Expression Analysis of a Bovine β-Casein/Human Lactoferrin Hybrid Gene in Transgenic Mice

Abstract

In our previous study, using a bovine β-casein/human lactoferrin hybrid gene, transgenic mice were generated to target the expression of human lactoferrin (hLF) into the mammary glands. Here, we report the fidelity of transgene expression by eleven transgenic mice and their progeny. Expression of hLF in lactating mice was demonstrated by northern and western blots, ELISA, and immunohistochemical staining. Northern blot analysis in five different tissues revealed that the transgene was expressed in the mammary gland. hLF was expressed in five of eight transgenic mouse lines analyzed by ELISA. The expression level of hLF in milk at day 10 of lactation ranged from 2.5 to 200 μg/ml. The apparent molecular weight of the recombinant hLF was indistinguishable from the native form upon immunoblotting. Immunohistochemical staining revealed that hLF in transgenic mice was exclusively expressed in the epithelial cells of mammary gland. The transgenic mice produced in this study provide a model for the eventual generation of transgenic farm animals producing high levels of hLF in their milk.