Fig. 3. Heterogeneity in influenza virus particle morphology.

a | Traditionally, all pleomorphic influenza virus particles were thought to comprise viral components only. This traditional influenza virus particle is shown, displaying spherical morphology and consisting of haemagglutinin (HA), neuraminidase (NA), matrix (M1) and viral genomic material. b | Careful studies of virions have revealed a revised architecture consisting of an influenza virion that encases several components of host exosomes¹³¹. c | Influenza virus also assumes a filamentous morphology of variable length with polarized NA proteins. ANXA, annexin; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; UBB, ubiquitin.