Distribution pattern of bovine viral diarrhoea virus strains in intensive cattle herds in Italy
2001
Luzzago, C. | Bandi, C. | Bronzo, V. | Ruffo, G. | Zecconi, A.
The genetic variation of bovine viral diarrhoea virus (BVDV) was studied by comparative nucleotide sequence analysis of 26 Italian field strains collected during the period 1995-2000 in 18 cattle herds. A fragment within the 5'-untranslated region (UTR) was sequenced directly from gel-purified products obtained by reverse transcription polymerase chain reaction. BVDV-1b (n = 14), -1c (n = 1), -1d (n = 1) and BVDV-2 (n = 2) strains have been isolated. Most herds were infected by BVDV-1b. Pairwise similarity and cluster analysis of the remaining BVDV-1 isolates (n = 8) did not provide a clear-cut assignation to defined BVDV-1 groups. This is the first time that a BVDV-2 isolation was reported in Italy. Among BVDV-2 reference strains, Italian BVDV-2 isolates showed the highest sequence similarity with the CD87 strain. Both BVDV-2 strains were isolated in two healthy animals from different herds. The 5'-UTR sequence of one of the two BVDV-2 strains was identical to a German BVDV field strain. Complete nucleotide homology was found only among BVDV strains isolated from the same herd, showing a herd-specific clustering. Moreover, 99.6% homology was observed between strains from herds linked by livestock trade. Despite the small number of BVDV isolates analysed, it revealed a high level of genetic diversity among Italian field BVDV strains.
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