Understanding the self-assembly of simple icosahedral viruses
Guillaume Tresset (Université Paris-Sud)
Viruses are ubiquitous pathogens in all kingdoms of life and are major public health issues as well as economic and veterinary concerns worldwide. Despite a huge body of work dedicated to the molecular biology of viral life cycles, there are currently no physical models accounting reliably for the mechanisms by which the hundreds of molecular building blocks making up a virus fit into the final structure with a pinpoint accuracy. I will first present the self-assembly pathway of empty icosahedral capsids derived from a bovine virus. A kinetic model constructed from time-resolved X-ray scattering data reveals a cooperative mechanism involving an unexpected long-lived intermediate species. Then, I will give some insights into the packaging of polyelectrolytes by capsid proteins derived from a plant virus. Accurate measurements of the mass of packaged polyelectrolyte demonstrate a nonspecific selectivity that may play a crucial role for genome packaging in host cells. Quite generally, physics provides a useful framework to describe viral self-assembly and should eventually support the development of novel therapeutic strategies.