Genotyping of bovine viral diarrhoea viruses isolated from cattle in northern Italy

Following the first official report of a clinically severe outbreak of bovi ne viral diarrhoea disease occurring in a farm in northern Italy, which had originated from the use of a live vaccine contaminated with a strain of BV D genotype II virus, a retrospective study on the prevalence of BVDV genoty pes in Italy became highly relevant. For this purpose, the genotype of 78 B VDV-positive specimens, obtained in 1998-1999 from dairy cattle in an area near to where the outbreak occurred, was characterized by PCR technology. T wo sets of primers, spanning the 5' UTR of BVDV genome, were used sequentia lly in a first round of RT-PCR, performed on viral RNA extracted directly f rom 15 clinical samples and 63 BVDV-infected cell-culture fluids; a second PCR assay followed to selectively amplify only BVDV genotype II. All the vi ruses under study were characterized as BVDV genotype I. As well as contrib uting to a better understanding of the prevalence of BVDV genotypes in the field, the results of the present study illustrate the possibility that nov el BVDV strains can emerge in susceptible animals through the use of contam inated immunobiological products for bovine use.