IDENTIFICATION OF HERD-SPECIFIC BOVINE VIRAL DIARRHEA VIRUS ISOLATES FROM INFECTED CATTLE AND SHEEP

Thirteen pestiviruses isolated from ruminants on four different farms in Sweden were compared antigenically and genetically. On two farms, v iruses were isolated from both cattle and sheep, a third farm containe d only sheep and a fourth only cattle. Seven viruses were isolated fro m six different cattle and six viruses were isolated from five differe nt sheep. Epitope conservation between the viruses was studied with a panel of 32 monoclonal antibodies, revealing that all of the isolates were BVDV-like. However, certain epitopes present in isolates from cat tle were lost following virus transmission to sheep. In vitro amplific ation of the 5'-untranslated region of the 13 isolates by the polymera se chain reaction (PCR) and subsequent analyses of amplified products with restriction enzymes also indicated that all 13 isolates belong to the BVDV group of pestiviruses. A fragment of the E2 (gp53) gene of e ach virus was amplified by PCR and a comparison of the amplified seque nce of 188 nucleotides separated the isolates into four groups each of which could be identified with a particular farm of origin. The 13 is olates were thus herd-specific rather than species-specific demonstrat ing that BVDV is readily transmitted between cattle and sheep.