 The study assessed the generation of protective immune responses in mice previously infected with respiratory syncytial virus, RSV, using virus-like particle, VLP, vaccine candidates containing a stabilized pre-fusion form of the RSVF protein or a stabilized post-fusion F protein. The results suggest that prior RSV infection can induce neutralizing antibody memory responses, which can be activated by pre-F protein VLPs but not by post-F protein VLPs or a subsequent infection. Additionally, the study found that the F protein confirmation has a major impact on enhancing production of neutralizing antibodies in RSV experienced animals and that the pre-F VLP stimulated significantly higher titers of total anti-G protein IgG than the post-F in both naive and RSV experienced animals. This article was authored by Laurie M. Cullen, Madeline R. Schmidt, and Trudy G. Morrison.