Human nerve growth factor beta (hNGF‐β): mammary gland specific expression and production in transgenic rabbits

Transgenic rabbits carrying gene constructs encoding human nerve growth factor beta (hNGF‐β) cDNA were generated. Expression of hNGF‐β mRNA was restricted to the mammary gland of lactating rabbits. Western Blot analysis revealed a polypeptide of 13.2 kDa in the milk of transgenic animals. hNGF‐β was purified from the milk by a two‐step chromatographic procedure. Electrospray mass spectroscopy analysis of purified hNGF‐β depicted a molecular weight of 13 261 Da per subunit. The biological activity of the hNGF‐β was tested using PC12W2 cells and cultures of dorsal root ganglion neurons from chicken embryos. Crude defatted milk from transgenic animals and purified hNGF‐β demonstrated full biological activity when compared to commercial recombinant hNGF‐β.