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Open Access Research article

Characterisation and expression profile of the bovine cathelicidin gene repertoire in mammary tissue

Cormac J Whelehan1, Anne Barry-Reidy1, Kieran G Meade2, P David Eckersall3, Aspinas Chapwanya4, Fernando Narciandi1, Andrew T Lloyd5 and Cliona O’Farrelly1*

Author Affiliations

1 Comparative Immunology Group, Trinity Biomedical Sciences Institute, Trinity College Dublin, Pearse Street, Dublin 2, Ireland

2 Animal & Bioscience Research Department, Teagasc, Grange, Co Meath, Ireland

3 Division of Animal Production and Public Health, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Rd, Glasgow G611QH, UK

4 Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, South Africa

5 Current address: Department of Science and Health, Carlow Institute of Technology, Kilkenny Road, Carlow, Ireland

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BMC Genomics 2014, 15:128  doi:10.1186/1471-2164-15-128

Published: 13 February 2014

Abstract

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.

Keywords:
Cathelicidin; Hidden Markov Model (HMM); Gene cluster; Locus; Tissue expression