scholarly journals Mutations in Both the Surface and Transmembrane Envelope Glycoproteins of the RAV-2 Subgroup B Avian Sarcoma and Leukosis Virus Are Required to Escape the Antiviral Effect of a Secreted Form of the TvbS3 Receptor †

Viruses ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 500 ◽  
Author(s):  
Xueqian Yin ◽  
Deborah C. Melder ◽  
William S. Payne ◽  
Jerry B. Dodgson ◽  
Mark J. Federspiel
Keyword(s):  
Virus Entry ◽  
Genetic Selection ◽  
Antiviral Effect ◽  
Viral Envelope ◽  
Host Protein ◽  
Surface Glycoprotein ◽  
Selection Strategies ◽  
Hypervariable Regions ◽  
Multiple Regions ◽  
Avian Sarcoma

The subgroup A through E avian sarcoma and leukosis viruses ASLV(A) through ASLV(E) are a group of highly related alpharetroviruses that have evolved to use very different host protein families as receptors. We have exploited genetic selection strategies to force the replication-competent ASLVs to naturally evolve and acquire mutations to escape the pressure on virus entry and yield a functional replicating virus. In this study, evolutionary pressure was exerted on ASLV(B) virus entry and replication using a secreted for of its Tvb receptor. As expected, mutations in the ASLV(B) surface glycoprotein hypervariable regions were selected that knocked out the ability for the mutant glycoprotein to bind the sTvbS3-IgG inhibitor. However, the subgroup B Rous associated virus 2 (RAV-2) also required additional mutations in the C-terminal end of the SU glycoprotein and multiple regions of TM highlighting the importance of the entire viral envelope glycoprotein trimer structure to mediate the entry process efficiently. These mutations altered the normal two-step ASLV membrane fusion process to enable infection.

scholarly journals Avian Sarcoma and Leukosis Virus Envelope Glycoproteins Evolve to Broaden Receptor Usage Under Pressure from Entry Competitors †

Viruses ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 519 ◽  
Author(s):  
Audelia Munguia ◽  
Mark J. Federspiel
Keyword(s):  
Binding Affinity ◽  
Genetic Selection ◽  
Hypervariable Region ◽  
Surface Proteins ◽  
Soluble Form ◽  
Envelope Glycoproteins ◽  
Virus Envelope ◽  
Receptor Usage ◽  
Hypervariable Regions ◽  
Avian Sarcoma

The subgroup A through E avian sarcoma and leukosis viruses (ASLV(A) through ASLV(E)) are a group of highly related alpharetroviruses that have evolved their envelope glycoproteins to use different receptors to enable efficient virus entry due to host resistance and/or to expand host range. Previously, we demonstrated that ASLV(A) in the presence of a competitor to the subgroup A Tva receptor, SUA-rIgG immunoadhesin, evolved to use other receptor options. The selected mutant virus, RCASBP(A)Δ155–160, modestly expanded its use of the Tvb and Tvc receptors and possibly other cell surface proteins while maintaining the binding affinity to Tva. In this study, we further evolved the Δ155–160 virus with the genetic selection pressure of a soluble form of the Tva receptor that should force the loss of Tva binding affinity in the presence of the Δ155–160 mutation. Viable ASLVs were selected that acquired additional mutations in the Δ155–160 Env hypervariable regions that significantly broadened receptor usage to include Tvb and Tvc as well as retaining the use of Tva as a receptor determined by receptor interference assays. A similar deletion in the hr1 hypervariable region of the subgroup C ASLV glycoproteins evolved to broaden receptor usage when selected on Tvc-negative cells.

scholarly journals An Unrelated Monoclonal Antibody Neutralizes Human Immunodeficiency Virus Type 1 by Binding to an Artificial Epitope Engineered in a Functionally Neutral Region of the Viral Envelope Glycoproteins

