Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2019
Publication Date: N/A
Technical Abstract: T cells are an important component of the adaptive immune response and play a critical role in memory response. The thymus is the primary site for maturation of T cells, but is susceptible to pathogen-associated depletion. The objective of this study was to determine differences in microRNA (miRNA) expression in thymus of calves challenged with bovine viral diarrhea virus (BVDV), Mycoplasma bovis, or both pathogens. BVDV is known to cause reduction of the thymus. Calves approximately 2 months of age were randomly assigned to one of four groups: Coinfection (CO; n=3), bovine viral diarrhea virus (BV; n= 3), Mycoplasma bovis (MB; n=3), and Control (CT; n=2). Day zero, calves in groups CO and BV were intranasally challenged with BVDV and group MB with Mycoplasma bovis. Day 6, CO calves were challenged with Mycoplasma bovis. Calves were euthanized 17 days post challenge and appropriate tissues were collected at necropsy. MiRNAs were extracted from thymus and sequenced on the Illumina 3000 Hi-Seq sequencer. A total of 262,698,223 sequences were identified as miRNAs. MiRNAs analyzed had a total of at least 1,000 copies for all animals. No differences were observed between CT and MB groups in miRNA expression. Calves in CO had greater expression of miR-200b (P= 0.0017), miR-9-5p (P = 0.0044), and miR-147 (P = 0.003), and had the lowest expression of miR-2285p (P = 0.0045), when compared to the calves in BV, MB, CT. Calves in CO and BV had greater expression of miR-141 (P = 0.0074), miR-29c (P = 0.0086), and miR-22-5p (P = 0.0051), and had lower expression of miR-154b (P = 0.0037), when compared to calves in CT and MB. MiR-147 and miR-141 are highly expressed in bovine alveolar macrophages. MiR-2285p and miR-154b were down-regulated in CO, but there is no associated reference. These miRNAs could potentially be targets for pathogens in the thymus during colonization and production of respiratory disease.