How Mutations in the Respiratory Syncytial Virus Fusion Protein Affect Fusion Activity and Antibody Binding
Additional Funding Sources
This project was made possible by the NSF Idaho EPSCoR Program and by the National Science Foundation under Award No. OIA-1757324, an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under Grant No. P20GM103408, and the Brian and Gayle Hill Undergraduate Research Fellowship, College of Science, University of Idaho. The project was additionally supported by the Idaho EPSCoR Track-II Program through the National Science Foundation under Award No. OIA-1736253.
Abstract
Monoclonal antibodies are important therapeutics for viral infections; however viruses can mutate to avoid being bound by these antibodies. This project focusses on the monoclonal antibody motavizumab and its interaction with the Respiratory Syncytial Virus Fusion (RSV-F) glycoprotein. RSV-F mediates fusion of the virus lipid bilayer with that of the host cell during entry of the virus into a cell. This causes infected cells to fuse with other cells, causing syncytia to form. Motavizumab blocks these functions of RSV-F. The current literature has identified one mutation in the RSV-F motavizumab binding pocket that allows the virus to escape the neutralizing effects of motavizumab. Our group performed molecular modeling to identify additional potential escape variants. Some of the predicted escape mutants not only evaded neutralization by motavizumab, but also had varying growth rates and levels of syncytia formation. This project expands on those observations by studying RSV-F in isolation rather than looking at the entire virus. The RSV-F variant genes were isolated and placed in a backbone plasmid to be used in transient transfections. The RSV-F expressing transfected cells were imaged to determine the variant's relative fusion activity. After imaging, the cells were lysed to test for amount of RSV-F protein present and the ability of those RSV-F variants to bind to motavizumab. Through these methods, it was found that the mutants expressed a wide range of fusion activity as well as motavizumab binding. These studies will be important in understanding how RSV can evolve to avoid antibody binding while retaining fusion activity and will also provide rapid screens for evaluating antibody binding and fusion of potential escape variants.
How Mutations in the Respiratory Syncytial Virus Fusion Protein Affect Fusion Activity and Antibody Binding
Monoclonal antibodies are important therapeutics for viral infections; however viruses can mutate to avoid being bound by these antibodies. This project focusses on the monoclonal antibody motavizumab and its interaction with the Respiratory Syncytial Virus Fusion (RSV-F) glycoprotein. RSV-F mediates fusion of the virus lipid bilayer with that of the host cell during entry of the virus into a cell. This causes infected cells to fuse with other cells, causing syncytia to form. Motavizumab blocks these functions of RSV-F. The current literature has identified one mutation in the RSV-F motavizumab binding pocket that allows the virus to escape the neutralizing effects of motavizumab. Our group performed molecular modeling to identify additional potential escape variants. Some of the predicted escape mutants not only evaded neutralization by motavizumab, but also had varying growth rates and levels of syncytia formation. This project expands on those observations by studying RSV-F in isolation rather than looking at the entire virus. The RSV-F variant genes were isolated and placed in a backbone plasmid to be used in transient transfections. The RSV-F expressing transfected cells were imaged to determine the variant's relative fusion activity. After imaging, the cells were lysed to test for amount of RSV-F protein present and the ability of those RSV-F variants to bind to motavizumab. Through these methods, it was found that the mutants expressed a wide range of fusion activity as well as motavizumab binding. These studies will be important in understanding how RSV can evolve to avoid antibody binding while retaining fusion activity and will also provide rapid screens for evaluating antibody binding and fusion of potential escape variants.