Title: Computational analysis of bovine milk exosomal miRNAs profiles derived from uninfected and Streptococcus uberis infected mammary gland Authors
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2014
Publication Date: April 23, 2014
Citation: Aswath, K., Jiajie, S., Schroeder, S.G., Reinhardt, T.A., Lippolis, J.D., Sonstegard, T.S. 2014. Computational analysis of bovine milk exosomal miRNAs profiles derived from uninfected and Streptococcus uberis infected mammary gland. BARC Poster Day, Poster 62, pp. 74. Technical Abstract: The dairy cattle industry in the U.S. contributes an estimated 7 billion dollars to the agribusiness economy. Bacterial infections that cause disease like mastitis, affect health of the lactating mammary gland, and negatively impacts milk production and milk quality, costing producers an estimated 2 billion dollars in annual costs. Little genetic improvement has been made relative to selection for increased resistance to bacterial infection of the mammry gland, and development of new phenotypes are necessary to better dissect the genetic components of host immune response to infection. As such, previous studies to detect microRNAs in the blood of human cancer patients have shown the potential of using short non-coding (~23nt) miRNAs as biomarkers for disease identification, based on the specific expression of microRNA only associated with diseased patients. The goal of this study was to investigate the types of miRNA transcripts present in bovine milk. Specifically, exosomes isolated from milk may contain specific miRNAs indicative of bacterial infection of the mammary gland. For this study, exosome samples were collected from the milk of 5 uninfected cows as well as milk 2-days post-infection with Streptococcus uberis. Total RNA was extracted from exosomes and small RNA libraries were constructed for next generation sequencing. Over 44 million sequencing reads were produced from 6 libraries and analyzed by genome alignment to identify 328 different expressed miRNAs. The top 10 most prevalent miRNAs in both control and infected replicates accounted for approximately 80% of all aligned reads, with the remaining differentially expressed miRNAs showing much lower expression. A total of 15 miRNAs transcript types were found to be differentially present in exosomes during infection (p<0.05), and these small RNA transcripts will serve as target molecules to develop potential diagnostic tests that can be used to detect early stages of bacterial infection of the mammary gland. Such information can then be used to generate phenotypic data in diary resource populations to investigate genome methods for genetic improvement to incidence of mastitis.