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Accueil du site > Animations Scientifiques > Séminaires 2007 > What determines the size of virus ?

What determines the size of virus ?

par Webmaster - 27 juin 2007

Orateur :

William Gelbart, The Virus Research Group, UCLA Department of Chemistry and Biochemistry, Los Angeles, USA

Salle : 118

Sujet :

The fact that the genomes of all viruses contain only a small number of genes (a few to a hundred), and that their protein capsids must be just large enough to protect them, implies a generic size of order 50 nm and — less obviously — icosahedral symmetry. Furthermore, the genomes of most bacterial viruses are double-stranded (ds) DNA, while those of most plant and animal viruses are single-stranded (ss) RNA. In this talk I discuss our lab’s theoretical and experimental work on three particular bacterial, plant, and animal viruses : lambda, cowpea chlorotic mottle virus, and Sindbis, respectively. I argue that the sizes of the genomes correlate with the sizes of their capsids according to the very different physical properties of dsDNA and ssRNA, specifically from the fact that the former is a stiff, linear, homopolymer while the latter is a flexible, heteropolymer with essentially undetermined secondary and tertiary structure. I describe various phenomenological theories used to predict and interpret capsid pressures in the case of dsDNA viruses, and measured radii of gyration and hydrodynamic radii from small-angle X-ray and fluorescence correlation spectroscopy experiments in the case of ssRNA viruses.

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