Figure 6: Preparation of influenza multi-HA VLPs. (a) Baculovirus expression cassette and schematic composition of multi-HA VLPs [79]. The H5, H7, and H9 genes were derived from A/Viet Nam/1203/2004 (H5N1), A/New York/107/2003 (H7N2) and A/Hong Kong/ 33982/2009 (H9N2) viruses, respectively. Neuraminidase (NA) and matrix (M1) proteins were derived from A/Puerto Rico/8/1934 (H1N1) virus (shown in gray). (b) Transmission electron microscopy of purified multi-HA VLPs. The VLP preparation was negatively stained with 1% phosphotungstic acid and visualized on a Hitachi H-7600 transmission electron microscope. Size of VLP is indicated. Bar, 100nm.