Hybridization analysis of genomic variability among isolates of bovine viral diarrhoea virus using cDNA probes

Genomic variability among 28 cytopathic and 37 non-cytopathic isolates of BVDV was evaluated using hybridization analysis. Total RNA, isolated from cell cultures infected with BVDV, was probed with each of three plasmids containing cDNA derived from the cytopathic BVDV-NADL isolate. The three cDNA plasmid probes represented about 40% of the BVDV-NADL genome. The probes originated from the 5' end of the viral genome, the region of the genome coding for the p80 polypeptide and the 3' end of the genome. Three temperatures, 63 degrees C, 53 degrees C and 43 degrees C, were used for hybridization and washing and allowed approximately 29%, 36%, and 43% mismatch, respectively. Fifteen of the BVD viral isolates differed by less than 29% from BVDV-NADL in all three of the regions probed. Seventeen of the BVD viral isolates differed between 36% and 43% from BVDV-NADL in all three of the regions probed. Ten viral isolates differed by more than 43% from BVDV-NADL in all the regions probed. The remaining viral isolates exhibited different levels of similarity to BVDV-NADL in the three areas probed.