Pestivirus bovine viral diarrhea virus polypeptides: identification of new precursor proteins and alternative cleavage pathways.

The genome of pestivirus bovine viral diarrhea virus (BVDV) contains a single 11,964 nt long open reading frame (ORF) that is capable of encoding a 449 kDa putative polyprotein. Although previous studies have described many virus-coded polypeptides that are believed to arise by post- and/or co-translational proteolytic processing in infected cells, there are two separate regions in the ORF for which no polypeptide products could be identified. In the present study using site specific antisera, we identified two new large proteins of Mr 175 and 172 kDa which encompass two previously described smaller precursor proteins, p125 and p133, respectively. These two large precursor proteins together with two other previously described proteins p22 and gp118 (Mr approx. 84 kDa; unglycosylated) account for the predicted Mr of the putative 449 kDa polyprotein precursor. Furthermore, we discovered three additional polypeptides of Mr 168, 96 and 72 kDa encoded by the last third of the genome. These proteins may arise by an alternative cleavage pathway of the precursor protein p172. A modified and updated map of BVDV ORF incorporating the above findings is presented.