A method for synthesizing influenza virus-like particles (VLPs) within a plantor a portion of a plant is provided.The method involves expression of influenza HA of type A/California/04/09 inplants and the purification by size exclusionchromatography. The invention is also directed towards a VLP comprisinginfluenza HA protein of type A/California/04/09 and plantslipids. The invention is also directed to a nucleic acid encoding influenza HAof type A/California/04/09 as well as vectors. TheVLPs may be used to formulate influenza vaccines, or may be used to enrichexisting vaccines.
