The HLA-B7 model was generated by Pharmexa-Epimmune. The model was created by microinjecting a chimeric transgene combining a fragment of the cDNA clone of the human HLA-B*0702 gene that included leader sequence, α1 and α2 domains ligated to a fragment of the murine H2-K^b gene containing the α3, transmembrane and cytoplasmic domains. Sequencing indicates that the model contains the CAG promoter rather than the H-2L^d promoter described in the literature. From a functional perspective, the CAG promoter is expected to drive strong, ubiquitous expression, which may mimic the expression pattern of human class I HLA proteins on the surface of most nucleated cells. This transgene was microinjected into CxB6 zygotes. The resultant mice from Founder Line B7.xx were on backcrossed four generations to C57BL/6J. They were then crossed onto murine B2m knockout/human B2m microinjected line from Chella David at Mayo. This crossbred line was backcrossed two additional generations to C57BL/6J and then bred to homozygosity for all three genes. Taconic received stock from Pharmexa-Epimmune in 2008. The line was embryo transfer derived. SNP testing showed that the line was not congenic, and so additional backcrosses were initiated. The line was then intracrossed to homozygosity for all three genes. In the production colony, wild type BALB/cAnNTac females are bred to triple homozygous males on the B6 background to produce CB6F1 pups.