Construction of Vector of Gene Targeting to Multiple Loci for Leghorn Chicken Based on BAC with Cre/lox P System

The significance of the technique of gene-targeting vector to multiple loci is shown as follows. First, the targeting loci were increased to 100-300. Second, the problems of unstable expression of inserted genes were partially solved. Third, the need for safety against toxicity integration was resolved. Fourth, the forbidden zone of gene integrating on the repetitive DNA sequences was broken through.