Morphological characterization of a plant-made virus-like particle vaccine bearing influenza virus hemagglutinins by electron microscopy

Abstract

Plant-made virus-like particle (VLP) vaccines that display wild-type influenza hemagglutinin (HA) are rapidly advancing through clinical trials. Produced by transient transfection of Nicotiana benthamiana, these novel vaccines are unusually immunogenic, eliciting both humoral and cellular responses. Here, we directly visualized VLPs bearing either HA trimers derived from strains A/California/7/2009 or A/Indonesia/5/05 using cryo-electron microscopy and determined the 3D organization of the VLPs using cryo-electron tomography. More than 99.9% of the HA trimers in the vaccine preparations were found on discoid and ovoid-shaped particles. The discoid-shaped VLPs presented HA trimers on their ou..