Expression of recombinant human lysozyme in the milk of transgenic mice

Human lysozyme is a 130-aa (amino acid) alka-line polypeptide, and has both anti-bacterial and anti-viral properties which make it an important component of human natural immunity system. As a first step toward the ultimate goal of improving the anti-bacterial properties of bovine and ovine milk, a transgenic mouse that contains the genomicDNA sequence of the human lysozme gene has been gener-ated for the first time. From 83 mice generated by microin-jection, a total of 6 positive transgenic mice were identified by PCR and Southern blot. F1 mice positive for transgene inlines were also detected by PCR. This shows that transgene could be transmitted from founder transgenic mice to their offspring. Recombinant human lysozyme (rHlys) was found in the whey of 3 female positive transgenic mice by Western blot. The highest concentration of rHlys for transgenic mice was 0.2 mg/mL. The antibacterial activity of the whey fortransgenic mice was highly enhanced up to 0.4 times as much as that of human, while that of non-transgenic mouse wasvery low. Although the lysozyme activity of transgenic mice is still lower than that of human, the rHlys exhibits the same specific activity as that of human lysozyme. It provides astrong basis for further studies into the possible application of rHlys express in mammary gland.