Compositions and methods for identifying antigens which elicit an immune response

A method of identifying an isolated polynucleotide encoding an antigen capable of activating cytotoxic T cells, said method comprising:

• generating an expression vector, wherein said vector comprises a polynucleotide comprising a promoter/regulatory sequence, a polynucleotide encoding a signal sequence, a test polynucleotide, a polynucleotide encoding a cell receptor binding domain, and a polynucleotide comprising a polyadenylation signal, wherein each of said polynucleotides are operably linked to each other so as to effect major histocompatability class I or class II bound cell surface expression of a polypeptide encoded by said test polynucleotide on a cell into which said expression vector is introduced;
• introducing said expression vector into a cell to produce a transduced antigen presenting cell;
• and
• assessing whether any T cells in a population of naive T cells is activated upon contact of said population with said transduced antigen presenting cell, wherein activation of any of said T cells is an indication that said test polynucleotide is an isolated polynucleotide which encodes an antigen capable of activating cytotoxic T cells.