Drs. Ji-Liang Gao and Philip Murphy in the Laboratory of Molecular Immunology, NIAID, made the FPR-/- mouse by targeted gene disruption in 1999. The Fpr1 gene was mutated by replacing a 150 bp DNA fragment in the Fpr1 open reading frame with a neomycin resistance gene. The disrupted Fpr1 gene was introduced to 129/Sv ES cells to create chimeric mice, and then the chimeric founders were backcrossed to C57BL/6NAi mice for 10 generations in the NIAID barrier facility at Taconic. At this point, it was discovered that the C57BL/6NAi line had become contaminated with the IFNγ knockout gene. Line 4169 was then backcrossed to C57BL/6NTac (Taconic B6) for 5 generations in order to eliminate the contaminating gene and put the strain onto the Taconic C57BL/6 subline background.
Gao J-L, Lee E, and Murphy PM. (1999) Impaired anti-bacterial host defense in mice lacking the N-formylpeptide receptor. J. Exp. Med., 189: 657-662.