Changes in miRNA in Response to Infection with Bovine Viral Diarrhoea Virus in Cattle

Bovine viral diarrhoea (BVD) is a widespread disease that causes significant economic loss for the cattle industry through reduced immune competence and loss of fertility. Bovine viral diarrhoea virus (BVDV), is a single strand, positive sense RNA virus belonging to the Flaviviridaefamily. CD4⁺T helper cells play an important role in the cellular mediated response in the early phases of infection, whereas dendritic cells and monocytes become infected and spread the virus through body. The current research investigated miRNAs expression following experimental infection with a live disabled BVDV to identify the connection between infection and immune response and to identify potential biomarkers of infection.

Three 10 month old BVDV negative Holstein cows were vaccinated with MUCOSIFFA^®(Merial), an attenuated live vaccine against a BVDV-2. Blood was taken at T0 then at 24h and 5 days after the vaccination. Buffy coat was prepared from blood, total RNA extracted and miRNA expression quantified using a human miRNA array (Exiqon mirNome). Data were analysed using the Exiqon “GenExqPCR”  software then normalised with Normfinder. One-way ANOVA was used to identify miRNA differentially expressed following the vaccination. Eight miRNA showed significantly affected levels. Putative pathways involving these miRNAs were identified using mirPath on the DIANA website. Six of the differentially expressed miRNA targeted genes of the MAPK pathway which regulates white peripheral cell proliferation and six miRNAs also targeted the chemokine signalling pathway.

This work was supported by the InnovaGen project of the Italian Ministry of Agriculture