Gene expression profiling and putative biomarkers of calves 3 months after infection with Mycobacterium avium subspecies paratuberculosis.
Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease (JD), a chronic granulomatous intestinal inflammation of ruminants. Current diagnostic tools lack sensitivity to detect JD early in infection; therefore, alternatives are desired. The objective was to identify potential biomarkers in whole blood of high- and low-dose (LD) MAP-challenged Holstein-Friesian calves 3 months after inoculation. Infected calves were designated MAP-positive using the IFN-γ release assay. Differential expression of transcripts in whole blood was compared between non-infected controls and HD, as well as LD calves, using the Affymetrix(®) GeneChip(®) Bovine Genome Array. Microarray data were analyzed using RMA and PLIER algorithms; 296 transcripts were differentially expressed (17 had ≥ 1.5 fold change). The HD and LD calves had differential gene expression profiles for up to 80% of differentially expressed genes. Pathway analyses using Ingenuity Pathway Analysis (IPA(®)) indicated inhibition of several defence mechanisms, including apoptosis, leukocyte and lymphocyte trafficking, overall repression of gene expression and potentially hydrogen peroxide production in macrophages. Further validation using qPCR verified increased expression of CD46, ICOS, and CEP350, but decreased expression of CTLA4, YARS, and PARVB in infected calves. Additionally, a comparison of seropositive and seronegative infected calves identified transcripts predictive of seroconversion. We concluded that IL6ST/gp130 and CD22 may have important roles in the induction of antibodies against MAP. Putative biomarkers of early MAP infection with roles in immune responses were identified; in addition, the importance of infective dose on biomarkers was determined.
Department of Production Animal Health, University of Calgary, 3330 Hospital Drive, Calgary, Alberta, Canada T2N 4N1. Electronic address: davij@ucalgary.ca.
Joel
J
David
Department of Production Animal Health, University of Calgary, 3330 Hospital Drive, Calgary, Alberta, Canada T2N 4N1; Department of Medicine, University of Calgary, Calgary, Alberta, Canada. Electronic address: barkema@ucalgary.ca.
Herman W
HW
Barkema
Department of Production Animal Health, University of Calgary, 3330 Hospital Drive, Calgary, Alberta, Canada T2N 4N1. Electronic address: rarmorti@ucalgary.ca.
Rienske
R
Mortier
Department of Production Animal Health, University of Calgary, 3330 Hospital Drive, Calgary, Alberta, Canada T2N 4N1; Department of Medicine, University of Calgary, Calgary, Alberta, Canada. Electronic address: subrata.ghosh@albertahealthservices.ca.
Subrata
S
Ghosh
Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5. Electronic address: lguan@ualberta.ca.
Le Luo
le L
Guan
Department of Production Animal Health, University of Calgary, 3330 Hospital Drive, Calgary, Alberta, Canada T2N 4N1. Electronic address: jdebuck@ucalgary.ca.
Jeroen
J
De Buck
D000818:Animals; D015415:Biomarkers; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism* / Q000382:microbiology; D008297:Male; D016927:Mycobacterium avium subsp. paratuberculosis; D010283:Paratuberculosis / Q000378:metabolism*; D025341:Principal Component Analysis; D059467:Transcriptome
D015415:Biomarkers
Biomarkers; Cattle; Johne's disease; Mycobacterium avium subspecies paratuberculosis; Transcriptomics