GENETIC-HETEROGENEITY WITHIN THE CODING REGIONS OF E2 AND NS3 IN STRAINS OF BOVINE VIRAL DIARRHEA VIRUS

We have amplified and sequenced parts of the genomes of eleven laboratory strains of bovine viral diarrhea (BVD) virus originating from North America, New Zealand and Europe. The cumulative nucleotide (nt) sequence heterogeneity of the amplified fragments located in the analysed region of the gene encoding the nonstructural protein NS3 (P80) was 24% as compared to 47% for E2 (Gp53), The nt substitutions in the E2 region resulted in replacements in 42% of amino acid (aa) positions, while the deduced aa sequence of all BVD virus strains remained identical in NS3 and differed from the corresponding region of classical swine fever viruses. This makes possible the differentiation of bovine and porcine pestiviruses. It is suggested that genetic heterogeneity results from passage in transiently infected animals.