The HLA-A1 model was generated by Pharmexa-Epimmune. The model was created by microinjecting a chimeric transgene combining a fragment of the genomic clone of the human HLA-A*0101 gene that included the leader sequence, α1 and α2 domains ligated to a fragment of the murine H2-K^b gene containing the α3, transmembrane and cytoplasmic domains, all under the control of the murine H2-K^b promoter. This transgene was microinjected into C57BL/6 zygotes. The resultant mice from Founder Line A1.01 were on an inbred C57BL/6 background. The line was maintained by breeding hemizygotes to wild type C57BL/6NTac mice for 10 generations. Taconic received stock from Pharmexa-Epimmune in 2008. The line was embryo transfer derived by breeding C57BL/6NTac wild type females to hemizygous males. The foundation and expansion colonies are maintained through continuous breeding of hemizygous males to wild type C57BL/6NTac females. The strain is considered fully congenic to C57BL/6NTac. In the production colony, wild type C57BL/6NTac animals are bred to hemizygous animals on the C57BL/6NTac background to produce hemizygous pups. In addition, another production colony is breeding BALB/cAnNTac females with hemizygous males on the C57BL/6NTac background to produce hemizygous CB6F1 pups, which are sold under model #9662.