Expression and characterization of part of hog cholera virus non-structural proteins

In a preceding paper, the molecular cloning and partial nucleotide sequence of the Alfort strain of hog cholera virus (HCV) was described. To study the genetic organization of the 3'-end of the HCV genome, which encodes some of the non-structural proteins, a cDNA fragment (S2.20) of 849 nucleotides was subcloned into the bacterial expression vector pGEX-3X and expressed in Escherichia coli as a S2.20-glutathione-S-transferase fusion protein (S2.20-GST). This protein was used to produce HCV-specific monoclonal antibodies. Using Western immunoblotting, these antibodies could be used to identify a specific gene product of the HCV Alfort strain. Three proteins, with relative molecular weights of 76, 107 and 145 kDa, were detected. These proteins were also observed for eight other HCV strains. With the bovine viral diarrhoea virus (BVDV) NADL strain and the border disease virus (BDV) Aveyron strain, only one protein, with a relative molecular weight of 72 kDa, was detected. With the BVDV New York strain, two proteins, with relative molecular weights of 70 and 100 kDa, were recognized. The significance of these findings with respect to pestivirus genomic organization is discussed.