C57BL/6 mice deficient in K^b were generated by homologous recombination in the laboratory of Dr. Francois Lemonnier of The Institut Pasteur, Paris France.

Generation of H-2 K^b Targeted Mutation mice-The K^b gene was disrupted by replacing the 2nd and 3rd exons with an HPRT minigene inserted in the opposite transcriptional orientation. The disrupted gene was introduced into an E14TGa(H-2b and b2ma) HPRT deficient embryonic stem cell of 129/OLA origin. After injection into B6 blastocysts, the resultant germline chimeras were backcrossed twice to C57BL/6Ji mice and offspring heterozygous for the H2-K^b knockout allele were crossed to generate H2-K^b deficient mice (K^b -/-). Inactivation of the H2-K^bgene was confirmed by Southern blot analysis on tail DNA and by FACS analysis. The targeted mutation mice were subsequently backcrossed to C56BL/6Ji mice another 10 times before being intercrossed to achieve homozygosity . Six pairs of the N12 homozygous mice were transferred from Dr. Lemonnier to the NIAID repository at Taconic in 2001 where they were embryo transfer derived.