Next, we wanted to identify amino acids in NA of H9N2 virus
that are critical for binding by the two mAbs. We selected antibody
escape mutants of X1 virus by co-culturing the virus and mAb in
embryonated chicken eggs.
Theescape mutants were further purified by limiting dilution in eggs.
One escape mutant, m1D1, was selected with antibody 1D1, while
two escape mutants, m1G8-1 and m1G8-2, were selected with
antibody 1G8. As expected, in ELLA and Mu-NANA assay, the escape
mutants were only poorly inhibited by the selecting mAbs