Technical Abstract: A fundamental challenge of research on transgenic livestock is regulation of temporal and spatial transgene expression. Previously, a transgenic animal was produced that expressed lysostaphin, an anti-microbial protein, in the mammary gland during lactation. However, many bacterial infections of the mammary gland occur prior to parturition or during the involution period. Lactoferrin (LTF) expression is induced during these time periods in the mammary gland, and the LTF promoter would provide an ideal transcriptional regulatory element to drive lysostaphin transgene expression. To this end, the CHORI-240 bacterial artificial chromosome library was screened by hybridization with a cDNA probe corresponding to LTF. The DNA from the clone, E0014N19, was purified to isolate the LTF containing sub-fragment. The portion of LTF encompassing the 5' flanking region, exons 1 and 2, and intron 1 were sequenced. This segment of DNA is being used in reporter plasmids to test induction of gene expression during bacterial infection. GenBank Accession Number: AY319306.