RSV F evolution escapes some monoclonal antibodies but does not strongly erode neutralization by human polyclonal sera

Vaccines and monoclonal antibodies targeting the respiratory syncytial virus (RSV) fusion protein (F) have recently begun to be widely used to protect infants and high-risk adults. Some other viral proteins evolve to erode polyclonal antibody neutralization and escape individual monoclonal antibodies. However, the impact of RSV F evolution on antibody neutralization is not yet thoroughly understood. Here, we develop an experimental system for measuring neutralization titers against RSV F using pseudotyped lentiviral particles. This system is easily adaptable to evaluate neutralization of relevant clinical strains. We apply this system to demonstrate that the natural evolution of RSV F leads to escape from some monoclonal antibodies, but at most modestly affects neutralization by polyclonal serum antibodies. Overall, our work sheds light on RSV antigenic evolution and describes a tool to measure the ability of antibodies and sera to neutralize contemporary RSV strains.IMPORTANCEWe describe an efficient approach to measure how antibodies inhibit infection by historical and recent human strains of respiratory syncytial virus (RSV). This approach is useful for understanding how viral evolution affects antibody immunity. We apply this approach to demonstrate that RSV evolution can escape some monoclonal antibodies, but polyclonal serum antibodies are less impacted by viral evolution. This information is relevant given the recent development of RSV preventative measures, including monoclonal antibodies and vaccines.