Immunogenicity of L1 capsomere derivatives. A) ELISA of L1 VLPs using antisera from mice immunized with L1 VLPs, or the capsomere derivatives 3-1, C-1 and 423-3. Horizontal axis represents serial two-fold dilutions starting at 1:5,000 and vertical axis represents OD405 nm of the resulting reactions. B) Immunoblot of purified RSV F protein using antisera from mice immunized with 3-1, C-1, or 423-3 (labelled on top of corresponding immunoblot lanes). Equal amounts of RSV F protein (approximately 0.5 μg/lane) were resolved on 10%/5% SDS-PAGE gels, transferred onto nitrocellulose, and detected with various mouse antisera (1:1,000 dilution) followed by goat anti-mouse IgG-HRP conjugate (1:10,000 dilution) and chemiluminescence. The sizes of the molecular weight standards are shown to the left of each marker ladder.