Dynamic Expression Profile Of Ova-miR-34a-5p During Goatpox Virus Infection And Identification Of Its Target

microRNAs (miRNAs) are a subclass of small non-coding RNAs, involved in the regulation of expression of target genes at a post-transcriptional level. It is well documented that miRNAs play essential roles in diverse biological processes. Studies have shown that miRNAs are involved in the process of virus infection, and they can be used as effective targets for controlling diseases. So this study investigated a dynamic expression profile of ova-miR-34a-5p during goatpox virus infection and identified its target, in order to uncover the mechanisms of pathogenicity of pox viruses and lay the foundation for elucidating miRNA essential roles in sheeppox and during the infection process.In order to investigate the role of ova-miR-34a-5p during goatpox virus infection, qPCR primers specific for ova-miR-34a-5p were first screened out, its dynamic expression profile at the different infectious points was analyzed using qPCR and the potential target genes were predicted using TargetScam RNA22 and miRanda databases. Target genes were analyzed by use of Gene Onthology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Then the relationship between ova-miR-34a-5p and the predicted targets was further validated using double fluorescence reporting detection system. The results were as follows:(1) The results showed that the expression levels of ova-miR-34a-5p at 0.5h,4h and 10h post infection were not significantly altered compared to that at Oh (P> 0.05), whilst its level at 24h was significantly up-regulated (P< 0.05), following a decrease at 48h (P> 0.05), suggesting its association with viral DNA synthesis.(2) Among the putative targets of ova-miR-34a-5p, some were transcription factors including mycn, of which the functions are mainly related to protein binding, transcriptional regulation, cell proliferation and cell location.(3) The results of double fluorescence reporting detection system showed that fluorescence intensity was significantly down-regulated in the group co-transfected with mycn-WT (wild type) and ova-miR-34a-5p mimics compared to the control co-transfected with mycn-WT (wild type) and negative control (P< 0.01), whereas the group co-transfected with mycn-mut (mutant) and ova-miR-34a-5p mimics showed no changes compared to the control (P> 0.05), indicating the suppression of transcription factor mycn expression by ova-miR-34a-5p.Conclusion:The above results suggest that ova-miR-34a-5p is possibly involved in viral DNA sythesis by targeting mycn, but the mechanisms remain to be established yet.