BACKGROUND: Cathelicidins comprise a major group of host-defence peptides. Conserved across a wide range of
species, they have several functions related to host defence. Only one cathelicidin has been found in humans but
several cathelicidin genes occur in the bovine genome. We propose that these molecules may have a protective
role against mastitis. The aim of this study was to characterise the cathelicidin gene-cluster in the bovine genome
and to identify sites of expression in the bovine mammary gland.
RESULTS: Bioinformatic analysis of the bovine genome (BosTau7) revealed seven protein-coding cathelicidin genes,
CATHL1-7, including two identical copies of CATHL4, as well as three additional putative cathelicidin genes, all
clustered on the long arm of chromosome 22. Six of the seven protein-coding genes were expressed in leukocytes
extracted from milk of high somatic cell count (SCC) cows. CATHL5 was expressed across several sites in the
mammary gland, but did not increase in response to Staphylococcus aureus infection.
CONCLUSIONS: Here, we characterise the bovine cathelicidin gene cluster and reconcile inconsistencies in the
datasets of previous studies. Constitutive cathelicidin expression in the mammary gland suggests a possible role for
these host defence peptides its protection.