Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2022
Publication Date: 7/21/2022
Citation: Casas, E., Falkenberg, S.M., Dassanayake, R.P., Register, K.B., Neill, J.D. 2022. MicroRNA profiles for different tissues from calves challenged with Mycoplasma bovis or challenged with Mycoplasma bovis and bovine viral diarrhea virus. PLoS ONE. 17(7): Article e0271581. https://doi.org/10.1371/journal.pone.0271581.
Interpretive Summary: MicroRNAs (miRNAs) are small RNA molecules that are produced and circulate in cattle. They are known to regulate and modify gene expression in the animal, including genes from the immune system. The objective of this study was to establish if the expression of miRNAs was similar in five different tissues known to be related with the immune system, as well as in serum and blood (circulating), when challenged with Mycoplasma bovis or challenged with Mycoplasma bovis (M. bovis) and bovine viral diarrhes virus (BVDV). Calves were allotted in three groups: Control group (no challenge), Group challenged with M. bovis, and group challenged with M. bovis and BVDV. MiRNAs with the most differences in expression were observed in tissues from the immune system. Most tissues had a particular pattern of expression of miRNAs. MiRNAs in serum and blood seem unlikely candidates to establish what is happening in tissues of organs from the immune system; therefore, the use of circulating miRNAs from serum or blood to establish infection or disease will be of little use, unless a different approach is developed.
Technical Abstract: The objective was to determine differences in microRNAs counts (miRNAs) in several tissues of calves challenged with Mycoplasma bovis, (M. bovis) or with M. bovis and bovine viral diarrhea virus (BVDV). Eight calves approximately 2 months of age were randomly assigned to three groups: Control (CT; n equals 2), M. bovis (MB; n equals 3), and Coinfection (CO; n equals 3). On day 0, calves in CO were intranasally challenged with BVDV and calves in MB with M. bovis. On day 6, CO calves were challenged with M. bovis. Calves were euthanized 17 days post-challenge and serum (SER), white blood cells (WBC), liver (LIV), mesenteric (MLN) and tracheal-bronchial (TBLN) lymph nodes, spleen (SPL), and thymus (THY), were collected at necropsy. MiRNAs were extracted from each tissue from each calf. The correlation of miRNAs among MLN, TBLN, SPL, and THY, was high (r greater than 0.65), whereas the correlation from these tissues with SER, WBC, and LIV was low or non-existent (r less than 0.5). Significant (P less than 0.01) differences in miRNAs expression were observed in SER, LIV, TBLN, SPL, and THY. There were no significant (P greater than 0.05) miRNAs in WBC. In SER, the CO group had levels of miR-1343-3p significantly higher than the CT and MB groups (P equals 0.0071). In LIV and SPL, the CO group had the lowest counts for all miRNAs with statistically significant differences among groups. In TBLN, the CT group had the highest counts of miRNAs, compared to MB and CO, in 14 of the 21 significant miRNAs. In THY, the CO group had the highest counts, in 4 of the 6 significant miRNAs. Circulating miRNAs to assess disease condition or to develop intervention strategies to minimize respiratory diseases in cattle caused by BVDV or M. bovis will be of little use, unless an alternative approach is developed to use them as indicators of disease.