Selection of BVDV genotype II isolates using a monoclonal antibody and FACS-analysis

The infection of cattle with the bovine viral diarrhea virus (BVDV) in Germany is gaining attention and guidelines for the "protection of cattle farms against BVDV infections" were passed in 1997. New investigations about the damages induced by BVDV infections as well as the new occurrence of so-called BVDV genotypes (BVDV I and II) made the problems to become aware. The newly described BVDV genotype considerably differs both genetically and antigenetically from the up to now known BVD-viruses (BVDV I). The subdivision in BVDV genotypes I and II is based on genomic differences, which are determined by sequence analyses of different parts of the viral genome. Here, we describe the classification of BVDV in genotypes using a monoclonal antibody and indirect immunofluorescence with flow cytometry (FACS) based analysis. The suitability of the mab WB160 (Central Veterinary Laboratory, Weybridge; UK) for the classification of both BVDV-genotypes was first checked using genetically defined BVDV isolates. While all BVDV I isolates (n = 20) reacted with high fluorescence signals, the mab WB160 could not detect any of the defined BVDV II isolates (n = 20). Subsequently, 505 BVDV field strains isolated between 1993-1997 were screened for both genotypes using the mab WB160 and FAGS analysis. 33 (6,5 %) of the BVDV isolates were classified as BVDV II.