2005 ◽  
Vol 79 (9) ◽  
pp. 5616-5624 ◽  
Author(s):  
Xinping Ren ◽  
Joseph Sodroski ◽  
Xinzhen Yang
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Envelope Glycoprotein ◽  
Virus Entry ◽  
Neutralizing Antibody ◽  
Viral Envelope ◽  
Epitope Tag ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Neutralizing antibodies often recognize regions of viral envelope glycoproteins that play a role in receptor binding or other aspects of virus entry. To address whether this is a necessary feature of a neutralizing antibody, we identified the V4 region of the gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) as a sequence that is tolerant of drastic change and thus appears to play a negligible role in envelope glycoprotein function. An artificial epitope tag was inserted into the V4 region without a significant effect on virus entry or neutralization by antibodies that recognize HIV-1 envelope glycoprotein sequences. An antibody directed against the artificial epitope tag was able to neutralize the modified, but not the wild-type, HIV-1. Thus, the specific target of a neutralizing antibody need not contribute functionally to the process of virus entry.

scholarly journals Spontaneous Mutation at Amino Acid 544 of the Ebola Virus Glycoprotein Potentiates Virus Entry and Selection in Tissue Culture

2017 ◽  
Vol 91 (15) ◽  
Author(s):  
John B. Ruedas ◽  
Jason T. Ladner ◽  
Chelsea R. Ettinger ◽  
Suryaram Gummuluru ◽  
Gustavo Palacios ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Experimental Evidence ◽  
Ebola Virus ◽  
Virus Entry ◽  
Spontaneous Mutation ◽  
Culture Conditions ◽  
Surface Glycoprotein ◽  
Virus Growth ◽  
Content Type ◽  
Zaire Ebolavirus

ABSTRACT Ebolaviruses have a surface glycoprotein (GP1,2) that is required for virus attachment and entry into cells. Mutations affecting GP1,2 functions can alter virus growth properties. We generated a recombinant vesicular stomatitis virus encoding Ebola virus Makona variant GP1,2 (rVSV-MAK-GP) and observed emergence of a T544I mutation in the Makona GP1,2 gene during tissue culture passage in certain cell lines. The T544I mutation emerged within two passages when VSV-MAK-GP was grown on Vero E6, Vero, and BS-C-1 cells but not when it was passaged on Huh7 and HepG2 cells. The mutation led to a marked increase in virus growth kinetics and conferred a robust growth advantage over wild-type rVSV-MAK-GP on Vero E6 cells. Analysis of complete viral genomes collected from patients in western Africa indicated that this mutation was not found in Ebola virus clinical samples. However, we observed the emergence of T544I during serial passage of various Ebola Makona isolates on Vero E6 cells. Three independent isolates showed emergence of T544I from undetectable levels in nonpassaged virus or virus passaged once to frequencies of greater than 60% within a single passage, consistent with it being a tissue culture adaptation. Intriguingly, T544I is not found in any Sudan, Bundibugyo, or Tai Forest ebolavirus sequences. Furthermore, T544I did not emerge when we serially passaged recombinant VSV encoding GP1,2 from these ebolaviruses. This report provides experimental evidence that the spontaneous mutation T544I is a tissue culture adaptation in certain cell lines and that it may be unique for the species Zaire ebolavirus. IMPORTANCE The Ebola virus (Zaire) species is the most lethal species of all ebolaviruses in terms of mortality rate and number of deaths. Understanding how the Ebola virus surface glycoprotein functions to facilitate entry in cells is an area of intense research. Recently, three groups independently identified a polymorphism in the Ebola glycoprotein (I544) that enhanced virus entry, but they did not agree in their conclusions regarding its impact on pathogenesis. Our findings here address the origins of this polymorphism and provide experimental evidence showing that it is the result of a spontaneous mutation (T544I) specific to tissue culture conditions, suggesting that it has no role in pathogenesis. We further show that this mutation may be unique to the species Zaire ebolavirus, as it does not occur in Sudan, Bundibugyo, and Tai Forest ebolaviruses. Understanding the mechanism behind this mutation can provide insight into functional differences that exist in culture conditions and among ebolavirus glycoproteins.

scholarly journals N-Terminal Domain of Borna Disease Virus G (p56) Protein Is Sufficient for Virus Receptor Recognition and Cell Entry

