Fig. 1

Immunogen constructs. A Mimic positions of the H₃, H₄ and H₅ sequences on the haemagglutinin protein. B Construction of a prokaryotic expression system of antigenic epitopes. The ferritin sequence was ligated to the C-terminus of the epitope sequence by a linker. A His tag was added to the C-terminus of ferritin and inserted into pet20b ( +) between the NcoI and XhoI sites. C Schematic illustration of psecTag2A. Ferritin was connected to haemagglutinin in the same way, and a His tag was added to its C-terminus in psecTag2A between the EcoRI and XhoI sites