scholarly journals Structurally conserved domains between flavivirus and alphavirus fusion glycoproteins contribute to replication in mammals and infectious virion production.

2021 ◽  
Author(s):  
Margarita V. Rangel ◽  
Nicholas Catanzaro ◽  
Sara A. Thannickal ◽  
Kelly A. Crotty ◽  
Maria G. Noval ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Envelope Glycoprotein ◽  
Fusion Proteins ◽  
Yellow Fever Virus ◽  
Class Ii ◽  
Virion Assembly ◽  
Infectious Virion ◽  
Virion Production ◽  
Flavivirus Infection

Alphaviruses and flaviviruses have class II fusion glycoproteins that are essential for virion assembly and infectivity. Importantly, the tip of domain II is structurally conserved between the alphavirus and flavivirus fusion proteins, yet whether these structural similarities between virus families translate to functional similarities is unclear. Using in vivo evolution of Zika virus (ZIKV), we identified several novel emerging variants including an envelope glycoprotein variant in b-strand c (V114M) of domain II. We have previously shown that the analogous b-strand c and the ij loop, located in the tip of domain II of the alphavirus E1 glycoprotein, are important for infectivity. This led us to hypothesize that flavivirus E b-strand c also contributes to flavivirus infection. We generated this ZIKV glycoprotein ­variant and found that while it had little impact on infection in mosquitoes, it reduced replication in human cells and mice, and increased virus sensitivity to ammonium chloride, as seen for alphaviruses. In light of these results and given our alphavirus ij loop studies, we mutated a conserved alanine at the tip of the flavivirus ij loop to valine to test its effect on ZIKV infectivity. Interestingly, this mutation inhibited infectious virion production of ZIKV and yellow fever virus, but not West Nile virus. Together, these studies show that structurally analogous residues in the alphavirus and flavivirus class II fusion proteins contribute to virus infection in vivo and highlight these shared domains as targets for broad-spectrum arbovirus therapies.

Structurally conserved domains between flavivirus and alphavirus fusion glycoproteins contribute to replication and infectious virion production.

2021 ◽  
Author(s):  
Margarita V. Rangel ◽  
Nicholas Catanzaro ◽  
Sara A. Thannickal ◽  
Kelly A. Crotty ◽  
Maria G. Noval ◽  
...  
Keyword(s):  
Life Cycle ◽  
Fusion Proteins ◽  
Molecular Mechanisms ◽  
Yellow Fever Virus ◽  
Class Ii ◽  
Global Public Health ◽  
Virion Assembly ◽  
Infectious Virion ◽  
Virion Production

Alphaviruses and flaviviruses have class II fusion glycoproteins that are essential for virion assembly and infectivity. Importantly, the tip of domain II is structurally conserved between the alphavirus and flavivirus fusion proteins, yet whether these structural similarities between virus families translate to functional similarities is unclear. Using in vivo evolution of Zika virus (ZIKV), we identified several novel emerging variants including an envelope glycoprotein variant in β-strand c (V114M) of domain II. We have previously shown that the analogous β-strand c and the ij loop, located in the tip of domain II of the alphavirus E1 glycoprotein, are important for infectivity. This led us to hypothesize that flavivirus E β-strand c also contributes to flavivirus infection. We generated this ZIKV glycoprotein variant and found that while it had little impact on infection in mosquitoes, it reduced replication in human cells and mice, and increased virus sensitivity to ammonium chloride, as seen for alphaviruses. In light of these results and given our alphavirus ij loop studies, we mutated a conserved alanine at the tip of the flavivirus ij loop to valine to test its effect on ZIKV infectivity. Interestingly, this mutation inhibited infectious virion production of ZIKV and yellow fever virus, but not West Nile virus. Together, these studies show that shared domains of the alphavirus and flavivirus class II fusion glycoproteins harbor structurally analogous residues that are functionally important and contribute to virus infection in vivo. Importance Arboviruses are a significant global public health threat, yet there are no antivirals targeting these viruses. This problem is in part due to our lack of knowledge on the molecular mechanisms involved in the arbovirus life cycle. In particular, virus entry and assembly are essential processes in the virus life cycle and steps that can be targeted for the development of antiviral therapies. Therefore, understanding common, fundamental mechanisms used by different arboviruses for entry and assembly is essential. In this study, we show that flavivirus and alphavirus residues located in structurally conserved and analogous regions of the class II fusion proteins contribute to common mechanisms of entry, dissemination, and infectious virion production. These studies highlight how class II fusion proteins function and provide novel targets for development of antivirals.

scholarly journals Differential Cholesterol Binding by Class II Fusion Proteins Determines Membrane Fusion Properties

2008 ◽  
Vol 82 (18) ◽  
pp. 9245-9253 ◽  
Author(s):  
M. Umashankar ◽  
Claudia Sánchez-San Martín ◽  
Maofu Liao ◽  
Brigid Reilly ◽  
Alice Guo ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Membrane Fusion ◽  
Fusion Proteins ◽  
Sindbis Virus ◽  
Semliki Forest Virus ◽  
Yellow Fever Virus ◽  
Class Ii ◽  
Binding Properties ◽  
Functional Differences ◽  
Cholesterol Binding

ABSTRACT The class II fusion proteins of the alphaviruses and flaviviruses mediate virus infection by driving the fusion of the virus membrane with that of the cell. These fusion proteins are triggered by low pH, and their structures are strikingly similar in both the prefusion dimer and the postfusion homotrimer conformations. Here we have compared cholesterol interactions during membrane fusion by these two groups of viruses. Using cholesterol-depleted insect cells, we showed that fusion and infection by the alphaviruses Semliki Forest virus (SFV) and Sindbis virus were strongly promoted by cholesterol, with similar sterol dependence in laboratory and field isolates and in viruses passaged in tissue culture. The E1 fusion protein from SFV bound cholesterol, as detected by labeling with photocholesterol and by cholesterol extraction studies. In contrast, fusion and infection by numerous strains of the flavivirus dengue virus (DV) and by yellow fever virus 17D were cholesterol independent, and the DV fusion protein did not show significant cholesterol binding. SFV E1 is the first virus fusion protein demonstrated to directly bind cholesterol. Taken together, our results reveal important functional differences conferred by the cholesterol-binding properties of class II fusion proteins.

scholarly journals Genetic control of T cell responsiveness to the Friend murine leukemia virus envelope antigen. Identification of class II loci of the H-2 as immune response genes.

1988 ◽  
Vol 168 (5) ◽  
pp. 1587-1605 ◽  
Author(s):  
M Miyazawa ◽  
J Nishio ◽  
B Chesebro
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Envelope Glycoprotein ◽  
Envelope Protein ◽  
Class Ii ◽  
Virus Envelope ◽  
Mhc Molecules ◽  
Murine Leukemia

T cells primed specifically for the envelope glycoprotein of Friend murine leukemia helper virus (F-MuLV) were prepared by immunizing mice with a recombinant vaccinia virus that expressed the entire env gene of F-MuLV. Significant proliferative responses of F-MuLV envelope-specific, H-2a/b T cells were observed when the T cells were stimulated with antigen-pulsed peritoneal exudate cells (PEC) having the b allele at the K, A beta, A alpha, and E beta loci of the H-2. On the other hand, PEC having only the kappa allele at these loci did not induce the envelope-specific T cell proliferation, even when the PEC had the b allele at the E alpha, S, or D loci. F-MuLV envelope-specific proliferation of H-2a/b T cells under the stimulation of antigen-pulsed, H-2a/b PEC was specifically blocked with anti-I-Ab and anti-I-Ek mAbs but not with anti-Kb, anti-Kk, or anti-I-Ak mAbs. Moreover, (B10.MBR x A/WySn)F1 mice that have the b allele only at the K locus but not in I-A subregion were nonresponders to the envelope glycoprotein, and the bm12 mutation at the A beta locus completely abolished the T cell responsiveness to this antigen. These results indicate that proliferative T cells recognize a limited number of epitopes on F-MuLV envelope protein in the context of I-Ab, hybrid I-Ak/b, and/or hybrid I-Ek/b class II MHC molecules but fail to recognize the same envelope protein in the context of I-Ak or I-Ek molecules. This influence of the H-2I region on T cell recognition of the envelope glycoprotein appeared to control in vivo induction of protective immunity against Friend virus complex after immunization with the vaccinia-F-MuLV env vaccine. Thus, these results provide, for the first time, direct evidence for Ir gene-controlled responder/nonresponder phenotypes influencing the immune response to a pathogenic virus of mice.