2001 ◽  
Vol 75 (15) ◽  
pp. 7078-7085 ◽  
Author(s):  
Mar Perez ◽  
Michiko Watanabe ◽  
Michael A. Whitt ◽  
Juan Carlos de la Torre
Keyword(s):  
Amino Acids ◽  
G Protein ◽  
Disease Virus ◽  
Fluorescent Protein ◽  
Virus Entry ◽  
Surface Glycoprotein ◽  
Terminal Part ◽  
Borna Disease Virus ◽  
Receptor Recognition ◽  
Borna Disease

ABSTRACT Borna disease virus (BDV) surface glycoprotein (GP) (p56) has a predicted molecular mass of 56 kDa. Due to extensive posttranslational glycosylation the protein migrates as a polypeptide of 84 kDa (gp84). The processing of gp84 by the cellular protease furin generates gp43, which corresponds to the C-terminal part of gp84. Both gp84 and gp43 have been implicated in viral entry involving receptor-mediated endocytosis and pH-dependent fusion. We have investigated the domains of BDV p56 involved in virus entry. For this, we used a pseudotype approach based on a recently developed recombinant vesicular stomatitis virus (VSV) in which the gene for green fluorescent protein was substituted for the VSV G protein gene (VSVΔG*). Complementation of VSVΔG* with BDV p56 resulted in infectious VSVΔG* pseudotypes that contained both BDV gp84 and gp43. BDV-VSV chimeric GPs that contained the N-terminal 244 amino acids of BDV p56 and amino acids 421 to 511 of VSV G protein were efficiently incorporated into VSVΔG* particles, and the resulting pseudotype virions were neutralized by BDV-specific antiserum. These findings indicate that the N-terminal part of BDV p56 is sufficient for receptor recognition and virus entry.

scholarly journals Targeting the Proteolytic Processing of the Viral Glycoprotein Precursor Is a Promising Novel Antiviral Strategy against Arenaviruses

2009 ◽  
Vol 84 (1) ◽  
pp. 573-584 ◽  
Author(s):  
Jillian M. Rojek ◽  
Giulia Pasqual ◽  
Ana B. Sanchez ◽  
Ngoc-Thao Nguyen ◽  
Juan-Carlos de la Torre ◽  
...  
Keyword(s):  
Reverse Genetics ◽  
Drug Effects ◽  
Virus Production ◽  
Antiviral Effect ◽  
Proteolytic Processing ◽  
Viral Envelope ◽  
Viral Escape ◽  
Viral Glycoprotein ◽  
Glycoprotein Precursor ◽  
Viral Spread

ABSTRACT A crucial step in the arenavirus life cycle is the biosynthesis of the viral envelope glycoprotein (GP) responsible for virus attachment and entry. Processing of the GP precursor (GPC) by the cellular proprotein convertase site 1 protease (S1P), also known as subtilisin-kexin-isozyme 1 (SKI-1), is crucial for cell-to-cell propagation of infection and production of infectious virus. Here, we sought to evaluate arenavirus GPC processing by S1P as a target for antiviral therapy using a recently developed peptide-based S1P inhibitor, decanoyl (dec)-RRLL-chloromethylketone (CMK), and the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV). To control for off-target effects of dec-RRLL-CMK, we employed arenavirus reverse genetics to introduce a furin recognition site into the GPC of LCMV. The rescued mutant virus grew to normal titers, and the processing of its GPC critically depended on cellular furin, but not S1P. Treatment with the S1P inhibitor dec-RRLL-CMK resulted in specific blocking of viral spread and virus production of LCMV. Combination of the protease inhibitor with ribavirin, currently used clinically for treatment of human arenavirus infections, resulted in additive drug effects. In cells deficient in S1P, the furin-dependent LCMV variant established persistent infection, whereas wild-type LCMV underwent extinction without the emergence of S1P-independent escape variants. Together, the potent antiviral activity of an inhibitor of S1P-dependent GPC cleavage, the additive antiviral effect with ribavirin, and the low probability of emergence of S1P-independent viral escape variants make S1P-mediated GPC processing by peptide-derived inhibitors a promising strategy for the development of novel antiarenaviral drugs.

scholarly journals Antibody Binding in Proximity to the Receptor/Glycoprotein Complex Leads to a Basal Level of Virus Neutralization

