Respiratory syncytial virus fusion protein (RSV F protein) (RSV F)

The Respiratory syncytial virus (RSV) fusion protein (F protein) is a critical surface glycoprotein that mediates viral entry by facilitating the fusion of the viral envelope with the host cell membrane (McLellan et al., 2013, Science). Antigenic site II is a highly conserved, conformational epitope located on the F protein that is recognized by potent neutralizing antibodies (Graham, 2017, Immunol Rev). Unlike some other epitopes, site II is present on both the metastable pre-fusion and the stable post-fusion conformations of the F protein, making it a reliable target for immunoprophylaxis (UniProt P03420). The humanized monoclonal antibody palivizumab specifically binds to this site, sterically inhibiting the structural transitions required for the fusion process (Johnson et al., 1997, J Infect Dis). This interaction effectively neutralizes the virus and prevents the formation of syncytia, which are characteristic of RSV-induced lung pathology (PubMed: 9389745). Clinical use of site II-targeting agents has significantly reduced hospitalizations in high-risk infants, such as those born prematurely or with congenital heart disease (NIH, 2023). However, the emergence of viral escape mutants with amino acid substitutions in site II remains a significant therapeutic challenge and requires continuous monitoring (PubMed: 25231621). Understanding the structural biology of site II has been foundational for the development of both passive immunization strategies and structure-based vaccine design.

Other names

Antigenic site IIRSV F protein site IISite ARSV fusion glycoproteinRespiratory syncytial virus fusion protein, antigenic site II

Inhibition of viral-host cell membrane fusion by binding to a conserved epitope (site II) on the F protein, preventing the conformational change from pre-fusion to post-fusion states.