Molecular characterization of the S protein gene of human coronavirus OC43

The gene encoding the spike protein of the OC43 strain of human coronavirus (HCV-OC43) was cloned and sequenced. The complete nucleotide sequence revealed an open reading frame of 4062 nucleotides encoding a protein of 1353 amino acids with a predicted M r of 150078. Structural features include 22 N-glycosylation sites, an N-terminal hydrophobic signal sequence of 17 amino acids, an hydrophilic cysteine-rich sequence of 35 amino acids near the C terminus, and a potential proteolytic cleavage site (RRSR) between amino acid residues 758 and 759, yielding S1 and $2 segments of 84730 and 65 366 M r, respectively. The predicted amino acid sequence of the spike protein of HCV-OC43 has 91 % identity with that of the Mebus strain of bovine coronavirus, revealing more sequence divergence in the putative bulbous part (S1) than in the predicted stem region ($2). Human coronaviruses (HCV) are enveloped positive-stranded RNA viruses that cause respiratory infections and have been associated with gastrointestinal n