Viral Fusion Protein Activation
Viral Fusion Protein Activation - Related Videos
02:45
Assessment of Viral Fusion Inhibitors Using a Cre-Inducible Fluorescent Reporter
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2026
Source: Esposito, A. M.,et al. High-throughput Cre-Lox Activated Viral Membrane Fusion Assay to Identify Inhibitors of HIV-1 Viral Membrane Fusion. J. Vis. Exp. (2018)This video demonstrates a co-culture fluorescent assay to monitor cell-to-cell viral transmission. The assay uses a red-to-green reporter cassette to visualize viral membrane fusion and evaluate the efficacy of test compounds in blocking viral entry.
02:38
An Assay to Evaluate the Effect of Test Compounds on Viral Entry and Fusion in Host Cells
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2025
This video demonstrates an assay to evaluate antiviral agents that target specific steps of the viral entry into host cells and fusion with the endosome. The cells are incubated at a low temperature and then infected with HCV. The low temperature permits viral binding to host cells but inhibits internalization via endocytosis. The test antiviral compound is added, and the cells are incubated at physiological temperature. This shift to a higher temperature facilitates viral entry and allows...
14:59
Method for Measurement of Viral Fusion Kinetics at the Single Particle Level
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Cited by 11 •
2009
We present an in vitro, two-color fluorescence assay to visualize the fusion of single virus particles with a fluid target bilayer. By labeling viral particles with fluorophores that differentially stain the viral membrane and its interior, we are able to monitor the kinetics of hemifusion and pore formation.
07:22
A High-throughput Cre-Lox Activated Viral Membrane Fusion Assay to Identify Inhibitors of HIV-1 Viral Membrane Fusion
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Cited by 8 •
2018
We describe a cell-based assay to report on HIV-1 fusion via the expression of green fluorescent protein detectable by flow cytometry or fluorescence microscopy. It can be used to test inhibitors of viral entry (specifically at the fusion step) in cell-free and cell-to-cell infection systems.
05:13
Isolation of Proteins from Viral DNA-protein Complexes
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2026
Source: Dembowski, J. A., et al. Purification of Viral DNA for the Identification of Associated Viral and Cellular Proteins. J. Vis. Exp. (2017).This video demonstrates the isolation of protein–viral DNA complexes from cell nuclei using click chemistry and magnetic bead purification. The protocol involves labeling viral genomes with alkyne-modified nucleotides, biotinylation via a click reaction, and binding to streptavidin-coated magnetic beads. Following washing and heat elution, the purified...
FAQs
These triggers act as biochemical signals that shift the protein away from its metastable prefusion arrangement. Receptor binding can initiate activation at the host-cell surface, whereas proteolytic cleavage or acidic pH can provide additional requirements, depending on the virus. Some fusion proteins therefore respond to a combination of triggers rather than to one signal alone.
Activation rearranges the fusion protein so that previously constrained hydrophobic fusion regions become exposed or repositioned. These regions can then insert into the target membrane, creating a physical connection between the viral protein and host bilayer. The resulting configuration brings the two membranes into close proximity and supports progression toward fusion.
Trigger requirements determine where and under what conditions fusion can proceed. A protein may require receptor binding, cleavage, acidic pH, or a combination before its hydrophobic regions become properly positioned. These biochemical constraints influence viral entry and can help explain host-range determinants by linking activation conditions to the cells or compartments a virus can use.
A typical conceptual sequence begins with an activating signal, followed by structural rearrangement, exposure or repositioning of hydrophobic fusion regions, membrane insertion, and movement of the two bilayers toward one another. Fusion assays can be designed around this sequence to examine whether activation produces membrane merging and to distinguish activation from earlier binding events.
Fusion assays provide an experimental context for testing whether an activated viral fusion protein can drive merger of viral and host-cell membranes. By examining responses to relevant triggers such as receptor engagement, proteolytic cleavage, or acidic pH, researchers can relate biochemical activation conditions to membrane-fusion outcomes and compare how different proteins behave.
Activation studies identify structural transitions that are required before membranes merge, creating points for entry-inhibitor development. They also inform vaccine design by supporting stabilized prefusion conformations, which preserve the protein arrangement present before activation. Together, these applications connect mechanistic biochemistry with strategies to block viral entry or present relevant viral structures.