity and more rapidly than previously possible. To achieve this, we encapsulated a sensitive reporter enzyme, luciferase, directly into fully infectious, intact viral particles. The enzyme is specifically targeted to the viral lumen, as a C-terminal fusion on the viral envelope protein. Only when the incorporated luciferase is released from the viral lumen and gains access to its substrates is light emitted and readily detected. When cells are perfused with luciferin, quantitative measurements of entry can be made in real time on live cells. Uniquely, the amount of cell-bound virus can be determined in the same assay by addition of detergent to expose the luciferase. We demonstrate that virus carrying a mutation in the fusion peptide binds normally to cells but is unable to infect them and gives no entry signal. Using this assay, we show that inhibitors of endosomal acidification inhibit signal from vesicular stomatitis virus pseudotypes but not murine leukemia virus, consistent with a pH-independent mode of entry for the latter virus. Additionally, the fusion kinetics are rapid, with a half-life of 25 min after a delay of 10 to 15 min. The future use of this assay will permit a detailed examination of the entry mechanism of viruses and provide a convenient platform to discover novel entry inhibitors. The design also permits packaging of potential therapeutic protein cargoes into functional virus particles and their specific delivery to cellular targets.

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