Next, to assess the functional NAI antibodies, we constructed H6Nx reverse genetic viruses with mismatched H6 (to eliminate potential interference from HA antibodies in the human sera) and NA from seasonal A(H1N1)pdm09 (A/Wisconsin/588/2019), A(H3N2) (A/Darwin/6/2021), and A(H5N1) (N1 from HPAI 2.3.4.4b A/Texas/37/2024) viruses to assess the NAI antibody responses from seasonal influenza exposure by Enzyme-linked lectin assay (ELLA). This evidence concerns the gene XK and influenza.