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. Author manuscript; available in PMC: 2016 Sep 1.
Published in final edited form as: Arch Biochem Biophys. 2015 May 6;581:86–97. doi: 10.1016/j.abb.2015.04.011

Figure 2. Structure of influenza virions by cryo-EM and cryo-ET.

Figure 2

A–D, Influenza virions imaged in conventional cryo-EM projections (A & B) or in phase-plate-enhanced cryo-EM projections (C & D). These virions either contain an M1 matrix layer underneath the viral envelope (A & C) or lack it (B & D). The X-31 (H3N2) strain was used for A & B and the A/NewCaledonia/20/99 (H1N1) strain was used for C & D. E, cryo-ET section of virions at neutral pH (X-31 strain). The insets at bottom right show virions containing solenoids. A & B are reprinted from Fontana and Steven, 2013, At Low pH, Influenza Virus Matrix Protein M1 Undergoes a Conformational Change Prior to Dissociating from the Membrane, Journal of Virology 87(10):5621-8, with permission from the American Society for Microbiology [13]; C & D are reprinted from Yamaguchi et al., 1998, Zernike phase contrast electron microscopy of ice-embedded influenza A virus, Journal of Structural Biology 162(2):271-6, with permission from Elsevier [12]; E is reprinted from Harris et al., 2006, Influenza virus pleiomorphy characterized by cryoelectron tomography, PNAS 103(50):19123-7, with permission from the National Academy of Sciences of the USA [27]. Bars, 50 nm in A–D and inset of E; 100 nm in E.