The IL-1β knockout was developed by Zheng et al. in the laboratory of Lex Van der Ploeg at Merck Research Laboratories. AB 2.1 (129S7/SvEvBrd) embryonic stem cells, gene targeted by positive-negative selection, were injected into C57BL/6 blastocysts. The resultant chimeras were backcrossed for three generations to the MHC congenic B10.RIII-H2r to transfer the H2r haplotype to the targeted mutant. The IL-1ß heterozygotes were intercrossed to achieve homozygosity. This model was distributed as Taconic line 612, which is no longer available. The line was subsequently backcrossed by a third party to C57BL/6J and the H2r haplotype was removed. This current version of the model was imported to Taconic in 2018 and is congenic on C57BL/6J (NE7) with some residual genomic DNA from the 129 ES cells according to SNP testing.
Zheng, H.; Fletcher, D.; Kozak, W.; Jiang, M.; Hofmann, K. J.; Corn, C. A.; Soszynski, D.; Grabiec, C.; Trumbauer, M. E.; Shaw, A.; Kostura, M. J.; Stevens, K.; Rosen, H.; North, R. J.; Chen, H. Y.; Tocci, M. J.; Kluger, M. J.; Ploeg, L. H. V. D. Immunity 1995, 3 (1), 9–19.