Recombinant RSV antigens, nucleic acid molecules encoding the antigens, and vaccine compositions comprising the same

An antigen comprising a recombinant respiratory syncytial virus (RSV) F protein, wherein the recombinant RSV F protein comprises an antigenic region flanked with an N-terminal heptad repeat (HRN) region and a C-terminal heptad repeat (HRC) region, and wherein

• the HRN region and the HRC region comprise amino acid sequences of SEQ ID NO:
• 1 and SEQ ID NO:
• 2, respectively;
• the antigenic region comprises two or more antigenic sites selected from the group consisting of site Ø, site II, and site IV including amino acid sequences of SEQ ID NO:
• 3, SEQ ID NO:
• 4, and SEQ ID NO:
• 5, respectively;
• and
• the antigenic sites are linked to each other by a linker independently consisting of 2 to 20 amino acids.