Fig. 2From: Process development for pandemic influenza VLP vaccine production using a baculovirus expression systemDiagram of the development of the upstream process. The upstream process combined a two-step strategy. The baculovirus was first amplified in Sf-21 cells to establish the virus stock, the baculovirus stock was subsequently used to infect High Fiveâ„¢ cells for the production of H7N9-TW VLPsBack to article page