Bovine Viral Diarrhoea Virus (BVDV) is responsible worldwide for severe economic losses on cattle farms. BVDV is
an RNA virus with a high genome variability having practical consequences on epidemiology, diagnosis and disease
control. Genetic monitoring was suggested as the first step in BVDV control. Thirty-seven Bovine Viral Diarrhoea
Viruses were identified in persistently infected cattle,mucosal disease-affected animals and in bulkmilk, and were characterised
genetically. The 5’UTR region was amplified and sequenced, and a phylogenetic analysis was carried out
comparing all the Italian sequences of BVDV available from the Genbank database. An unusual number of persistent
infected animals was evidenced onmore than one farm. Phylogenetic analysis attributed all our viruses to BVDV type
I and distinguished four different subgroups inside this genotype. Analysis of old and new viruses revealed the circulation
of viruses classified in subgroups BVDV Ia and Ij never reported in Italy.
