Related Experiment Videos
RSV entry inhibitors block F-protein mediated fusion with model membranes
Vladimir Razinkov1, Clayton Huntley, George Ellestad
1Department of Biological Chemistry, Wyeth Research, Pearl River, NY 10965, USA.
Abstract:
RSV fusion is mediated by F-protein, a major viral surface glycoprotein. CL-309623, a specific inhibitor of RSV, interacts tightly with F-protein, which results in a hydrophobic environment at the binding site. The binding is selective for F-protein and does not occur with G-protein, a surface glycoprotein that facilitates the binding of RSV to target cells, or with lipid membranes at concentrations in the sub-millimolar range. Using an assay based on the relief of self-quenching of octadecyl rhodamine (R18) incorporated in the RSV envelope, we show that the virus fuses efficiently with large unilamellar vesicles containing cholesterol, in the absence of specific receptor analogs. Fusion of cp-52, a mutant virus lacking the G and SH surface glycoproteins, with vesicles is inhibited by CL-309623 and RFI-641 due to specific interactions of the inhibitor(s) with the fusion protein. Both virus-vesicle and virus-cell fusion are inhibited with equal potency. The formation of the binary complex of CL-309623 with F-protein in its native state, resulting in the inhibition of fusion and entry of virus, is a prerequisite for the observed anti-RSV activity in cell cultures.
Insights
CL-309623, a respiratory syncytial virus (RSV) inhibitor, targets the F-protein, blocking viral fusion and entry. This specific interaction prevents RSV infection, offering a potential therapeutic strategy against RSV.
Area of Science:
- Virology
- Molecular Biology
- Drug Discovery
Background:
- Respiratory syncytial virus (RSV) fusion is primarily mediated by its F-protein, a key viral surface glycoprotein.
- Understanding the F-protein's role is crucial for developing antiviral therapies against RSV.
Purpose of the Study:
- To investigate the mechanism of action of CL-309623, a specific inhibitor of RSV fusion.
- To determine the selectivity and potency of CL-309623 in inhibiting RSV F-protein interactions and viral fusion.
Main Methods:
- Utilized an octadecyl rhodamine (R18) assay to monitor RSV envelope fusion with large unilamellar vesicles.
- Assessed the inhibitory effects of CL-309623 and RFI-641 on the fusion of wild-type and mutant RSV (cp-52) with vesicles.
- Evaluated the binding selectivity of CL-309623 for F-protein over G-protein and lipid membranes.
Main Results:
- CL-309623 binds specifically to the RSV F-protein in a hydrophobic environment, inhibiting viral fusion.
- The inhibitor demonstrated selective binding to F-protein, with no significant interaction with G-protein or lipid membranes.
- CL-309623 effectively inhibited fusion of both virus-vesicle and virus-cell systems with equal potency.
- Inhibition of fusion by CL-309623 was observed even with a mutant virus lacking G and SH glycoproteins, confirming F-protein as the target.
Conclusions:
- The formation of a CL-309623-F-protein binary complex is essential for its anti-RSV activity.
- CL-309623's specific interaction with the F-protein effectively blocks RSV fusion and viral entry.
- These findings highlight CL-309623 as a promising therapeutic agent for combating RSV infections.