The greater the energy contribution of the residues means that its mutations are more likely to affect the effectiveness of antibodies. As indicated in Figure , R246 takes the most vital part in five systems viz. 5-24 (PDB ID: 7L2F), 4A8 (PDB ID: 7C2L), FC05 (PDB ID: 7CWS), 2-51 (PDB ID: 7L2C), 1-87 (PDB ID: 7L2D) (Figure , Table ). In the five systems, the energy contribution of R246 is over 9.90 kcal/mol (Table ). Therefore, the mutations of R246 have the highest risk of immune escape.