Maelenn CHEVREUIL has defended her PhD thesis entitled Self-assembly and disassembly dynamical phenomena in icosahedral viruses under the supervision of Stéphane BRESSANELLI and Guillaume TRESSET.
The self-assembly and disassembly of virus capsids, critical stages of the viral cycle, is a subject that arouses a lot of interest. However, the underlying mechanisms and, in particular, the kinetic pathways of assembly and disassembly, whether the capsid is empty or full, are not entirely solved. Time-resolved small-angle X-ray scattering is a technique for tracking processes involving nano-sized species with a time resolution of the millisecond order. Thus, in the case of the cowpea chlorotic mottle virus (CCMV), we have studied the self-assembly dynamics of capsid proteins with their genetic material. The experiments revealed the formation of amorphous complexes via a kinetic pathway called en masse whereas their relaxation into virions occurs via a so-called synchronous kinetic path. In the case of the hepatitis B virus (HBV), we were able to identify a probable disassembly kinetic path with the presence of an intermediate species organised like a fractal-branched structure. Finally, the assembly experiments revealed a kinetic pathway in three phases, i.e. agglomeration, growth and relaxation, directed by hydrophobic attraction and modulated by electrostatic repulsion.