Epidemiology and genetic characterization of Border Disease Virus circulating in Sardinia

Border Disease Virus (BDV), a pestivirus from the Flaviviridae family, is an important pathogen of sheep and goats responsible for significant losses in farms around the world. In spite of the relevance of this pathogen there are only a few epidemiological studies on BDV infection and, as a consequence, the economic impact on small ruminant productions is probably under-estimated. The aims of this study are i) to determine the distribution of BDV in small ruminant farms in Sardinia and genetically characterize circulating strains ii) analyze the relation between seroprevalence, Somatic Cells Count (SCC) an milk yeld. ELISA was performed using “BVDV/MD/BDV p80 Protein Antibody Test Kit” (IDEXX) on serum of bulk tank milk (BTM) samples collected from Sardinian sheep flocks and goat herds between spring 2014 and 2015. The number of sampled farms corresponded to 8.5% of all registered farms in Sardinia. RNA was isolated using Qiamp Viral RNA mini kit from the cellular fraction of each ELISA positive BTV sample and amplified by rt-PCR using complementary primers to a highly conserved region in the untranslated regions (UTRs) of the viral genome. The amplicons were sequenced for phylogenetic analysis. Geographic distribution of collected specimen, seroprevalence and virological positive samples were analyzed via GIS (ESRI ARCGIS 10.3). ELISA screening shows a seroprevalence of 8.3% among goat farms and 10.5% among ovine farms. Ten from the ELISA positive samples were found rt-PCR positive. The sequence analysis indicates that all the amplified samples match with BDV genomes and the phylogenetic analysis revealed that all the viruses clustered in the same group classified as BDV-7. BDV-7 is the only group isolated in Sardinia so far.