Genetically modified major histocompatibility complex mice

A method of making a genetically modified mouse, comprising

• (A) replacing at an endogenous mouse classical MHC I locus a nucleic acid sequence encoding α1, α2, and α3 domains of an endogenous mouse classical MHC I polypeptide with a nucleic acid sequence encoding α1, α2, and α3 domains of a human classical MHC I polypeptide to form a first nucleotide sequence that encodes a chimeric human/mouse MHC I polypeptide,
• wherein the first nucleotide sequence comprises from 5′ to 3′:
• a nucleic acid sequence encoding α1, α2, and α3 domains of a human classical MHC I polypeptide operably linked to an endogenous nucleic acid sequence encoding transmembrane and cytoplasmic domains of the endogenous mouse classical MHC I polypeptide, and
• wherein the first nucleotide sequence is operably linked to an endogenous mouse MHC I regulatory element and an MHC class I leader encoding sequence, and
• (B) modifying an endogenous mouse β2 microglobulin locus by:
• (a) replacing at the endogenous mouse β2 microglobulin locus a nucleic acid comprising sequences set forth in exon 2, exon 3, and exon 4 of an endogenous mouse β2 microglobulin gene with a nucleic acid comprising sequences set forth in exon 2, exon 3, and exon 4 of a human β2 microglobulin gene to form a second nucleotide sequence that encodes a functional humanized β2 microglobulin polypeptide, wherein the second nucleotide sequence comprises from 5′ to 3′:
• a nucleic acid comprising a sequence set forth in exon 1 of the endogenous mouse β2 microglobulin gene operably linked to a nucleic acid comprising sequences set forth in exon 2, exon 3, and exon 4 of the human β2 microglobulin gene,
• wherein the second nucleotide sequence is operably linked to an endogenous mouse β2 microglobulin regulatory element, or
• (b) introducing at the endogenous mouse β2 microglobulin locus a nucleic acid comprising a human β2 microglobulin gene to form a third nucleotide sequence that encodes a functional human β2 microglobulin polypeptide, wherein the third nucleotide sequence comprises from 5′ to 3′:
• a nucleic acid comprising sequences set forth in exon 1, exon 2, exon 3, and exon 4 of a human β2 microglobulin gene,
• wherein the third nucleotide sequence is operably linked to an endogenous mouse β2 microglobulin regulatory element, and
• wherein the mouse expresses, on the surface of nucleated cells, the chimeric human/mouse MEW I polypeptide non-covalently associated with the functional humanized or human β2 microglobulin polypeptide.