Submitted to: Frontiers in Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2017
Publication Date: N/A
Citation: N/A Interpretive Summary: Small pieces of RNA, called microRNAs, circulate in cattle and are known to regulate gene expression in mammals, such as immune responses to viral infections and disease. In this study, we identified microRNAs that had differences in number of copies between control animals and animals that had a viral infection caused by bovine viral diarrhea virus (BVDV). This virus is often associated with respiratory disease in cattle, and leads to financial stress on producers. Identifying microRNAs associated with BVDV infection in cattle will improve the current knowledge of microRNAs role in an immune response to a viral infection, and may provide possible markers for producers or veterinarians to use to identify a BVDV infection in a cattle herd.
Technical Abstract: Bovine viral diarrhea virus (BVDV) is an RNA virus that is often associated with respiratory disease in cattle. MicroRNAs have been proposed as indicators of exposure to respiratory pathogens. The objective of this study was to identify microRNAs in cattle that had been challenged with a non-cytopathic field strain of BVDV. Five colostrum deprived neonate Holstein calves were challenged with BVDV (challenged) and 4 were mock challenged (control). Serum from all calves was collected at 4 different times: prior to challenge (day 0) and at 4, 9, and 16 days post challenge. RNA was extracted from sera, and small non-coding RNAs were obtained using next-generation sequencing. A total of 905,861 sequences identified 427 microRNAs. Sixty-two microRNAs had > 1,000 total reads across all samples. Bta-miR-339a, bta-miR-185, bta-miR-486, Bta-miR-92a, bta-miR-30e-5p, bta-let-7c, and bta-miR-2284x were significantly different (P<0.05) across time regardless of challenge status. Bta-miR-423-5p (P=0.008) and bta-miR-151-3p (P=0.005) were significantly different between challenged and control animals across time. In challenged animals, bta-miR-423-5p peaked in number of reads by day 4 and steadily declined from day 4 to 16. In control animals, bta-miR-423-5p declined from day 0 to day 9 and increased in number by day 16. By day 16, both challenged and control animals had similar levels of bta-miR-423-5p, and these levels were similar to day 0 levels. Bta-miR-151-3p peaked at day 9 in challenged animals, while control animals decreased across time. By day 16, the number of reads of bta-miR-151-3p were similar between challenged and control animals. The level in challenged animals had returned to day 0 levels by day 16, whereas the levels for control animals was significantly lower (P=0.006) than day 0. Further studies are needed to establish if bta-miR-423-5p or bta-miR-151-3p could be used as a biomarker for exposure to BVDV.