These anti-H5 and F10-like Abs were further tested for their heterosubtypic HA binding and neutralization activity against Group 1 and 2 viruses. The acid-eluted anti-H5 Abs are not H5-subtype specific: they showed cross-binding activity to H1-NY18, to H3-A2/68, and weakly to H7-NL219 ( 