Abstract
The translation products of the human coronavirus (HCV) 229E open reading frames 1a and 1b, the polyproteins 1a and 1ab, are processed by virus-encoded proteinases. One of the key enzymes in this process is a chymotrypsin-like enzyme, the 3C-like proteinase. In this study we have identified an ORF 1b-encoded, 41 kDa processing product in HCV 229E- infected cells by using a monoclonal antibody with defined specificity. We show that this polypeptide is released from polyprotein 1ab by 3C- like proteinase-mediated cleavage of the peptide bonds Gln-6110/Gly- 6111 and Gln-6458/Ser-6459. Also, we have investigated the subcellular localization of the 41 kDa processing product. Immunofluorescence microscopy revealed a punctate, perinuclear distribution of the 41 kDa polypeptide in infected cells and an identical subcellular localization was observed for three additional pp1ab-derived polypeptides. In contrast, the virus nucleocapsid protein showed a homogeneous cytoplasmic localization.