TAAR6 and infection: To identify the functional regions of O/Tibet/CHA/6/99tc and O/Fujian/CHA/9/99tc that are responsible for FMDV-HS interaction to establish an efficient infection in WT-CHO cells, the coding regions of VP0 (VP4 and VP2) and VP1 genes of O/Tibet/CHA/6/99tc (TAR6) and O/Fujian/CHA/9/99tc (FJ9) were substituted into plasmid pOFS to construct the chimeric full-length cDNA clones, pOFS/TAR6-VP0, pOFS/TAR6-VP1, pOFS/FJ9-VP0 and pOFS/FJ9-VP1, respectively (Figure 2).