Fig. 4. Epitopes that are broadly conserved in influenza B virus glycoproteins are largely absent the WSEIV HA and NA, with cross-reactivity being mostly restricted to the stalk domain of the HA and active site of the NA.

A and B Binding profiles of broadly cross-reactive anti-influenza B virus HA and NA human (H) and mouse (M) monoclonal antibodies in ELISAs are shown against recombinant B/Malaysia/2506/2004 and WSEIV HA and NAs. 4F11 (anti-influenza B virus NA) and 4C2 (anti-influenza B virus HA) mouse mAbs were used as negative controls for the ELISAs against the HAs and NAs respectively. C Presence of pre-existing immunity or induction of cross-reactive antibodies against the WSEIV HA and NA was evaluated through ELISAs using human serum samples obtained post-seasonal influenza vaccination (n = 18). Mopeia virus glycoprotein was used as a negative control for baseline establishment, and area under the curve was calculated with a cutoff of average plus three times the standard deviation of the blank wells. The geometric mean for each group is indicated with a line. Experiments were performed once in technical duplicates.