Strain specific IFNB1 expression analysis in homozygous B-hIFNB1 mice by ELISA. Serum were collected from wild type (+/+) and homozygous B-hIFNB1 mice (H/H) stimulated with LPS for 2 hours in vivo, and analyzed by ELISA with species-specific IFNB1 ELISA kit. Mouse IFNB1 was detectable in wild type mice. Human IFNB1 was exclusively detectable in homozygous B-hIFNB1 mice but not in wild type mice.