Tracking lipid surface area in the human influenza A virus
Abstract
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The human influenza A
virus causes three to five million cases of severe illness and about 250 000 to
500 000 deaths each year. The 1918 Spanish Flu may have killed more than 40
million people. Yet, the underlying cause of the seasonality of the human
influenza virus, its preferential transmission in winter in temperate climates,
remains controversial. One of the major forms of the human influenza virus is a
sphere made up of lipids selectively derived from the host cell along with
specialized viral proteins. I have employed molecular dynamics simulations to
study the biophysical properties of a single transmissible unit--an approximately
spherical influenza A virion in water (i.e., to mimic the water droplets
present in normal transmission of the virus). The surface area per lipid can't
be calculated as a ratio of the surface area of the sphere to the number of
lipids present as there are many different species of lipid for which different
surface area values should be calculated. The 'mosaic' of lipid surface areas
may be regarded quantitatively as a Voronoi diagram, but construction of a true
spherical Voronoi tessellation is more challenging than the well-established
methods for planar Voronoi diagrams. I describe my attempt to implement an
approach to the spherical Voronoi problem (based on: Hyeon-Suk Na, Chung-Nim
Lee, Otfried Cheong. Computational Geometry 23 (2002) 183–194) and the
challenges that remain in the implementation of this algorithm.