Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 14: Membranes and Vesicles
BP 14.3: Vortrag
Mittwoch, 28. März 2012, 10:15–10:30, H 1028
Insights into the mechanics and uncoating of influenza virus from atomic force microscopy studies — •Frederic Eghiaian1, Sai Li1, Christian Sieben2, Claudia Veigel3, Andreas Herrmann2, and Iwan Schaap1 — 1D.P.I, Georg-August-Universität Göttingen — 2Institut für Biologie, Humboldt Universität, Berlin — 3Lehrstuhl Zelluläre Physiologie and Centre for Nanosciences, Ludwig-Maximilians-Universität München
During the assembly and budding of the influenza virus, the viral genome is recruited in virions by the matrix proteins. This matrix forms a pseudo-continuous shell that coats the inner layer of the cellular membrane, following which capsule shaped viruses bud out of the cell. After infection this morphology, as well as the membrane-matrix-genome interaction is lost when the virus reaches the acidic endosomes, an essential step for fusion and the release of the viral genome. Using AFM we investigated the contribution of the different building blocks and the effect of pH on the mechanical properties of the virus. Contrary to protein-based capsids, Influenza virions proved highly flexible yet relatively hard to break open, a property that results from the selection of a lipid bilayer as a protective envelope. At the acidic pH of late-endosomes, the stiffness of the viruses decreased irreversibly to a value comparable to that of its lipid envelope alone. Interestingly, at the pH of early endosomes, the virus partially softened, which enhanced its fusion activity. Completed by fusion assays, our AFM study explains how low pH dismantles the flu virions, which has implications for both the viral budding and fusion mechanisms.