New insights into processing of bovine viral diarrhea virus glycoproteins Erns and E 1

Received 8 April 2009 Accepted 19 June 2009 Bovine viral diarrhea virus (BVDV) is a member of the genus Pestivirus within the family Flaviviridae. Its single-stranded RNA encodes a polyprotein that is cleaved coand posttranslationally by viral and cellular proteases. However, the cleavage between the envelope proteins E and E1 is still unexplained. In this study, an E–E1 protein could be identified and characterized with a new E1-specific antiserum. With bicistronic constructs bearing a deletion in the E-encoding region and expressing E or the E–E1 protein, it could be shown that this protein is not essential for virus replication. Furthermore, two putative cleavage sites were mutated in eukaryotic expression plasmids, as well as in full-length cDNA constructs. The mutation of position P3 of a potential signal peptide peptidase site abolished cleavage completely and no infectious virus progeny could be observed, indicating that cleavage of the E–E1 protein is indispensable for virus growth.