• OX40, also known as CD134 and TNFRSF4, is a 50 kD type I transmembrane glycoprotein.
• OX40 is a member of the TNF receptor family. OX40 is expressed on activated T lymphocytes including Th1, Th2, Th17, and Treg cells. The interaction of OX40 with OX40L results in B cell proliferation and antibody secretion, regulation of primary T cell expansion, and T cell survival. 
• The exons 1-5 of mouse Ox40 gene that encode extracellular domain are replaced by human counterparts in B-hOX40 mice(C). The genomic region of mouse Ox40 gene that encodes signal peptide, transmembrane domain and cytoplasmic portion are retained. The promoter, 5’UTR and 3’UTR region of the mouse gene are also retained. The OX40 expression is driven by endogenous mouse Ox40 promoter, while mouse Ox40 gene transcription and translation will be disrupted. 
• Mouse OX40 protein was only detectable in wild-type BALB/cCrSlcNifdc mice, and human OX40 protein was only detectable in homozygous B-hOX40 mice(C).
• Application: This product is used for pharmacodynamics and safety evaluation of  drugs.

Gene targeting strategy for B-hOX40 mice(C). 

The exons 1-5 of mouse Ox40 gene that encode extracellular domain are replaced by human counterparts in B-hOX40 mice(C). The genomic region of mouse Ox40 gene that encodes signal peptide, transmembrane domain and cytoplasmic portion are retained. The promoter, 5’UTR and 3’UTR region of the mouse gene are also retained. The OX40 expression is driven by endogenous mouse Ox40 promoter, while mouse Ox40 gene transcription and translation will be disrupted. 

Strain specific analysis of OX40 mRNA expression in wild-type BALB/cCrSlcNifdc mice and homozygous B-hOX40 mice(C) by RT-PCR. Spleen RNA were isolated from wild-type BALB/cCrSlcNifdc mice (+/+) and homozygous B-hOX40 mice(C) (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human OX40 primers. Mouse OX40 mRNA was only detectable in wild-type mice. Human OX40 mRNA was exclusively detectable in homozygous B-hOX40 mice(C) but not in wild-type mice. 

Strain specific OX40 expression analysis in homozygous B-hOX40 mice(C) by flow cytometry. Splenocytes were collected from wild-type BALB/cCrSlcNifdc mice (+/+) and homozygous B-hOX40 mice(C) (H/H) stimulated with anti-CD3ε in vivo, and protein expression was analyzed with anti-mouse OX40 antibody (Biolegend, 119414)  and anti-human OX40 antibody (Biolegend, 350004) by flow cytometry. Mouse OX40 was only detectable in T cells of wild-type BALB/cCrSlcNifdc mice. Human OX40 was only detectable in T cells of homozygous B-hOX40 mice(C), but not in wild-type BALB/cCrSlcNifdc mice.