Fig. 1.

Positions of primers used to amplify fragments covering the whole spike (S) protein of turkey coronavirus (TCoV) isolate 540. The S protein of TCoV has 1203 amino acids and contains an N-terminal subunit (S1) and a C-terminal subunit (S2). The predicted cleavage site is located at amino acid 535. The amino acid (aa) position presented in the figure is from the start codon on the S protein gene of TCoV isolate 540 (GenBank accession number EU022525). The numbers above the names of the forward and reverse primers represent the position of the first or the last amino acid in the expressed S fragments