Bovine beta-defensins: identification and characterization of novel bovine beta-defensin genes and their expression in mammary gland tissue.

beta-Defensin genes code for multifunctional peptides with a broad-range antimicrobial activity. In this project we hypothesized that beta-defensin genes may be candidate genes for resistance to mastitis. In this article we describe the identification and genomic characterization of eight bovine beta-defensin genes, including six novel defensin genes and two pseudogenes. Expression in the bovine mammary gland of one of the novel genes, DEFB401, has been demonstrated, as well as the expression of LAP, TAP, DEFB1, BNBD3, BNBD9, and BNBD12. For genomic characterization, 20 BACs from two different bovine BAC libraries (RZPD numbers 750 and 754) were isolated by PCR screening with beta-defensin consensus primers derived from published sequences. PCR products from BACs generated with consensus primers have been subcloned and sequenced, revealing a total of 16 genes and two pseudogenes. Six novel beta-defensin genes share the typical exon-intron structure and are highly homologous to published bovine beta-defensin genes. They are named DEFB401- DEFB405 and LAP-like, and two novel pseudogenes are named EBD-P and EBD-P2. Analysis of mammary gland tissue-derived cDNA from nine cows with different clinical findings demonstrated the expression of several beta-defensin genes mentioned above. First results indicate that the lactational status of the cow presumably has no influence on gene expression. Competent knowledge of antimicrobial activity of beta-defensins from literature, the abundance of beta-defensin mRNA in the bovine mammary gland, and the inducibility of some genes give first evidence that beta-defensins may play a role in local host defense during udder infections.