Understanding hepatitis B viral capsid diffusion, dissociation and toxicity in live hepatocytes

Hepatitis B virus (HBV) is an enveloped DNA virus that infects human liver cells. HBV has infected more than 250 million people globally, despite the availability of a vaccine. Once HBV enters the cell, its life cycle involves disassembly of the capsid into individual capsid proteins, to release the genome into the host nucleus for repair and protein expression, followed by capsid-envelope protein interactions that lead either to nuclear import and possibly disassembly at the nuclear envelope, or secretion from the host cell. However, a quantitative model of all the steps involved is still lacking. Here we quantify HBV capsid diffusion, disassembly into core (capsid) protein, and capsid-envelope interactions in live hepatocytes, using Fast Relaxation Imaging (FReI), Widefield Intensified Fluctuation Imaging (WIFI), and single molecule tracking by Minflux to obtain a sub-cellular and as well as molecular-level understanding. Our observations show signs of liver-cell specific adaptations of HBV. We look at multiple cell lines of liver and non-liver origins to further explore this specificity, which may provide implications on the co-evolution and host-cell specificity of HBV even beyond the point of cell entry.