Fig. 1.

Construction and expression of recombinant proteins. (A) Amino acid sequences of H5N1 and H7N9 M2e and FP of HA2 proteins. Amino acids with differences in M2e of H5N1 and H7N9 influenza viruses were shown in blue, and those in FP of H5N1 and H7N9 influenza viruses were in red. (B) Schematic structure of constructed M2e-FP-1 and M2e-FP-2 proteins. Linker sequences, GGGGS. (C) SDS-PAGE (left) and Western blot analysis (middle) of expressed M2e-FP-1 and M2e-FP-2 proteins. The protein molecular weight marker (kDa) is shown on the left. Anti-M2e antibodies (1:1000) were used for the Western blot detection. Shown on the right is the ELISA result for detection of the reactivity of M2e-FP-1 and M2e-FP-2 proteins with sera of mice immunized with M2e or FP peptides of H5N1 and H7N9 influenza viruses (1:2000). Sera of mice immunized with Middle East respiratory syndrome coronavirus (anti-MERS) were included as control.