Figure 4: Expression and characterization of VP60 insertion mutants harbouring influenza A virus M2e.

(a) The scheme shows names (left) and protein lengths in amino acids (right). The amino acid sequence depicted (M2e epitope) was inserted at the indicated positions in each VP60 insertion mutant. (b) SDS-10% PAGE analysis of H5 cell-lysates infected with recombinant baculoviruses expressing the indicated VP60 insertion mutants. (c,d) Western blots, performed using a rabbit hyperimmune serum against RHDV to detect VP60 protein (c), or a monoclonal antibody directed against M2e (d). (e) SDS-10% PAGE analysis of purified VLP preparations. Molecular weight markers (MW; ×103 Da) are given on the left. (f) Negatively stained purified particles corresponding to the indicated VP60 chimeric mutants analyzed by electron microscopy. Scale bar = 100 nm.