Disclosed herein are peptides of 27 amino acid residues, and compositions comprising said peptides. Also disclosed herein are their uses in treating or preventing a viral infection.

Provided herein are cell surface receptors that include an extracellular binding domain, a transmembrane domain, an intracellular signaling domain, and a protease cleavage site disposed between the extracellular binding domain and the intracellular signaling domain. In certain aspects, the cell surface receptors are engineered cell surface receptors, such as chimeric antigen receptors (CARs). Also provided are cells that include such receptors (e.g., where the cells express the receptors on their surface) and pharmaceutical compositions including such cells. Nucleic acids that encode the cell surface receptors, cells including such nucleic acids, and pharmaceutical compositions including such cells, are also provided. Also provided are methods for regulating signaling of a cell surface receptor, and methods of using the cells of the present disclosure, including methods of using such cells to administer a regulatable cell-based therapy to an individual.

Provided herein are cell surface receptors that include an extracellular binding domain, a transmembrane domain, an intracellular signaling domain, and a protease cleavage site disposed between the extracellular binding domain and the intracellular signaling domain. In certain aspects, the cell surface receptors are engineered cell surface receptors, such as chimeric antigen receptors (CARs). Also provided are cells that include such receptors (e.g., where the cells express the receptors on their surface) and pharmaceutical compositions including such cells. Nucleic acids that encode the cell surface receptors, cells including such nucleic acids, and pharmaceutical compositions including such cells, are also provided. Also provided are methods for regulating signaling of a cell surface receptor, and methods of using the cells of the present disclosure, including methods of using such cells to administer a regulatable cell-based therapy to an individual.