Comparison between HeLa-M2 and M2e-peptide immunosorbents. A. Binding of MAbs to HeLa-M2 (filled symbols) and M2e-peptide immunosorbent (open symbols), formed by coating wells with 50 μl of M2e-MAP at 0.2 μg/ml. Two MAbs that exemplify the opposite extremes in binding activity of currently available M2e-specific MAbs, are shown: 14C2-S1-4 (squares) and M2-1(triangles). Each symbol shows mean OD ± SEM of triplicates. B. M2-specific binding (Δ OD) against HeLa-M2 (closed symbols) and M2e-MAP (open symbols) of two representative sera (triangle, square) from groups of mice immunized by three inoculations with (4)M2e-MAP. C. As in B, except for using sera from mice that had been immunized by three consecutive pulmonary influenza virus infections. All assays were performed at least twice and a representative assay is shown.