Tissue binding specificity of FC and mFC:LS for human tracheal and alveolar sections.

A, Extensive staining of apical surface of human tracheal epithelia for the mFC: LS (green) against propidium iodide staining (in red) is observed. Bright staining of what appears to be goblet cells (inset at 20x magnification; indicated by white arrow) by this mutant HA resembles a similar pattern that was previously observed with 1918 H1N1 and 1958 H2N2 HAs. B, Shows minimal to no staining of apical surface of tracheal section by FC consistent with its low binding to human receptors on glycan array. C and D respectively show intense staining of alveolar section by mFC:LS and FC consistent with their high affinity binding to avian receptors.