Gene targeting strategy for B-NDG hTFR1 mice plus. The exons 4-19 of mouse Tfr1 gene that encode extracellular domain are replaced by human counterparts in B-NDG hTFR1 mice plus. The genomic region of mouse Tfr1 gene that encodes cytoplasmic portion is retained. The promoter, 5’UTR and 3’UTR regions of the mouse gene are also retained. The chimeric TFR1 expression is driven by endogenous mouse Tfr1 promoter, while mouse Tfr1 gene transcription and translation will be disrupted.

Strain specific TFR1 expression analysis in heterozygous B-NDG hTFR1 mice plus by flow cytometry. Bone marrow was collected from wild-type B-NDG mice (+/+) and heterozygous B-NDG hTFR1 mice plus (H/+). Protein expression was analyzed with anti-mouse TFR1 antibody (Biolegend, 113808) and anti-human TFR1 antibody (Biolegend, 334108) by flow cytometry. Mouse TFR1 was detectable in wild-type B-NDG mice and heterozygous B-NDG hTFR1 mice plus. Human TFR1 was exclusively detectable in heterozygous B-NDG hTFR1 mice plus.