The B6.SJL Congenic model was developed by Boyse et al in 1975 by intercrossing C57BL/6Boy mice to SJL/J mice. Taconic received stock from the NIAID in 1995. The mice were derived by embryo transfer into the NIAID Transgenic Mouse Repository. The mice were backcrossed by Boyse to a C57BL/6Boy inbred background to select for SJL antigen type (now referred to as Ptprca or Ly5.1). Refreshed in 2007 from NIAID stock. Further backcrossed to the C57BL/6NTac background to NE8.