Experimental infection of calves with bovine viral diarrhea virus strains isolated from haemorragic syndromes

Acute bovine viral diarrhea virus (BVDV) infection associated with thromboc ytopenia and hemorrhages is observed with increased frequency in Europe and North America. Experimental reproduction of hemorrhagic syndromes has been previously performed by others with American strains. The purpose of this study was to test BVDV strains isolated from sporadic cases of hemorrhagic syndrome, in Belgium and France. Six viral isolates were grown on cell cult ures and culture supernatants were inoculated to young BVDV-free calves, Vi ral isolation tests, blood parameters analysis and clinical signs recording were performed every other day, for 25 days after inoculation, For all BVDV strains, calves seroconverted but clinical signs of disease we re almost absent, This unexpected result could indicate a lower virulence o f strains tested in this study as compared to American hemorrhagic strains of BVDV.