Fig. 6.

Position of HA and NA mutations acquired by panel of A/H3N2 viruses upon HAE cell passage. Top left: frequency of mutations acquired in HA globular head that may affect receptor binding and/or antigenicity. Percentage values are the average of three RT-PCR reactions from viral RNA samples. Top right: mutations mapped onto globular head of H3 structure (protein databank reference: 3ztj). The red dotted circle shows the location of the receptor-binding site. L194syn indicates a synonymous mutation. Bottom left: mutations in residues in and around the NA enzymatic pocket. Bottom right: mutations mapped onto the surface of human N2 globular head (protein databank reference: 4gzt). A close-up of an enzymatic pocket with sialic acid residue within is in gold.