Characterization of the nonstructural and spike proteins of the human respiratory coronavirus OC43: comparison with bovine enteric coronavirus.
The nucleotide sequence of the region between the spike (S) and the membrane (M) protein genes, and sequences of the S and ns2 genes of the OC43 strain of human coronavirus (HCV-OC43) were determined. The ns2 gene comprises an open reading frame (ORF) encoding a putative nonstructural (ns) protein of 279 amino acids with a predicted molecular mass of 32-kDa. The S gene comprises an ORF encoding a protein of 1353 amino acid residues, with a predicted molecular weight of 149,918. Sequence comparison between HCV-OC43 and the antigenically related bovine coronavirus (BCV) revealed more sequence divergence in the putative bulbous part of the S protein (S1) than in the stem region (S2). The cysteine residues near the transmembrane domain and the internal predicted protease cleavage site are conserved in the HCV-OC43 S protein. Nucleotide sequence analysis of the region between the S and M gene loci revealed the presence of an unexpected intragenomic partial leader sequence and two ORFs encoding potential proteins of 12.9 and 9.5-kDa. These two proteins were identified as nonstructural by comparison with the homologous BCV genes. In vitro translation analyses demonstrated that the HCV-OC43 9.5-kDa protein, like its BCV counterpart, is poorly translated when situated down-stream of the 12.9-kDa ORF, but is expressed in infected cells, as shown by immunofluorescence. Interestingly, two ORFs, potentially encoding 4.9 and 4.8-kDa ns proteins in BCV are absent in HCV-OC43, indicating that they are not essential for viral replication in HRT-18 cells.
Mounir
S
S
Centre de Recherche en Virologie, Institut Armand-Frappier, Université du Québec, Laval, Canada.
Labonté
P
P
Talbot
P J
PJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D017934:Coronavirus / Q000235:genetics*; D028962:Coronavirus OC43, Human; D017938:Coronavirus, Bovine / Q000235:genetics*; D005814:Genes, Viral; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012367:RNA, Viral / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012004:Rectal Neoplasms; D013045:Species Specificity; D064370:Spike Glycoprotein, Coronavirus; D014407:Tumor Cells, Cultured; D014759:Viral Envelope Proteins / Q000235:genetics*; D017361:Viral Nonstructural Proteins / Q000096:biosynthesis / Q000235:genetics*; D015678:Viral Structural Proteins / Q000235:genetics*
D008562:Membrane Glycoproteins; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D017361:Viral Nonstructural Proteins; D015678:Viral Structural Proteins; C087633:nonstructural protein, coronavirus; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus