• Background: The Opg gene, also known as tumor necrosis factor receptor superfamily, member 11b (osteoprotegerin), encodes a secreted protein, osteoprogegerin,  and is a key gene regulating bone metabolism by blocking the RANKL-RANK signaling cascade.
• Targeting strategy: The exons 1-5 of mouse Opg gene that encode the full protein were knocked out in B-Opg KO mice.
• Validation: Mouse OPG was detectable only in wild-type C57BL/6JNifdc mice, but not in homozygous B-Opg KO mice.
• Application: This mouse is a spontaneous osteoporosis model for drug efficacy testing.

Gene targeting strategy for B-Opg KO mice. The exons 1-5 of mouse Opg gene that encode the full protein were knocked out in B-Opg KO mice.

Mouse-specific OPG expression analysis in homozygous B-Opg KO mice by ELISA. Serum were collected from wild-type mice C57BL/6JNifdc mice (+/+) (female, 16-week-old) and homozygous B-Opg KO mice (-/-) (female, 16-week-old), then analyzed by ELISA with mouse-specific Tnfrsf11b ELISA kit (Mouse Osteoprotegerin/TNFRSF11B Immunoassay: R&D, MOP00). Mouse OPG was exclusively detectable in C57BL/6JNifdc mice but not in homozygous B-Opg KO mice.