Table 1.

Coefficients of antigenic similarity (R) between the three vaccines and JS-14-12-Ch.

Strains	R Value c	345–353 Residues of HN
NDV/AI4	0.35 a, 0.35 b	PDKQDYQIR
O/AI4	0.7 a, 1 b	PDKQDYQIR
LaSota	0.06 a, 0.12 b	PDEQDYQIR

^a Chicken embryo cross-neutralization test; ^b Cross-hemagglutination inhibition test; ^c 0.67 ≤ R ≤ 1.5, indicates no significant antigenic difference between the two viruses; 0.5 ≤ R ≤ 0.67 indicates a minor difference between the two viruses. R < 0.5 indicates a major difference between the two virus strains.