Figure 1

Architecture of the influenza virion. While the virus has often been depicted as spherical in microbiology textbooks [14], recent investigations suggest a far more pleiomorph appearance, only some particles being essentially spherical while others are tubular. The approximate length of the virion is 120 nm, possibly influenced by the organization of the RNA by the multiple ribonucleoprotein complexes [19] shown in the center of virion surrounded by the capsid and layer of matrix protein M₁. The relative abundance of the HA and NA proteins are indicated based on reports by Mitnaul et al.[20] and Zhang et al.[21] (components not to scale). Based on data from the report by Gjelstrup et al.[22], a 6×MBL₃ oligomer is drawn to scale relative to the size of the influenza virion.