The Transgenic Cyt5CC7 T Cell Receptor mice were made by Dr. Barbara Fazekis de St. Groth and colleagues in 1992 at Stanford University using B10B6F1 donor embryos. The founder line I was transferred to the NIAID in 1992 and backcrossed for multiple generations to the B10.A congenic strain. The line was transferred to the NIAID Repository at Taconic in 1995 and embryo transfer derived. In 1996, the B10.A/Ai-Tg(Tcra5CC7,Tcrb5CC7)Iwep mice were intercrossed with homozygote Rag2 knockout mice on a congenic B10.D2 background (received at Taconic into the NIAID Repository in 1995 by ET derivation). The resulting F1 pups were mated to the B10.A/Ai-Tg(Tcra5CC7,Tcrb5CC7)Iwep once more and B10.A homozygotes were selected by typing with anti-H-2K antibodies. They were then intracrossed and Rag2 homozygotes identified by an absence of B220+ B cells. Mice homozygous for the transgene were then selected in further matings which included test crosses to wild type mice to identify Valpha11 homozygotes. These mice have bred true for the transgenic T cell receptor (TCR), Rag2-/-, Kk since June 1997. In multiple functional experiments the mice also have expressed the Ek restriction element (i.e. I-Ek MHC molecule). Finally recent examination of the T1 polymorphism in the TL region by SSCP analysis has shown this locus to also be derived from the B10.A allele.