Abstract
The replicase open reading frame lb (ORF1b) protein of equine arteritis virus (EAV) is expressed from the viral genome as an ORF1ab fusion protein (345 kDa) by ribosomal frameshifting. Processing of the ORF1b polyprotein was predicted to be mediated by the nsp4 serine protease, the main EAV protease. Several putative cleavage sites for this protease were detected in the ORF1b polyprotein. On the basis of this tentative processing scheme, peptides were selected to raise rabbit antisera that were used to study the processing of the EAV replicase ORF1b polyprotein (158 kDa). In immunoprecipitation and immunoblotting experiments, processing products of 80, 50, 26, and 12 kDa were detected. Of these, the 80-kDa and the 50-kDa proteins contain the putative viral polymerase and helicase domains, respectively. Together, the four cleavage products probably cover the entire ORF1b-encoded region of the EAV replicase, thereby representing the first complete processing scheme of a coronaviruslike ORF1b polyprotein. Pulse-chase analysis revealed that processing of the ORF1b polyprotein is slow and that several large precursor proteins containing both ORF1a- and ORF1b-encoded regions are generated. The localization of ORF1b-specific proteins in the infected cell was studied by immunofluorescence. A perinuclear staining was observed, which suggests association with a membranous compartment.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
