title: The Identification of Circulating MiRNA in Bovine Serum and Their Potential as Novel Biomarkers of Early Mycobacterium avium subsp paratuberculosis Infection.
abstract: Mycobacterium avium subspecies paratuberculosis (MAP) is the aetiological agent of Johne's disease (JD), a chronic enteritis in ruminants that causes substantial economic loses to agriculture worldwide. Current diagnostic assays are hampered by low sensitivity and specificity that seriously complicate disease control; a new generation of diagnostic and prognostic assays are therefore urgently needed. Circulating microRNAs (miRNAs) have been shown to have significant potential as novel biomarkers for a range of human diseases, but their potential application in the veterinary sphere has been less well characterised. The aim of this study was therefore to apply RNA-sequencing approaches to serum from an experimental JD infection model as a route to identify novel diagnostic and prognostic miRNA biomarkers. Sera from experimental MAP-challenged calves (n = 6) and age-matched controls (n = 6) were used. We identified a subset of known miRNAs from bovine serum across all samples, with approximately 90 being at potentially functional abundance levels. The majority of known bovine miRNAs displayed multiple isomiRs that differed from the canonical sequences. Thirty novel miRNAs were identified after filtering and were found within sera from all animals tested. No significant differential miRNA expression was detected when comparing sera from MAP-challenged animals to their age-matched controls at six-month's post-infection. However, comparing sera from pre-infection bleeds to six-month's post-infection across all 12 animals did identify increased miR-205 (2-fold) and decreased miR-432 (2-fold) within both challenged and control groups, which suggests changes in circulating miRNA profiles due to ageing or development (P<0.00001). In conclusion our study has identified a range of novel miRNA in bovine serum, and shown the utility of small RNA sequencing approaches to explore the potential of miRNA as novel biomarkers for infectious disease in cattle.
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland.
authors.forename: Damien
authors.initials: D
authors.lastname: Farrell
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland.
authors.forename: Ronan G
authors.initials: RG
authors.lastname: Shaughnessy
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland.
authors.forename: Louise
authors.initials: L
authors.lastname: Britton
authors.affiliation: UCD School of Agriculture and Food Science, University College Dublin, Dublin, Ireland; UCD Conway Institute, University College Dublin, Dublin, Ireland.
authors.forename: David E
authors.initials: DE
authors.lastname: MacHugh
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland.
authors.forename: Bryan
authors.initials: B
authors.lastname: Markey
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland; UCD School of Medicine, University College Dublin, Dublin, Ireland; UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland; UCD Conway Institute, University College Dublin, Dublin, Ireland.
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Gordon
mesh_terms: D000818:Animals; D001483:Base Sequence; D015415:Biomarkers / Q000097:blood*; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D035683:MicroRNAs / Q000097:blood* / Q000235:genetics; D008969:Molecular Sequence Data; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D009690:Nucleic Acid Conformation; D010283:Paratuberculosis / Q000097:blood / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology
chemical_list: D015415:Biomarkers; D035683:MicroRNAs; D007371:Interferon-gamma