Genetic diversity of international bovine viral diarrhoea virus (BVDV) isolates: identification of a new BVDV-1 genetic group.

In the last decade, several studies were performed to characterise bovine viral diarrhoea virus (BVDV) isolates and define genetic groups by genotyping. Much data is now available from GenBank, predominantly sequences from the 5' untranslated region (5'-UTR). In order to find out whether genetic grouping of isolates from different countries could be harmonised, 22 new isolates from five countries were analysed in combination with published sequences. Eighteen of these isolates were typed as BVDV genotype 1 (BVDV-1), and one isolate from Argentina and three isolates from Brazil were typed as BVDV-2. BVDV-1 isolates were clustered into five previously defined genetic groups: BVDV-1a, b, d, e and f. Two isolates from Finland and one from Egypt formed a group which was tentatively labelled as BVDV-1j, since statistical support was low. By using a fragment of the Npro gene for typing, we found that these isolates fall into the same group as a deer strain, and are statistically significant. Some Swiss BVDV strains taken from GenBank were found in a new genetic group which was designated as BVDV-1k. The BVDV-2 isolates included in this study seemed to fall into two genetic groups.

Genetic diversity of recent bovine viral diarrhoea viruses from the southeast of Austria (Styria).

To characterise the bovine virus diarrhoea virus (BVDV) isolates circulating in the southeastern region of Austria, namely in the province of Styria, 71 blood samples collected between 1998 and 2000 from persistently infected cattle in 62 herds were subjected to genetic typing. For this, 288bp fragments from the 5' untranslated region (5'-UTR) were amplified by polymerase chain reaction after reverse transcription (RT-PCR). The products were sequenced and used for phylogenetic analysis. Seventy virus isolates were typed as BVDV species 1 (BVDV-1). Only one isolate was typed as BVDV species 2 (BVDV-2), representing the first isolate of this pestivirus genotype found in Austria. In addition, phylogenetic analysis revealed that viruses belonging to five genetic groups within BVDV-1 are circulating in Styria. Most viruses (53) were found in group BVDV-1f, nine viruses in BVDV-1h, four viruses in BVDV-1b, three viruses in BVDV-1d and one virus in BVDV-1g. No virus was found in genetic group BVDV-1a, which is dominant in the UK and widely distributed in USA. Likewise, the BVDV isolates predominating in a neighbouring country, namely Germany, belonged to different genogroups than those circulating in Styria. We conclude that in a particular region and environment certain BVDV-1 genetic groups predominate. New groups, including BVDV-2, can be introduced, e.g. by trade of animals. The low incidence of BVDV-2 in Styria is in concert with the sporadic occurrence of these viruses in other regions of Europe.