Figure 3. Concomitant presence of H1 and H3 glycoproteins on the surface of influenza VLPs. The graph shows the presence of both H1 and H3 glycoprotein types after performing a qualitative sandwich capture ELISA using specific H1 and H3 mAb. Similar to the titers obtained by HA assay, the highest OD was found for fractions 5 and 6 as indicated in arrows.