The present invention is generally related to modified or mutated respiratory syncytial virus fusion (F) proteins and methods for making and using them, including immunogenic compositions such as vaccines for the treatment and/or prevention of RSV infection. In one aspect, the invention provides recombinant RSV F proteins comprising modified or mutated amino acid sequences as compared to wild-type RSV F proteins. In general, these modifications or mutations increase the expression, reduce the cellular toxicity, and/or enhance the immunogenic properties of the RSV F proteins as compared to wild-type RSV F proteins. In certain exemplary embodiments, the RSV F proteins are human RSV F proteins.
