Genomic and Virulence Investigations of a Novel Porcine Deltacoronavirus Strain Identified in South Korea

Figure 7

Schematic diagram of genetic variations in the S gene between KNU-1607 and GNU-2105. The top illustration represents the organization of the S protein, featuring S1 and S2 subunits that contain an N-terminal domain (S1-NTD), a C-terminal domain (S1-CTD), an N-terminal central helix (CH-N), a C-terminal central helix (CH-C), a fusion peptide (FP), an N-terminal heptad repeat (HR-N), and a C-terminal heptad repeat (HR-C). Red- and blue-highlighted areas in the diagram depict sialic acid-binding (S1-NTD, residues 52–277) and receptor binding (S1-CTD, residues 300–419) domains of PDCoV. Lightly shaded areas (GNU-2105) are identical to KNU-1607 (thick horizontal black line), and the vertical black bars represent one amino acid sequence that is divergent from that of KNU-1607. Red and blue boxes indicate the S1-NTD and S1-CTD regions, respectively. The digits in parentheses on the right indicate the number of amino acid changes and the percent identity compared with KNU-1607. The amino acid sequence alignments of the partial S1-NTD (red line, residues 85–247) and S1-CTD (blue line, residues 300–400) between KNU-1607 and GNU-2105 are presented at the bottom. Two amino acid changes (V326I and T337S) in the S1-CTD are highlighted in yellow.