Expression of biologically active human clotting factor IX (hF IX) in the mammary gland of transgenic mice

The DNA of human factor IX (hF IX) gene vector pMC IX m, which had been proven to be able to express in in vitro and living cells, was introduced into 586 zygotes of Kunming White Mice by positive pressure microinjection technique with manual operation. The 499 survival embryos after microinjection were then transferred into pseudopregnant recipient mice and 216 F-0 pups were born. The analysis of PCR and Southern blot hybridization showed that, of the 216, 6 (2 females and 4 males) were integrated with foreign DNA in their genomes, giving an integration frequency of 3% (6/216). Two F-0 female transgenic mice could express hF IX protein in their milk and the content was over 100 ng/mL as measured with ELISA. The biological activities of hF IX in the milk of two F-0 mice were 44.67% and 79.43%, respectively.