XK and influenza: DiLillo et al. (13) reported that the broadly binding human IgG1 anti-NA monoclonal antibody 3C05, with specificity shown for A(H1N1)pdm09 and the seasonal H1N1 virus A/Brisbane/07, relied on FcγR interaction for protection against influenza in mice, while an IgG1 antibody with specificity only for an A(H1N1)pdm09 strain, 3C02, did not.