Genetic identification of pestivirus strain Frijters as a border disease virus from pigs.

A pig pestivirus isolate, the Frijters strain, was characterized by using reverse transcription-PCR (RT-PCR), followed by RFLP and direct sequencing of the amplicons. Restriction endonuclease enzyme AvaI and Bg/I digestion of 5' NC genomic region PCR products suggested that Frijters strain belongs to the border disease viruses (BDV). This finding was confirmed by nucleotide sequencing of the amplified part of the 5-NC genomic region, which revealed 94% and 95% nucleotide similarity between the Frijters strain and the BDV prototype strains Moredun cp and Moredun ncp, respectively. On the other hand, 55-77% nucleotide identity was observed between the Frijters strain and prototypes of BVDV and CSFV. The amino acid similarity in the Npro (p20) region was 89% between Frijters and the Moredun strains and 70-77% between Frijters and the BVDV of CSFV strains. It was concluded that the Frijters virus is a member of the BDV group of the Pestivirus genus. Considering that this virus circulates in the large swine populations of Europe, the spread of certain pestiviruses to more than one animal species should not be considered sporadic. Since the presence of BDV in swine herds might be a confusing factor during classical swine fever eradication programmes, highly specific methods are required for reliable identification of these isolates. RT-PCR, followed by RFLP and sequencing of the amplicons proved to be a reliable approach for the rapid detection and identification of pestiviruses.