The OT-II microinjected model was developed by Dr. Francis Carbone of Monash Medical School and Dr. William R. Heath of the Walter and Eliza Hall Institute. The model was created by microinjecting the rearranged Valpha2 and Vbeta5 T cell receptor into B6 x B6.C-H2bm1 blastocysts. Taconic received stock from Keio University in June 2001, and the mice were rederived by backcrossing to C57BL/6NTac. OT-II transgenic mice were crossed with a homozygous C57BL/6NTac Rag2 targeted mutation model (RAGN12-M), and then intercrossed for homozygosity at the Rag2 allele. The model was rederived by embryo transfer and is maintained by mating of mice that are homozygous for Rag2 disruption and heterozygous for the OT-II transgene to mice that are homozygous for the Rag2 disruption and wild type for OT-II.
Due to poor production by ko/ko;tg/tg x ko/ko;tg/tg setups, Taconic will transition the colony to the following mating format: ko/ko;tg/wt (male or female) by ko/ko;wt/wt. During the transition period, inventory will include mice that are homozygous and hemizygous for the OT-II transgene. Eventually, only mice that are hemizygous for the OT-II transgene will be available. A review of flow cytometry analysis for hemizygous and homozygous OT-II mice showed that T cell numbers and TCR expression levels were similar for the two genotypes. We expect minimal to no functional difference between the genotypes in typical experiments.
Shinkai, Y, Rathbun, G, Lam, KP, Oltz, EM, Stewart, V, Mendelsohn, M, Charron, J, Datta, M, Young, F, Stall, AM, and Alt, FW. (1992) RAG-2-Deficient Mice Lack Mature Lymphocytes Owing to Inability to Initiate V(D)J Rearrangement, Cell, 68: 855-867.
Barnden MJ, Allison J, Heath WR, Carbone FR. (1998) Defective TCR expression in transgenic mice constructed using cDNA-based α- and Β-chain genes under the control of heterologous regulatory elements. Immunol Cell Biol 76:34-40.