Expression analysis of lung miRNAs responding to ovine VM virus infection by RNAseq

MicroRNAs (miRNAs) are short endogenous, single-stranded, non-coding small RNA molecules of about 22 nucleotides in length. They regulate gene expression post-transcriptionally by silencing mRNA molecules and they regulate many physiological processes. Visna-Maedi virus (VMV) is a lentivirus that causes Visna-Maedi disease (VM) in sheep characterised by pneumonia, mastitis, arthritis and encephalitis; and affects cells of the monocyte/macrophage lineage. So far, there are no studies in the role of miRNAs in this viral disease. Using RNAseq technology and bioinformatics analysis the expression of miRNAs in different phases of the disease were studied. A total of 212 miRNAs were found, of which 46 were conserved sequences found for the first time in sheep and 12 were completely novel. Differential expression analysis showed changes in several miRNAs comparing uninfected and seropositive groups, but did not detect significant differences between seropositive asymptomatic and diseased sheep. The high increase in expression of oar-miR-21 agrees with the increase of the same miRNA detected in other viral diseases. In addition, the target prediction of dysregulated miRNAs revealed that they control genes involved in proliferation-related signalling pathways like PI3K-Akt, AMPK and ErbB. MicroRNA expression by RNA-seq in three phases of infection with Visna-Maedi virus in sheep: Seronegative, seropositive asymptomatic and seropositive with clinical lessions. 5 replicates for each group.