The infectivity of H6N1 in CTE cells was further characterized at a MOI of 1. ICC results showed that the ciliated cells (Fig. 5D ), goblet and basal cells were all susceptible to infection by H6N1 as measured at 6 h.p.i. (Figs. 5E and 5F ). Although SAa2-3Gal expression was relatively low in goblet and basal cells, still 21.360.05% of goblet cells and 51.1610.9% of basal cells were infected. We speculated that the low infection of goblet cells by influenza virus at a high MOI might mediate through the binding to MAL-II specific SA or through a SA-independent pathway [18] . However, this hypothesis still requires the support from further experiments.