Monoclonal antibody based in vitro potency assay as a predictor of antigenic integrity and in vivo immunogenicity of a Respiratory Syncytial Virus post-fusion F-protein based vaccine.

•The basis of immunogenicity of Respiratory Syncytial Virus (RSV) Fusion (F) protein (RSVsF) based vaccine is addressed.•An in vitro relative potency (IVRP) assay is a sensitive indicator of RSVsF antigen integrity.•IVRP is a conservative predictor of in vivo immunogenicity elicited by RSVsF.•Site A epitope of RSVsF showed greater stability against stress conditions than site C.•These results have potential impact on development of recombinant protein based vaccines.