PhD defense of Kalouna KRA

Kalouna KRA has defended her PhD thesis entitled Structural study at high spatio-temporal resolution of the effects of hepatitis B virus capsid assembly modulators under the supervision of Stéphane BRESSANELLI and Guillaume TRESSET on December 11, 2023.

Hepatitis B virus (HBV) is one of the most serious human pathogens, and currently available treatments can only control infection, not cure it. Assembly modulators are candidates for the development of new anti-HBV drugs. They are a new class of molecules that disrupt capsid assembly. These molecules are also powerful inhibitors of HBV replication in vitro. The mechanisms of action of these modulators have been elucidated by in tubo studies on the capsid protein Core. However, the action of modulators on the assembly pathways and non-equilibrium intermediates that condition capsid formation remains unknown. In this thesis, an innovative approach combining physics of biological objects and structural virology was used to study, at high spatial and temporal resolution, the influence of different modulators on the assembly of capsids formed from three recombinant Core proteins.
This work combines time-resolved small-angle X-ray scattering on synchrotron sources and cryo-electron microscopy. Thanks to these techniques, we were able to show that modulators accelerate the assembly kinetics of hepatitis B virus capsids and lead to a modification of the structure of the objects formed as a function of the type of modulator and its concentration during assembly. We have also analyzed the effects of a new type of modulator which would lead to the formation of a lower number of capsids. Finally, we show that pregenomic RNA also influences capsid assembly speed.