TABLE 3.

Comparison of the binding of MAbs to pH-sensitive epitopes in the prefusion intermediate (pH 5 and 4°C) or the densensitized (pH 5 and 37°C) form of the HA of PR8 virus to the pH 7.5 form^a

MAbb	Binding to pH 5, 4°C virus/pH 7.5 virus	Binding to pH 5, 37°C virus/pH 7.5 virus
Y8	14.0	25.0
H2	3.4	5.4
H3	2.0	5.4
H18	3.2	6.0
H17	0.5	0.16

^aData from Fig. 9. 

^bThe epitopes of MAbs Y8, H2, H3, and H18 are exposed, and the epitope of H17 is reduced at low pH.