CELLULAR PLATFORM FOR RAPID AND COMPREHENSIVE T-CELL IMMUNOMONITORING

1 .- 82 . (canceled)

83 . A suspension-adapted, peptide-presenting cell genetically modified with a heterologous nucleic acid comprising a nucleotide sequence encoding a heterologous polypeptide comprising, in order from N-terminus to C-terminus:

a) a peptide having a length of from 5 to 20 amino acids;

b) a first linker;

c) a β-2 microglobulin polypeptide;

d) a second linker;

e) a major histocompatibility complex (MHC) heavy chain;

f) a third linker;

g) a fluorescent protein or an immunoglobulin Fc polypeptide;

h) a fourth linker; and

i) a mammalian transmembrane domain.

84 . The cell of claim 83 , wherein the heterologous polypeptide comprises an immunoglobulin Fc polypeptide.

85 . The cell of claim 83 , wherein the heterologous polypeptide comprises a fluorescent protein.

86 . The cell of claim 83 , wherein the transmembrane domain is an MHC heavy chain transmembrane domain.

87 . The cell of claim 83 , wherein the nucleotide sequence comprises a viral packaging signal 3′ of the nucleotide sequence encoding the transmembrane domain.

88 . A plurality of the peptide-presenting cell of claim 83 , wherein the plurality comprises at least two different encoded 5 to 20 amino acid peptides presented on the surface of the cell, or the membrane-bound portion of the cell.

89 . The plurality of cells of claim 88 , wherein the plurality comprises at least 100 different peptides having a length of from 5 to 20 amino acids.

90 . A virus or virus-like particle comprising a heterologous polypeptide comprising, in order from N-terminus to C-terminus:

a) a peptide having a length of from 5 to 20 amino acids;

b) a first linker;

c) a β-2 microglobulin polypeptide;

d) a second linker;

e) a major histocompatibility complex (MHC) heavy chain;

f) a third linker;

g) a fluorescent protein or an immunoglobulin Fc polypeptide;

h) a fourth linker; and

i) a mammalian transmembrane domain,

wherein the peptide having a length of from 5 to 20 amino acids is displayed on the surface of the virus or the virus-like particle.

91 . The virus or virus-like particle of claim 90 , wherein the virus is a lentivirus or a retrovirus.

92 . A plurality of the virus or virus-like particle of claim 90 .

93 . The plurality of claim 92 , wherein the plurality comprises at least 2 different peptides having a length of from 5 to 20 amino acids.

94 . The plurality of claim 92 , wherein the plurality comprises at least 100 different peptides having a length of from 5 to 20 amino acids.

95 . A method of identifying a T-cell epitope, the method comprising:

a) contacting a T-cell with the plurality of cells of claim 88 , under conditions that permit the T-cell to bind to one of the peptides having a length of from 5 to 20 amino acids, forming a complex between the T-cell and the peptide-presenting cell;

b) recovering the complex; and

c) sequencing the nucleic acid encoding the peptide having a length of from 5 to 20 amino acids present in the peptide-presenting cell present in the complex, thereby identifying the T-cell epitope.

96 . The method of claim 95 , wherein the plurality of cells are mammalian cells.

97 . The method of claim 95 , wherein the T-cell is a peripheral T-cell obtained from a subject.

98 . The method of claim 95 , wherein the complex is recovered by flow cytometry.

99 . A method of identifying a T-cell epitope, the method comprising:

a) contacting a T-cell with the plurality of virus or virus-like particle of claim 92 , under conditions that permit the T-cell to bind to one of the peptides having a length of from 5 to 20 amino acids, forming a complex between the T-cell and the virus or virus-like particle;

b) recovering the complex; and

c) sequencing the nucleic acid encoding the peptide having a length of from 5 to 20 amino acids present in the peptide-presenting cell present in the complex, thereby identifying the T-cell epitope.

100 . The method of claim 99 , wherein the virus is a lentivirus or a retrovirus.

101 . The method of claim 99 , wherein the T-cell is a peripheral T-cell obtained from a subject.

102 . The method of claim 99 , wherein the complex is recovered using a secondary antibody directed to an epitope in the virus or virus-like particle.

103 . The method of claim 99 , wherein the plurality of viruses or virus-like particles comprises at least 10 3 different peptides having a length of from 5 to 20 amino acids.