2007 ◽  
Vol 81 (16) ◽  
pp. 8809-8813 ◽  
Author(s):  
Xinzhen Yang ◽  
Inna Lipchina ◽  
Michelle Lifton ◽  
Liping Wang ◽  
Joseph Sodroski
Keyword(s):  
Conformational Changes ◽  
Steric Hindrance ◽  
Virus Entry ◽  
Receptor Protein ◽  
Receptor Complex ◽  
Retroviral Infection ◽  
Enveloped Viruses ◽  
Glycoprotein Complex ◽  
Additional Support ◽  
Avian Sarcoma

ABSTRACT Hypothetically, antibodies may neutralize enveloped viruses by diverse mechanisms, such as disruption of receptor binding, interference with conformational changes required for virus entry, steric hindrance, or virus aggregation. Here, we demonstrate that retroviral infection mediated by the avian sarcoma-leukosis virus (ASLV-A) envelope glycoproteins can be neutralized by an antibody directed against a functionally unimportant component of a chimeric receptor protein. Thus, the binding of an antibody in proximity to the retroviral envelope glycoprotein-receptor complex, without binding to the entry machinery itself, results in neutralization. This finding provides additional support for the hypothesis that steric hindrance is sufficient for antibody-mediated neutralization of retroviruses.

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 Two Sides to Every Story: Herpes Simplex Type-1 Viral Glycoproteins gB, gD, gH/gL, gK, and Cellular Receptors Function as Key Players in Membrane Fusion

Viruses ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1849
Author(s):  
Nithya Jambunathan ◽  
Carolyn M. Clark ◽  
Farhana Musarrat ◽  
Vladimir N. Chouljenko ◽  
Jared Rudd ◽  
...  
Keyword(s):  
Herpes Simplex ◽  
Membrane Fusion ◽  
Virus Entry ◽  
Viral Envelope ◽  
Critical Determinant ◽  
Cellular Receptors ◽  
Disease Spectrum ◽  
Viral Glycoproteins ◽  
Hsv 1

Herpes simplex virus type-1 (HSV-1) and type-2 (HSV-2) are prototypical alphaherpesviruses that are characterized by their unique properties to infect trigeminal and dorsal root ganglionic neurons, respectively, and establish life-long latent infections. These viruses initially infect mucosal epithelial tissues and subsequently spread to neurons. They are associated with a significant disease spectrum, including orofacial and ocular infections for HSV-1 and genital and neonatal infections for HSV-2. Viral glycoproteins within the virion envelope bind to specific cellular receptors to mediate virus entry into cells. This is achieved by the fusion of the viral envelope with the plasma membrane. Similarly, viral glycoproteins expressed on cell surfaces mediate cell-to-cell fusion and facilitate virus spread. An interactive complex of viral glycoproteins gB, gD/gH/gL, and gK and other proteins mediate these membrane fusion phenomena with glycoprotein B (gB), the principal membrane fusogen. The requirement for the virion to enter neuronal axons suggests that the heterodimeric protein complex of gK and membrane protein UL20, found only in alphaherpesviruses, constitute a critical determinant for neuronal entry. This hypothesis was substantiated by the observation that a small deletion in the amino terminus of gK prevents entry into neuronal axons while allowing entry into other cells via endocytosis. Cellular receptors and receptor-mediated signaling synergize with the viral membrane fusion machinery to facilitate virus entry and intercellular spread. Unraveling the underlying interactions among viral glycoproteins, envelope proteins, and cellular receptors will provide new innovative approaches for antiviral therapy against herpesviruses and other neurotropic viruses.

scholarly journals Characterization of Borna disease virus p56 protein, a surface glycoprotein involved in virus entry.

1997 ◽  
Vol 71 (4) ◽  
pp. 3208-3218 ◽  
Author(s):  
D Gonzalez-Dunia ◽  
B Cubitt ◽  
F A Grasser ◽  
J C de la Torre
Keyword(s):  
Disease Virus ◽  
Virus Entry ◽  
Protein A ◽  
Surface Glycoprotein ◽  
Borna Disease Virus ◽  
Borna Disease
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