Submitted to: BioMed Central (BMC) Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2018
Publication Date: 3/13/2018
Citation: Casas, E., Cai, G., Kuehn, L.A., Register, K.B., McDaneld, T.G., Neill, J.D. 2018. Association of circulating transfer RNA fragments with antibody response to Mycoplasma bovis in beef cattle. BioMed Central (BMC) Veterinary Research. 14:89. https://doi.org/10.1186/s12917-018-1418-z.
Interpretive Summary: Molecules circulating in live cattle, known as Transfer RNA fragments (tRFs), have been suggested to be regulators of gene expression in mammals. In the present study, we established differences in type and quantity of tRFs between animals that were positive or negative to being exposed to a bacterium that causes respiratory disease (Mycoplasma bovis). Establishing the difference in type and quantity of tRFs between healthy and diseased cattle will produce information needed to understand how genes in the animal are turned on or off, and how the animal’s immune system responds to diseases. This report is the initial phase in identifying tRFs as potential candidates for use as a diagnostic indicator of chronic exposure, or whether intervention strategies could be developed as an alternative to antibiotics for controlling disease due to this bacterium.
Technical Abstract: The objective of this study was to identify transfer RNA fragments associated with a serum antibody response to Mycoplasma bovis in beef cattle. Serum from sixteen beef calves was collected at three points: summer after calves were born, fall at weaning, and the following spring. All sera collected in summer were ELISA negative for IgG reactive with M. bovis. By the fall, eight animals were seropositive (positive group), while eight remained negative (negative group). By spring, all animals in both groups were seropositive. The small non-coding RNA fractions were extracted from sera and sequenced on the Illumina HiSeq next-generation sequencer. Based on prototypical features of transfer RNAs, a total of 261,502,003 sequences were identified as 5’ transfer RNA fragments (tRF5), and were further characterized. The tRF5s encoding alanine, glutamic acid, glycine, lysine, proline, selenocysteine, threonine, and valine were associated (P< 0.05) with antibody response against M. bovis. tRF5s encoding alanine, glutamine, glutamic acid, glycine, histidine, lysine, proline, selenocysteine, threonine, and valine were associated (P< 0.05) with season. There were interactions (P< 0.05) between antibody response to M. bovis and season for tRF5 encoding selenocysteine (anticodon UGA), proline (anticodon CGG), and glutamine (anticodon TTG). Selenocysteine is a rarely used amino acid that is incorporated into proteins by the opal stop codon (UGA), and its function is not well understood. Production of tRF5s may be associated with a host defense mechanism triggered by bacterial infection, or it may provide some advantage to a pathogen during infection of a host. Further studies are needed to establish if tRF5s could be used as a diagnostic indicator of chronic exposure, or whether intervention strategies could be developed as an alternative to antibiotics for controlling disease due to M. bovis.