We next determined the influenza virus type recognized by individual HuMAbs. First, an immunofluorescence analysis was carried out and the results were as follows: E-1 recognized H1N1; A-2, B-1, B-2 and D-1 recognized H3N2; and A-1, B-3, C-1, D-2 and E-2 recognized B viruses. Representative results of B-1 and D-1 to influenza A virus (H3N2) and B-3 and E-2 to influenza B virus are shown in Fig. 1A. As control antibodies, we used several anti-influenza HA and NP murine MAbs. The staining pattern of infected MDCK
PF-562271 obtained with our HuMAbs was very similar to that obtained with the anti-HA, but not anti-NP murine MAbs. PAP staining and ELISA of these HuMAbs gave the same results (Table 1). Five MAbs (E-1 to H1N1; B-1 and D-1 to H3N2; and A-1 and C-1 to B) showed distinct bands of HA protein on Western blotting, but the other MAbs showed little or no reactivity with any viral
proteins including HA by this method, indicating their recognition of conformational epitope(s) (Fig. 1B). As a control antibody, we used 2000-fold dilution of donor B-derived plasma.
