Expression vectors encoding epitopes of target-associated antigens and methods for their design
The invention disclosed herein is directed to methods of identifying a polypeptide suitable for epitope liberation including, for example, the steps of identifying an epitope of interest; providing a substrate polypeptide sequence including the epitope, wherein the substrate polypeptide permits processing by a proteasome; contacting the substrate polypeptide with a composition including the proteasome, under conditions that support processing of the substrate polypeptide by the proteasome; and assaying for liberation of the epitope. The invention further relates to vectors including a housekeeping epitope expression cassette. The housekeeping epitope(s) can be derived from a target-associated antigen, and the housekeeping epitope can be liberatable, that is capable of liberation, from a translation product of the cassette by immunoproteasome processing. The invention also relates to a method of activating a T cell comprising contacting a substrate polypeptide with an APC and contacting the APC with a T cell.
1. A vector comprising a housekeeping epitope expression cassette, wherein the housekeeping epitope is derived from a target-associated antigen, wherein the housekeeping epitope is liberatable from a translation product of the cassette by immunoproteasome processing, wherein the antigen is NY-ESO-1, wherein the housekeeping epitope is NY-ESO-1 157-165 (SEQ ID NO:12), and wherein the vector comprises a nucleic acid sequence encoding SEQ ID NO:18.
2. A vector comprising a housekeeping epitope expression cassette, wherein the housekeeping epitope is derived from a target-associated antigen, wherein the housekeeping epitope is liberatable from a translation product of the cassette by immunoproteasome processing, wherein the antigen is NY-ESO-1, wherein the housekeeping epitope is NY-ESO-1 157-165 (SEQ ID NO:12), and wherein the vector comprises a nucleic acid sequence encoding SEQ ID NO:22.
3. The vector of claim 2 , comprising a nucleic acid sequence encoding SEQ ID NO:20.
4. A vector comprising a housekeeping epitope expression cassette, wherein the housekeeping epitope is derived from a target-associated antigen, wherein the housekeeping epitope is liberatable from a translation product of the cassette by immunoproteasome processing, wherein the antigen is NY-ESO-1, wherein the housekeeping epitope is NY-ESO-1 157-165 (SEQ ID NO:12), and wherein the vector comprises a nucleic acid sequence encoding the polypeptide sequence M-(B-A-D-D-A-B-A-A), and wherein M is an initiator Methionine, B is the sequence of SEQ ID NO:12, A is the sequence of SEQ ID NO:13, and D is the sequence of SEQ ID NO:15 (SEQ ID NO:1582).