[Screening of RSV post-F-specific monoclonal antibodies for vaccine conformational evaluation]

Respiratory syncytial virus (respiratory syncytial virus, RSV) is a leading cause of lower respiratory tract infections in infants and young children. The viral fusion (F) protein, which mediates viral entry into host cells, adopts two distinct conformations: the pre-fusion (pre-F) and post-fusion (post-F). The epitopes most sensitive to neutralizing antibodies are exclusively present on the pre-F conformation, making it a major focus of current vaccine and antibody development. However, the pre-F conformation is metastable and undergoes an irreversible transition to the post-F conformation upon membrane fusion or spontaneous triggering. Therefore, antibodies specifically recognize the post-F conformation can be used to quantify the post-F content in vaccine products, thereby assessing the conformational stability and purity. In this study, we established a rabbit-derived single B-cell antibody platform covering the entire workflow from immunization to antibody screening. Using this platform, we successfully obtained two rabbit monoclonal antibodies with high specificity and affinity for RSV post-F protein. Epitope mapping revealed that both antibodies bound to regions outside of site I. Preliminary validation demonstrated the utility of these antibodies in detecting the post-F protein in vaccine drug substance, suggesting their potential for assessing antigen conformational stability and purity. This work provides important platform support and tool antibodies for developing vaccines against RSV and other respiratory viruses.