Gene expression analysis of IL- 2 in milk somatic cell from normal and E.coli mastitis of Holstein dairy heifers

Mastitis is the most costly disease in dairy cattle and usually occurs in response to intramammary bacterial infections. The identification of genes that their expression are altered in response to bacterial infections and to classify them into biologically functional groups help to understanding of the host response to a specific pathogen. Therefore, the aims of this study were to investigate the expression of IL-2 gene in the mammary gland of healthy Holstein heifers at three stages of early, mid and late lactation and E.coli mastitis heifers. For this purpose, total RNA extracted from milk somatic cell of 18 healthy Holstein heifers (6 animals for each stage of lactation) and 4 clinical E.coli mastitis heifers in first lactation. To study of gene expression, the expression of IL-2 gene was compared with GADPH gene as a reference gene. For gene expression analysis, the REST, V2.0.13 2009 software was used. Our results showed significant increase of IL-2 expression in E.coli mastitis in comparison of different lactation stages. Maximum and minimum differences were found with early and late stages of lactation, respectively. Our study indicates that it was possible to verify changes in the expression of IL-2 gene in normal and E.coli mastitis heifers and the IL-2 gene may play important role in fighting intramammary infection caused by E.coli.