Moreover, it is important to note that testing sera from virus-exposed and naturally pre-immunized vaccinated subjects in any ADCC assay with influenza-infected target cells would not be methodologically appropriate, since infected cells also express other ADCC-inducing antigens (like HA and NA), masking the NP- and M- specific ADCC activity we wanted to detect for FLU-v antibodies. This evidence concerns the gene XK and influenza.