As the flu pins you to your bed this winter, take a feverish minute to thank the biologists who help us understand the virus that causes it, the influenza virus. And maybe make a promise to yourself that next year you’ll spend 10 minutes to get the vaccine.
Influenza is an RNA virus that causes fever, chills, pain, fatigue, and general misery. After the virus replicates inside a host cell, it assembles at the cell’s plasma membrane. Virus particles then bud from the cell’s plasma membrane, taking some of the membrane with it, and search for the next cell to invade. A recent paper describes the membrane composition of recently produced influenza virus particles, and suggests lipid raft involvement in influenza virus assembly. Lipid rafts are specialized membrane domains that float freely in the plasma membrane, and have a distinct composition of proteins and lipids (specifically sphingolipids and cholesterol) compared to the rest of the plasma membrane. In this paper, Gerl and colleagues quantified the lipid compositions for the host cell’s total membrane, the host cell’s apical membrane (where virus particles bud from), and influenza particles budded from these cells. The virus particles contained more sphingolipids and cholesterol than the host cell’s total or apical membrane, consistent with a model of virus budding from lipid rafts on the apical membrane. The electron micrographs above show purified spherical influenza virus particles recently budded from host cells.
Gerl, M., Sampaio, J., Urban, S., Kalvodova, L., Verbavatz, J., Binnington, B., Lindemann, D., Lingwood, C., Shevchenko, A., Schroeder, C., & Simons, K. (2012). Quantitative analysis of the lipidomes of the influenza virus envelope and MDCK cell apical membrane originally published in the Journal of Cell Biology, 196 (2), 213-221 DOI: 10.1083/jcb.201108175