Improved Bioavailability of Oxcarbazepine, a BCS class II drug by Centrifugal Melt Spinning: In-vitro and in-vivo Implications

2021 ◽  
pp. 120775
Author(s):  
Sidra Nasir ◽  
Amjad Hussain ◽  
Nasir Abbas ◽  
Nadeem Irfan Bukhari ◽  
Fahad Hussain ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Class Ii ◽  
Bcs Class Ii

scholarly journals Thermostability Engineering of a Class II Pyruvate Aldolase from Escherichia coli by in Vivo Folding Interference

2021 ◽  
Vol 9 (15) ◽  
pp. 5430-5436
Author(s):  
Sandra Bosch ◽  
Esther Sanchez-Freire ◽  
María Luisa del Pozo ◽  
Morana C̆esnik ◽  
Jaime Quesada ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Class Ii

scholarly journals Overexpressing the HD-Zip class II transcription factor EcHB1 from Eucalyptus camaldulensis increased the leaf photosynthesis and drought tolerance of Eucalyptus

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Keisuke Sasaki ◽  
Yuuki Ida ◽  
Sakihito Kitajima ◽  
Tetsu Kawazu ◽  
Takashi Hibino ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Leaf Area ◽  
Leucine Zipper ◽  
Eucalyptus Grandis ◽  
Eucalyptus Camaldulensis ◽  
Class Ii ◽  
Cell Multiplication ◽  
Leaf Photosynthesis ◽  
Unit Leaf

Abstract Alteration in the leaf mesophyll anatomy by genetic modification is potentially a promising tool for improving the physiological functions of trees by improving leaf photosynthesis. Homeodomain leucine zipper (HD-Zip) transcription factors are candidates for anatomical alterations of leaves through modification of cell multiplication, differentiation, and expansion. Full-length cDNA encoding a Eucalyptus camaldulensis HD-Zip class II transcription factor (EcHB1) was over-expressed in vivo in the hybrid Eucalyptus GUT5 generated from Eucalyptus grandis and Eucalyptus urophylla. Overexpression of EcHB1 induced significant modification in the mesophyll anatomy of Eucalyptus with enhancements in the number of cells and chloroplasts on a leaf-area basis. The leaf-area-based photosynthesis of Eucalyptus was improved in the EcHB1-overexpression lines, which was due to both enhanced CO2 diffusion into chloroplasts and increased photosynthetic biochemical functions through increased number of chloroplasts per unit leaf area. Additionally, overexpression of EcHB1 suppressed defoliation and thus improved the growth of Eucalyptus trees under drought stress, which was a result of reduced water loss from trees due to the reduction in leaf area with no changes in stomatal morphology. These results gave us new insights into the role of the HD-Zip II gene.

scholarly journals Measuring ligand-dependent and ligand-independent interactions between nuclear receptors and associated proteins using Bioluminescence Resonance Energy Transfer (BRET2)

2006 ◽  
Vol 4 (1) ◽  
pp. nrs.04021 ◽  
Author(s):  
Kristen L. Koterba ◽  
Brian G. Rowan
Keyword(s):  
Energy Transfer ◽  
Protein Interactions ◽  
Fusion Proteins ◽  
Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Renilla Luciferase ◽  
Receptor Protein ◽  
Protein Protein Interactions

Bioluminescent resonance energy transfer (BRET2) is a recently developed technology for the measurement of protein-protein interactions in a live, cell-based system. BRET2 is characterized by the efficient transfer of excited energy between a bioluminescent donor molecule (Renilla luciferase) and a fluorescent acceptor molecule (a mutant of Green Fluorescent Protein (GFP2)). The BRET2 assay offers advantages over fluorescence resonance energy transfer (FRET) because it does not require an external light source thereby eliminating problems of photobleaching and autoflourescence. The absence of contamination by light results in low background that permits detection of very small changes in the BRET2 signal. BRET2 is dependent on the orientation and distance between two fusion proteins and therefore requires extensive preliminary standardization experiments to conclude a positive BRET2 signal independent of variations in protein titrations and arrangement in tertiary structures. Estrogen receptor (ER) signaling is modulated by steroid receptor coactivator 1 (SRC-1). To establish BRET2 in a ligand inducible system we used SRC-1 as the donor moiety and ER as the acceptor moiety. Expression and functionality of the fusion proteins were assessed by transient transfection in HEK-293 cells followed by Western blot analysis and measurement of ER-dependent reporter gene activity. These preliminary determinations are required prior to measuring nuclear receptor protein-protein interactions by BRET2. This article describes in detail the BRET2 methodology for measuring interaction between full-length ER and coregulator proteins in real-time, in an in vivo environment.

A rapid and reliable in vivo method for anti-GPLA (class I and class II antigens) antibody titration and GPLA typing

1983 ◽  
Vol 59 (2) ◽  
pp. 205-215 ◽  
Author(s):  
Thérèse Neveu ◽  
Michèle Lefroit-Joliy ◽  
Guy André Voisin
Keyword(s):  
Class Ii ◽  
Class I ◽  
Class Ii Antigens
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