Abstract: The instant specification provides novel assays and systems for determining off-target effects of base editors. These assays and systems may comprise bacterial and/or eukaryotic cell systems and may be used to determine off-target editing frequencies, including Cas9-independent off-target editing frequencies. Also provided herein are novel base editors, wherein the base editors have reduced Cas9-independent off-target editing frequencies while maintaining high on-target editing efficiencies. Further provided are methods of contacting a nucleic acid molecule with these base editors to obtain reduced off-target editing frequencies, and in particular reduced Cas9-independent off-target editing events. Further provided are methods of treatment comprising administering these base editors to a subject. Also provided are pharmaceutical compositions comprising the base editors described herein, and nucleic acids, vectors, cells, and kits useful for the generation of these base editors.

Abstract: The present invention provides nanoparticles and compositions of various constructs that combine meta-stable viral proteins (e.g., RSV F protein) and self-assembling molecules (e.g., ferritin, HSPs) such that the pre-fusion conformational state of these key viral proteins is preserved (and locked) along with the protein self-assembling into a polyhedral shape, thereby creating nanoparticles that are effective vaccine agents. The invention also provides nanoparticles comprising a viral fusion protein, or fragment or variant thereof, and a self-assembling molecule, and immunogenic and vaccine compositions including the same.